There has been much talk of alternative fuels to keep our classics going as petrol becomes ever less attractive. But after all is said and done, more has been said than done.
Here is a brief summary of my experience and some hearsay from down the pub, it is quite possible I have made a mistake here or there so if you spot one do let me know.
Mostly Propane with a splash of Butane, stored as a liquid under a pressure of about 5 bar in steel cylinders. The fuel is turned into a gas and the pressure regulated in an evaporator that is heated by engine coolant. The simplest way of feeding the gas into the engine is by using a gas carburettor, but these are quite restrictive and so peak power is significantly reduced, maybe by 20%, although most drivers don’t notice this for some reason. Often these systems are set up to run very rich to mask installation problems. Better way is to use gas injectors, similar to petrol injectors, with their own ecu, this is more expensive but more efficient.
LPG is usually less than half the price of petrol per litre, and although the fuel consumption on gas is slightly worse there is still an overall saving. A well set up system will have lower HC and CO emissions than petrol, but the higher fuel consumption leads to similar CO2 levels.
LPG has a higher octane rating and so engines can be redesigned with higher compression ratio to achieve higher power and economy, but again that is expensive.
As LPG is a dry fuel there can be issues with valve seats wearing, but only if the engine is worked hard. Special lubrication systems are available but many have problems with uneven distribution between the cylinders.
LPG supply is directly related to oil supply, so if petrol runs out then so does LPG.
Methane / CNG.
This is the same gas as you get in your domestic cooker, Compressed Natural Gas. On cars it is stored in very high pressure cylinders. You can get domestic pumps to fill the car from a household supply. The regulator and engine conversion equipment s similar to LPG, but with different flow rates. Again there is a power loss, slightly greater than LPG but not horrific.
Also the valve wear issues are similar to LPG.
An alcohol fuel with a fairly low energy content, so less power than petrol in a standard engine, but the high octane rating means that add a turbo or supercharger and you can have a very powerful unit. But if you’re happy with the power loss on a standard engine then home brewed methanol could be a cheap alternative to petrol. Unfortunately it’s very hydroscopic so cant be stored for long periods.
An alcohol fuel with a fairly high energy content and octane rating, it makes a small gain in power on standard engines but can make even better gains on a modified engine with higher compression ratio or a blower.
It is very hydroscopic so has a limited tank life, it also has an unfortunate tendency to react with steel creating an acid that corrodes pretty much everything. So stainless or plastic fuel pipes, tanks and fittings are helpful. The exhaust is also corrosive so stainless systems are best.
Alcohol fuels can be brewed in much the same way as moonshine, using food waste, but getting the water out is very difficult.
Flow rate is much higher than petrol, so the fuelling system has to be modified to suit, although some conversions have managed to use standard injectors and fuel pumps.
It has no carbon and the only emission is water. Unfortunately its very difficult to store, requiring cryogenic tanks. As it is the smallest atom it tends to leak through pretty much anything, including steel. It also needs either very high pressure tanks or cryogenic (-253.7 ºC) liquid storage. The other problem is that its energy density is quite poor, so you need a lot of it. If it is injected into the port it displaces quite a lot of air, so power is significantly reduced. But of course this could be tackled by using a bigger engine or turbos, yes its true, with hydrogen you can have a guilt free 8 litre V8! British company ITM Power have developed a home hydrogen generator, simply add water and plug it into the mains, to prove its usefulness they converted a Focus which gets about 100 miles per fill.
And Sunderland university have used CNG (compressed natural gas, mostly methane) equipment, which is similar to an LPG conversion, with a special tank to run a standard car on Hydrogen. Again it’s a dry fuel so valve seat erosion can be a problem if worked hard.
Another brewed fuel, usually made from oily seeds or waste cooking oil. Quite expensive to produce on anything other than large scale industrial quantities. ‘Phase 2’ biodiesel is made from farm waste (husks and stalks left over from food production) and is more expensive but does not use up the worlds food supply.
Performs just the same as regular diesel as long as it is filtered properly. Because of the greater solvent content it will loosen any old fuel deposits from an old cars fuel system, which can clog filters and injectors, so its best to fit a new fuel filter then run biodiesel briefly before changing the filter again.
Being an organic substance it is prone to stuff growing in it, so it has a limited tank life.
Some people run older diesels on filtered chip oil, there are lots of microscopic plant particles in this which carbon up the injector tip and can coke up the engine. The harder the engine works the worse the problem gets. Using modern diesel can wash some of the deposits away, so alternating fuels can extend service life. Modern diesels use much finer tolerances in the injection system and are a lot less tolerant of this type of fuel, but old fashioned mechanical diesel injection systems don’t seem to mind so much.
Throw the engine away and fit a milk float motor? It has been done, in fact I did it to a Fiat X1/9 but that’s another story, but you have the performance of a milk float and the batteries are very heavy and take up a lot of space.
However, recently the century of pitiful investment has come to an end and the technology is finally getting proper funding. We now have electric sports cars, and even a few supercars. So over the next few years expect to see much more viable electric drive systems and batteries.
Personally I would love to develop a replacement electric system in the shape of an engine, I think that would be rather fun.
Advanced fuels from petrol stations.
Things like BP Ultimate and Shell V Power are formulated to coat the cylinder in a low friction coating, improve oil control and disperse more effectively to improve flame efficiency.
This does actually work, an engine improves over time with use as the coating builds.
The fuels cost more which can negate the economy benefit, depending on the engine and how much difference the fuel makes on that particular design.
Hydrogen in petrol.
Mixing about 3% by volume hydrogen in the intake air can allow a petrol engine to run very lean, in this condition it is possible to gain 25% in efficiency. Maximum power will be reduced due to the displaced air, and the hydrogen requirement is quite large so generating it by an on-board electrolysis system is not usually viable. Also the engine change to make use of the lean burn potential is significantly expensive.
Introducing hydrogen without running the engine lean makes no improvement.
Using a jam jar of water and 12v electrodes is just plain silly.
A variation on this theme is to use thermal and catalytic cracking on the petrol to turn it into hydrogen and CO2, with engine modifications this can improve efficiency by up to 30% at part load. But its a very expensive system and complicated to control.
LPG in diesel.
Can improve efficiency by up to 20% but makes an even more dramatic improvement to performance. Over doing it will melt the engine, much like nitrous oxide on a petrol engine.
Cheaper than a conventional LPG conversion, this works very well indeed if set up properly.
The following things really don’t work.
Magnets, they have no effect on fuel what so ever.
Solid fuel ‘catalysts’, I have tested a few and none made any difference.
Air flow vortex or turbulators, these usually have absolutely no effect, although they do block the intake and turbulent air reduces flow rates, so they can actually reduce performance. Cars with mass air flow meters require extremely non turbulent flow, and usually have flow straighteners built in, turbulent flow creates false readings and may make the engine run slightly rich
Porsche is a very powerful word. As brand names go it’s a bit like Marmite. But love it or hate it one thing is certain, their cars are fast, designed for performance and driver enjoyment. Of course, to get the best out of such a specialised machine the driver needs to have the right skills and experience too, but crucially these driver skills are of huge benefit to any driver no matter what car we drive.
In fact you don’t even need to be a Porsche fan to benefit hugely from a bit of driver training, such as the rather brilliant packages on offer at the Porsche Experience Centre. Situated in its own dedicated complex of test tracks just a few yards from one of the fastest corners at Silverstone race circuit, it has a bit of everything to allow drivers of all levels to safely learn and develop their skills.
The main circuit is not really a race track, its flowing twisting curves are actually designed to replicate the most demanding country roads. Here you can learn how to approach corners safely whilst enjoying the full potential of one of the centre’s immaculate Porsche cars. Their skilled instructors, most of whom are professional race drivers, first asses your ability at modest speed, then identify areas where you can improve and then gradually build your skill and confidence at a pace that suits you.
You don’t have to drive fast either, they go at your pace making sure you are comfortable with the speeds. They can teach you road craft, how to balance the car and how to control it in emergencies, so when something springs out in front of you on the road home you should be better able to react and maintain control.
One crucial part of coping with emergencies is skid control, and although modern Porsches have stunning dynamic stability control systems built in it is still essential that the driver knows what to do should the unexpected occur.
To this end the Centre has two dedicated skid control areas where you can practice not going sideways, these smooth plastic roads are irrigated with soapy water so it can simulate the worst black ice. One area is on a hill which is set up as a series of corners, demonstrating superbly how quickly things can get out of hand if you don’t react at the first sign of a skid. The first time I tried it I drifted reasonably elegantly through the first corner, but the turn into the second put the car into a massive skid and the final corner was taken very inelegantly backwards! But with the skilled guidance of my coach the next pass was taken largely in the intended direction, if a little ragged. By the third pass all was well, under control and I was able to keep the car on the correct side of the road. I’m sure you’ll agree these skills are vital in any car, not just a high powered sports car.
But of course it’s one thing to enter a skid pan fully aware of what lies ahead, in the read world you may get no warning. The Porsche Experience Centre have this covered too, they have another skid pan with the same super slippery surface, but this time it’s flat and very wide with a very sneaky surprise at the start. You are asked to drive at about 15mph in a dead straight line, a simple instruction to get from one end of the surface to the other, it should be simple. But as soon as you enter the plastic road section a computer controlled kick plate throws the back of the car sideways with a violent jolt, the system can be set up to be mild or seveqre, usually it is set to be random so that you have no idea how sideways the car will go, or indeed in which direction! This is a fantastic facility, no other track I know of has the ability to continually surprise on every lap. After just a few passes I found my reactions improving, becoming more instinctive and flowing.
This area also allows the staff to demonstrate exactly what all those stability control systems actually do, taking runs over the slippery stuff first in normal fully assisted mode, here you have to steer into the skid but the car then brings everything into line very swiftly for you. Then there is a run with stability control off but traction control still on, here you have to put in much more steering input to keep things going in the right direction and then counter steer to avoid the car flicking back the other way. Finally they let you do a run with it all turned off, with only your wits to help you as the inevitable series of dramatic spins awaits. This remarkable demonstration really does show just how brilliant modern car technology is and is well worth doing.
I was fortunate enough to spend a day there courtesy of Porsche GB PR, but a variety of courses are available for anyone who fancies learning something new, you don’t need to be a Porsche driver or even have a fast car, they have a selection of cars for you to use including their luxurious executive saloon and the Cayenne off roader. And it’s not all about speed, there are road based courses, off road courses and you can even book a session in their classic ’70s 911. There is something to cover every aspect of driving, and before you ask yes I am going to book one myself!
On most cars built in the last 14 years there is a little yellow warning light with a picture of an engine on. This ‘Check Engine light, sometimes called the MIL light (Malfunction Indicator Light), comes on when something is gone wrong with the engine, it might not be a big problem but the engine’s computer thinks it’s at least bad enough for the car to fail an emissions test.
The great thing about these cars is that you and I can read its mind.
It’s been a long time since On Board Diagnostics (OBD) became standard on cars. There have been a few variations on the theme, such as K line or CAN, but these days there are a respectable number of fairly cheap devices that can read fault codes, making looking after your car that bit easier. In fact I would encourage any car enthusiast to get one.
For instance I use an application for my Android phone, it’s called Torque (I reviewed it in Evo magazine last year) and it cost me the princely sum of £2.92. To be able to physically talk to the car I connect it using a Bluetooth OBD interface based on the ELM327 chip, which cost about £12 off eBay. This allows me to read fault codes from the engine, and when appropriate to clear them. It also allows me to look at the values from sensors such as coolant temperature, engine speed and the signals from the oxygen sensors.
This is very handy when you like playing with bargain bangers, which tend to be about ten years old and frequently come pre-equipped with a host of minor faults. In fact I used it on the last car I bought, I must confess that I did something that I always advise other people not to do and bid on a car on eBay without viewing it! So when I went to pick it up I plugged my phone in to the OBD port and listed off the current faults, then had a chat with the seller about their claim that the car was ‘faultless’. We came to an arrangement.
They say knowledge is power, and knowledge of what’s on a cars mind certainly does give you bargaining power.
And all power came for less than £15, not bad.
I use this kit for servicing and maintenance, it can indicate when a small exhaust leak has just started or when an air meter is dirty and is reducing performance and economy. But I also use it for tuning, I’ve tried different spark plugs and checked the knock reading as well as watching the fuel flow to see if the efficiency has improved. As the phone has GPS I can compare the actual road speed to the speed the car thinks it’s doing, handy for calibrating the speedo when fitting bigger tyres. For someone who like to play with their cars this info is very useful, years ago kit to measure these things would have cost thousands, but now it’s cheaper than a large box of chocolates.
In fact I even use it when I’m working on prototype and experimental cars, as a first line in fault finding and making sure a car is running correctly before an important test.
I also have kit that does indeed cost many thousands, but it is bulky and needs a laptop (for those in the know I’m talking about INCA and an ES592 with all the leads and faf) so if I just need to have a quick look at the basics then I’ll use my phone instead.
Amazingly the app is so good that it can record data from the phone’s other features at the same time, so I can do a few laps of a test circuit and record critical values such as temperatures, air flow, fuel flow, lambda end engine speed, whist at the same time recording G forces from the Android phone’s inbuilt sensor and also record video from its camera. This gives me a very useful log file showing exactly what went on in the engine as I throw the car through the twisty bits.
Of course it doesn’t do everything that full professional kit does, but it gets pretty damn close for a fraction of the price. I am still impressed one year on.
But even for the normal car enthusiast this kit is really useful, even if you only use it for fault code reading and resetting the ‘Check Engine’ light. I have seen many dealers charging around £250 for this service, so if you only ever use it once you’ve saved a packet.
I should mention at this point that there are two completely separate sets of fault codes from the engine, the set used here is the standard set that is dictated by law, all cars use this set and it includes the ability to clear codes and reset the fault light. But there is also a second set that is manufacturer specific, this allows for unique design features and gives more detail, a simple reader won’t usually understand these codes. Some companies such as VAG make heavy use of these special codes, but even so a basic reader will still tell you if something is not right.
However I have to sound a warning, these fault codes are not to be taken too literally. A common problem is a slightly corroded connector leading to an incorrect diagnosis of a failed sensor, imagine a little bit of moisture creeping into the engine speed sensor connector, leave it a few years and a tiny spot of corrosion forms. Some days when you go to start the engine it doesn’t get a signal from the sensor and so flags up a sensor fault. You take the car to a dealer who plugs in the diagnostic tool, see the fault code and immediately replaces the perfectly good sensor with a new one. When they plug the new sensor in the tiny spot of corrosion is scraped off and all seems fine again. Two things happen, firstly you get charged for a sensor you didn’t need, and secondly about a year later the same fault re-appears. All it needed was the connector cleaning and a quick squirt of contact grease.
Another classic fault is an oxygen sensor reading too lean, but rather than the sensor being at fault it is more likely to be a small exhaust leak that’s causing the problem.
So you see, fault codes can be misleading. They are great for telling you the area that has a problem, but this is only the start of the investigation for a competent mechanic.
It’s one thing to read fault codes, it’s another to actually understand them.
But don’t worry if you are not a trained engineer, owning a code reader is still great because you can read the codes and go onto your car’s model forum and ask the collective expertise what might be causing it. The internet is great for this kind of wisdom, and one thing car enthusiasts are good at is talking about problems and solutions. We are no longer limited to just the contents of our own brain.
There are limitations to the ability of cheap devices, most wont read codes from your ABS system or be able to program new keys to your car, but for the rare times you might need one of these features there is usually someone from the forum or club near you who has the kit and is only too pleased to help.
Your car diagnostics should not be a mystery to you, codes were standardized by law to make sure we all had the ability to fix and maintain our cars, so go on, splash the cash on a new gadget and explore your motors mind.
And yes, I am full expecting to get bombarded with questions about codes on my Twitter account now! 😉
I have had a lot of questions about setting up old Jags for race and track day action, so here are a few answers for those that feel the need to experience the glory of a V12 on track.
The same basic principals apply to both XJ-S and XJ6/12 cars. First up which car to go for.
The V12 in 5.3 form is fantastic on the race track with a 6500rpm rev limit and over 300bhp readily available, although the standard cooling system is dire. The first V12s had flat cylinder heads and can be tuned up to over 600bhp (at great expense), later models had the High Efficiency HE heads which limit power but drastically improve fuel ‘economy’ and is still good for well over 400bhp. Early cars had a 4 speed manual gearbox as an option but these are hideously expensive, most have the immensely tough GM TH400 auto box which can also make a good race box when fitted with American drag racing parts. I raced an auto with manual override and it was superb. The last XJS cars had the 6 litre V12 with a 4 speed 4L80E auto which can be modified to work in manual mode either mechanically or electrically (paddle shift style), but these cars are rather expensive.
The 6 cylinder engines in the XJ-S were either the AJ6 in 3.6 or 4.0 forms or the four valve AJ16 version of the 4.0. All are powerful with over 300 bhp quite feasible. Available with either the 5 speed manual or the 4 speed ZF auto, again the auto can be modified for racing but the manual is a simpler option.
TWR offered a manual version available through the official Jaguar dealer network, this used the Getrag 260 gearbox as found on larger BMWs of that era, but as the gearbox has an integral bellhousing you will need an adaptor plate to fit a non-v12 sourced box.
Basic track mods:
Brake pads, race brake fluid, jack the bonnet open an inch and fit good tyres. Give it a full service and off you go!
The more complicated version:
All cheap cars are rotten, so plan for welding. The front subframe which holds the engine up and holds the suspension on rusts from the middle out, good second hand ones are over £250 and quite a big job to change, so make sure you get a good one. The smaller cross member under the radiator also rots out but can easily be replaced with a strip of suitable metal and is not a deal breaker.
The front of the sills rots behind the ally splash guard but is reasonably simple to repair. The back of the sills is a very complex construction and includes the rear axle radius arm mount, this is a sod to rebuild but for racing it can be simpler to just cut the whole lot out and weld in a simple sill and convert the radius arms to a ‘cotton reel’ bushed rod that is mounted into a fabricated box intruding into the rear passenger foot well. This mod cuts out some weight too and also improves axle location.
When viewing a car pull up the rear seat base, rain water leaks in from the quarter light seals and pool in the seat base/ inner sill area. The race car solution to a rusty bottom is to cut out the set base and weld a simple plate over it. Also check the front foot wells where water from leaking screen seals can pool and rot the floor. Many cars have been undersealed which is unhelpful as the rot starts from the inside of the car and the underseal can hide it from inspection.
Mechanically the cars are strong, but bushes, bearings and ball joints wear. For racing I replace bushes with polyurethane and budget for new bearings and ball joints. Brakes get extremely hot so we use BNS grease in the wheel bearings which copes with the heat. The gearbox mounting is a cunning and complex unit which will be worn and make clonking noises when driving hard but can be replaced with a simpler rubber mount. The steering rack has very soft bushing so fitting pollybushes sharpens up the steering considerably, some cheapskate racers just limit movement on the bushes by simply putting tie wraps round the bush edges!
The cooling system on V12s is dire, I flushed the accumulate rubbish out then fitted coolant made of about 1% water wetter, 10% anti-freeze and 89% water which has better heat transfer ability. Then I removed the visco fan and associated heavy bracketry, the fan cowling and the original electric fan. I fitted a large electric fan instead as the fan is only needed in the pits. Jacking the bonnet open an inch lets the hot air out which is just as important as letting cold air in.
The brakes fade horribly on track, I used EBC Yellow Stuff race pads and Motul RBF600 brake fluid. The fluid is vital, it has a higher boiling point but has to be changed more regularly. To get a bit more cooling air round the rear inboard brakes I took the access plates out of the boot and removed the boot seal to let the hot air out, another approach is to cur the boot floor out completely which further improves cooling and makes access much easier to the rear axle as well as saving weight.
Weight loss is key, the sound deadening is everywhere and it is a good days work ripping it out. A tar based substance is glued onto the floor and has to be chiselled off. The interior heater system is very heavy and can be largely thrown away, although leaving the drivers side screen fan helps demisting. I used RainX anti-fog on all the glass to prevent misting, much lighter solution than a heater. The standard XJ-S seats only weigh 7kg so make a good cheapskate racers choice. Door lock solenoids can be junked to save 2kg, but the door cards weigh naff all so leave them in. I would also leave the electric mirrors on as they are less than 1kg each and work very well.
The centre exhaust silencer can be replaced with a straight through tube for a few more bhp and less weight. The standard intake airbox is a little restrictive and the trumpet can be cut off and a larger hole formed with a radiused edge, it is vital to get cold air to this and running ducting from the headlight surround works well. The middle headlights on quad light models can be removed to make an excellent cold air intake point, although some bodywork has to be cut out to get into the engine bay. The standard paper air filters work well when new, no need for expensive sponge filters.
The engine oil needs to be able to cope with high speeds and temperatures, I used Castrol RS which is now superseded by Castrol Edge. The other fluids have to be changed for quality higher performance versions too, including power steering, gearbox and differential.
All XJ-Ss had and LSD as standard, the 6 pot models had the lower 3.54:1 ratio needed for racing and is a straight swap to replace the overly high V12 item.
With the car lighter it will sit stupidly heigh on its springs. Eibarch make a suitable race springs but they are pricey. I cheated slightly by using the Jaguar ‘Sports Pack’ springs from a 3.6 model on my V12 which worked out just right. Adjustable front dampers are a handy mod and can be tweaked to suit different circuits – hard for flat ones like Silverstone and softer for less even ones such as Croft.
Fitting 50 profile tyres on standard wheels drops the gearing a tad more and lowers the car a bit too. Buffing the tread down to 4mm will stop them going off due to heat build up, this maintains grip levels and actually improves wear rate. I used Toyo Proxes T1R tyres as they were mandated by the race series, and they seemed to work well even in heavy summer rain.
You may wonder about roll cages, but if the car is ever used on the road I would avoid them because of the injury risk from hitting a steel bar next to your head in a collision. Cages work well when the driver is secured in a race seat with a race harness and wearing a crash helmet. The Jags are strong cars anyway so a heavy cage is of questionable benefit unless racing.
All that remains is to fit a race harness to hold you steady and a race steering wheel to speed up response and it’s time to head for the track to have more fun than is decent.
Check out these web sites which I have found very useful:
If you don’t have winter tyres this winter you may be wondering what all the fuss is about, and hopefully when you open the curtains in the morning to find a few inches of snow you will very sensibly leave the car at home.
Ordinary tyres are a mixture of many different substances including rubber, carbon black, silicon, sulphur and the steel or kevlar reinforcing wire. The best tyres may actually have over a hundred different substances in, and the exact blend and cooking method can produce a range of tyres with very different abilities.
Ordinary tyres, sometimes referred to as summer tyres, are engineered to work well when hot, to last a long time and provide good dry grip. The rubber based tread compound in summer tyres is relatively hard and the tread blocks are relatively shallow and broad so they remain stable when pushed hard round corners etc.
By comparison a winter tyres is made of a much softer compound which grips the road even when cold. If you run your hand over the tread of a tyre on a cold day a winter tyre will still feel rubbery but a summer tyre will feel harder, more like wood.
But also the tread pattern is very different, the winter tyre will have deeper and narrower tread block, each with a multitude of deep cuts moulded in. This allows the tread to move about very easily and mould itself to the irregularities of the road, allowing it to grip even on ice.
But there is more to tread wobbliness than that, rubber tread grips my moulding itself in to the road surface at a microscopic level, almost flowing over the tiny irregularities of the road surface and grabbing hold of them. But it takes time for the rubber to move into position, only a tiny fraction of a second, but whilst it is taking hold it needs to be almost stationary. Any slipping will prevent it taking hold properly and you get drastically reduced grip, that’s why wheel spin needs to be avoided.
The tread allows this to happen by moving very slightly with respect to the tyre body (carcass), allowing the rubber in contact with the road to remain stationary as the wheel moves above it.
In fact if you look at a graph of wheel slip against the amount of drive force actually being transmitted to the road you see a peak at about 3% on a summer tyre as the force makes the wheel turn slightly faster than the road beneath it whilst the tread is constantly moving back and forth as it passes through the contact patch. But as more throttle is applied and the slip increases it suddenly gets to a point where the tread movement can’t keep up, it starts sliding across the road and never has time to flow into the road surface, and then grip drops rapidly.
There’s a lot going on in that tyre of yours.
So the softer tread compound coupled with the wobblier tread block pattern gives a winter tyre much more time to get a really good grip of the road.
Of course there is a down side to this, the wobblier tread means the car can drift more when pushed hard as the tread blocks almost ‘walk’ across the road surface, you’re not actually skidding but you’re not going exactly where the steering is pointing either. This also means that a winter tyre used in the summer will give worse stopping distances too, in fact a winter tyre starts to let the side down when temperatures go above 10°C and stopping distances can increase by 5%.
The other thing is that the softer rubber would wear down faster in the summer, although modern winter tyres are a lot better than designs from a few years ago. But interestingly at temperatures below the critical 7°C a winter tyre will actually wear down less than a summer tyre because the tread slips less.
In fact 7°C is a very important temperature, it is where a traditional summer compound undergoes a structural change at the microscopic level, the long rubber molecule chains start to lock together, hence it feeling more like wood at low temperatures. This means the tread surface can’t move and doesn’t have time to flow into the road surface as the tyre scrubs across the road when cornering, accelerating or braking.
So below this critical temperatures the grip from a summer tyre starts to drop rapidly, as the rubber hardens it needs longer to grip but the hardening tread blocs actually reduce the time available in the contact patch. Everything starts to conspire against it.
At extremely low temperatures the tyre can become brittle, I have seen customers enjoying luxury cars in northern Russia reporting tyres shattering below -40°C as they pull away.
By comparison winter tyres still work acceptably well at -40°C, which is the standard low temperature the whole car industry tests their cars at. But even winter tyres will eventually become hard as the temperature drops even further.
So on a day where the temperature is struggling to get above freezing a winter tyre will out perform a summer tyre by quite a large margin, but even at 5°C there is a noticeable difference, Continental Tyres claim a 7% improvement on a wet road. But when there is snow and ice on the road the winter tyre design works well and the summer tyre looses most of its grip completely, making pulling away on gentle slopes almost impossible and generating entertaining video clips for the news channels.
On the continent it is common to have two sets of wheels for your every day car, new car dealers will store your other set for a nominal fee, usually about 50 Euros so you don’t need to find the storage space at home. This is something we are starting to see in the UK now too. Many people run smaller wheels with higher profile winter tyres to allow even greater flexibility and resilience to pot holes and uneven chunks of ice. This also means your nice shiny summer wheels don’t get covered in road salt and chipped by grit. When buying a second hand car it is easy to pick up a spare set of wheels for your winter tyres to go on, often the smallest wheels offered for your type of car are sold on cheaply as owners upgrade to bigger wheels. When storing winter tyres over the summer it is important to keep them out of sunlight which hardens the rubber and prematurely ages them.
Some people may be tempted to just by two winter tyres, particularly for front wheel drive cars. In the snow and ice having a set of winters on the front of a front wheel drive saloon will make the world of difference, both for pulling away and for stopping. As more of the weight is over the front, which drives and steers the car, the vast majority of the traction is needed right there. At low speeds in such conditions some might argue that the back just needs to follow the front to some extent and so winter tyres are less critical, however nothings ever quite that simple.
When you get to clear stretches of road, having substantially lower grip at the back could get you into trouble, most notably if you have to slow or stop suddenly on any sort of band where the back could drift out. On older cars it would be worse as the rears could lock up and, worst case scenario, send the car into a spin, but as yours has ABS it wont actually let the rears lock up but could still run wide. Obviously this all depends on exactly how ropey your old tyres are, low tread depth and aged hard rubber make things much worse.
For this reason the only ‘safe’ way is to do all four, although having two winter tyres is better than none.
Putting two winter tyres on the back of a rear wheel drive car is much more dangerous, it would then have the ability to pull away on very slippery surfaces but have very poor steering and braking ability due to the summer tyres on the front. It could pull away, accelerate, get to a corner and plough straight on into a ditch. Even on rear wheel drive cars front wheel traction is vital.
But what about four wheel drive cars, do they need winter tyres too? If we assume the 4WD car is on new full tread summer tyres and the other car is FWD with equally new winters on, then the winner when pulling away depends hugely on conditions. On a typical compacted snow/ice British winter road the summer tyres will have very little traction and the 4WD may struggle, but these are precisely the conditions that the winter tyres were designed for and the FWD car will probably get away quicker. But if we throw in some fairly thick slush with tarmac or gravel underneath then the fact that both axles on the 4WD are digging through it may tip the advantage it’s way, the FWD having the extra burden of dragging its back axle through the wedge of clag. In this case a RWD car on winters would suffer even more as the front axle has to be pushed through a bigger wedge than the rear.
But driving is so much more than just the ability to pull away, and once on the move the advantage tips decidedly towards the 2 wheel drive car on winters, every other aspect of traction relies on all four wheels and when cornering or braking the car wearing winters will have a clear advantage.
The example I frequently quote is a Quatro I saw pulling out of an icy T junction last year, four wheel spin and a bit of snaking and it got up to speed, tried to turn right and fell straight in a ditch.
Of course the Quatro on winter tyres would be quite a different storey.
Well that’s enough theory, I tried a set of modestly priced winter tyres from Goodgrip, a Scandinavian company that has just set up in the UK and is used to dealing with tyres for extreme conditions. The Hankook ‘Winter i*cept’ tyres are at the lower end of the price spectrum so I can’t be accused of cheating by buying an exotic tyre. These went on to my trusty Bargain Banger Rover 75, so again no cheating by using advanced stability control etc.
After fitting them we proceeded to experience one of the warmest Christmases on record, but this was in itself a good test and at temperatures a shade above 10°C the winter tyres clearly drifted in corners more than summer tyres, but nothing alarming. It should be born in mind that I was testing the tyres, deliberately pushing them hard and putting them in the most demanding circumstances and I feel that someone driving ‘normally’ wouldn’t even notice this extra drift tendency. Unless of course they had to do an emergency stop, that 5% increase in slip means at motorway speeds the stopping distance increases by approximately one car length, from 20 to 21. So although it’s worse it is by no means catastrophic, even so I would rather use summer tyres in the summer.
More recently we have enjoyed snow, ice and temperatures below -6°C, including a few days where the snow partially melted, froze overnight into sheet ice and had fresh snow over it in the morning.
The winter tyres worked very well, pulling away easily up hill with four inches of snow on top of ice. In fact the snow seemed to help with grip on the ice, bare sheet ice has a smoother surface and presented more of a challenge, but even here the winter tyres were very good. Of course applying too much power or going to fast round a corner will still result in a skid, but as the limit of traction is encountered the winter tyres started to break away more gradually and maintained at least some control of the vehicle.
Their ability was highlighted to me by a colleague who commented that a particular corner we had both driven was very slippery and he nearly lost control, where as I had driven round it as normal with absolutely no problems.
So clearly for every day driving in low temperatures the winter tyre is definitely safer and well worth the expense.
There are some other things worth mentioning too, firstly the softer compound gives a quieter and slightly softer ride. Secondly I got very slightly better fuel consumption. At low temperatures the car will use more fuel anyway for a multitude of reasons, but as a direct comparison on the same route driven in the same conditions (between -2°C and +5°C) the winter tyres on my car averaged about 3% better economy, probably because at these temperatures the summer tyres slip more.
I do a high mileage so this saves me about £2 a week and may save £30 over the winter which offsets the cost of the tyres slightly, a full set for my car was just over £200.
So in summery for an investment of effectively £170 I have a car that is still usable in the winter, much safer to drive, slightly more relaxing and removes that anxiety drivers feel when watching the weather forecast.
I think that is a small price to pay.
As an experiment, and to answer many of your questions, last year I ran a set of winter tyres all year. I do a fairly high mileage, usually about 700 miles a week, and usually I drive reasonably hard, so it was going to be a good test.
The first thing to note is the grip on a warm dry day is very modest, they don’t so much slip as glide when driven hard, drifting deeper in corners. It’s all very progressive an easy to control, and of course if you drive a bit slower you may never notice this trait. But of course emergency manoeuvring and emergency stops will also be less sharp.
By comparison, when I bought the car originally it had some nasty budget summer tyres on, fairly new, but the Hancook iCept winter tyres were better than the budget summer tyres even in the dry. Budget tyres are usually worse at pretty much everything.
So basically the winter tyre was perfectly usable in the summer, not as good as a summer tyre but not as bad as the cheapest budget tyre.
However, the soft compound did wear at a noticeably higher rate. Interestingly the tyre tread area became concave, the centre wearing twice as fast as the edges. This is because the softer compound allows the centre of the tyre to centrifuge out at high speeds, and as I do a lot of motorway mileage it basically took the middle out fairly rapidly. The tyre started with about 10mm tread depth all over, after just over 20 thousand miles and eight months the edges were down to about 4mm and the centre was about 2mm.
So, in conclusion, if you do less than 10 thousand miles a year and don’t drive like a man possessed then a good quality winter tyre could last a couple of years. For everyone else it is better to store the winters in the garage during the summer. Or alternatively use good all season tyres (an experiment I have just started with Goodyear 4 Seasons from Goodgrip), or indeed stay at home for the few days a year when the roads are covered in ice.
I also did some experiments fitting winter tyres to the front and leaving summer tyres on the back, a lot of people asked me about this sort of set up so I thought I better try it for myself. I tried braking mid corner in the worst winter conditions which should be the worst case scenario for this set up, and although the back did drift slightly further out than normal it was nothing dramatic. This was on a Rover 75 which is longer with a lower relative centre of gravity than some of the cars that are sighted as having problems, such as a Fiat Panda, with just two winters on. I think that this may be because the relative lack of rear grip on ice affects the shorter and taller cars more. So although on my test car it worked fine, it does seem to depend on what sort of car is used, it will also depend on the design of the non-winter tyres fitted on the back, mine had good tread depth and large radial grooves which may have helped. So I cannot recommend this format universally, and considering a good winter tyre for an average family car costs less than a full tank of fuel I think it is false economy to only kit out one axle with winter tyres.
In summary, winter tyres – still love ’em.
One of the great problems with a conventional car engine is that most of the fuel’s energy gets thrown away through the exhaust (about 30%) and radiator (another 30%ish), in fact your car engine is lucky to extract 33% of the energy from the fuel, and that’s only at full load, at low loads your petrol engine will be below 10% efficient! So wouldn’t it be great if there was a way of trapping all that heat energy and getting more out of it.
Enter stage left the Sterling engine, invented by an eccentric Scottish vicar in 1823 and now used in many combined heat and power systems for large buildings.
The name is now applied to a whole range of ‘hot air’ engines – the idea is that you have two pistons and cylinders that are connected in some way. A hot cylinder heats up the gas inside it, causing expansion, the gas is then pumped to a cold cylinder and contracts, thus pulling that piston up. As the heat energy can be totally used up by the engine, in theory it could be 100% efficient. Sounds simple doesn’t it.
Small Sterling engines have been made that work on a temperature difference of only a few degrees, so holding it in the palm of your hand makes it work! The trouble is that they are not very powerful for their size because you need a lot of surface area to transfer the heat energy into the working gas in the cylinders. This gas, often helium because of its excellent heat transfer ability, is trapped permanently in the engine. The more gas you have the more energy can be pumped round, improving efficiency, but this requires high gas pressures and very good piston seals which has been the downfall of some optimistic designs over the years.
Because the fuel is burnt outside the cylinders, this is called an external combustion engine, same as steam engines. And as the combustion is continuous, there is very little noise, almost silent. And they can work on pretty much any fuel, petrol, diesel, coal, chip fat or even junk mail.
It’s unfortunate that in practice, complete heat transfer never happens so the total fuel efficiency ends up being only 10% better than a conventional internal combustion engine. But the main benefit comes when the two types of engine are used together, the exhaust and coolant from the internal combustion engine being used to run the Sterling engine, together extracting up to 70% of the fuel’s energy. Obviously this ends up being a big, complicated heavy lump, but that hasn’t stopped people putting it into cars.
A simple version of a Sterling engine has two cylinders driven 90º apart, one cylinder is heated up and the other is cold. The two cylinders are filled with your working gas, possibly helium, and joined by a big tube which contains a regenerator. That is a posh word for a sort of radiator, or heat exchanger, that keeps the heat on the hot side of the engine and the chill on the cold side, this is a very important part and has a massive effect on the engine’s efficiency, a good one will recover 95% of the heat energy.
You may be surprised to hear that one of the most successful Sterling engines was made by Phillips, better known as purveyors of electric shavers and expensive tellys. The Dutch company of boffins started on the design in 1938 but were delayed by an inconvenient world war. The work lead to a very nice portable generator set that enjoyed modest sales success, but the focus of my ramblings this month is the 4 cylinder engine, based on their work and made by United Sterling of Sweden, that was fitted to a Ford Pinto in 1974. The V4X31 used base engine parts from the Saab V4 and was the first car to be driven directly by a Sterling engine. It produced 115bhp at only 3500rpm and worked at about 40% efficiency.
The V4X31 was an early insight for Ford who were working with Philips on a 4 cylinder 170 bhp swash plate engine, that’s where the crank is replaced by a tilted disk, as each piston rod pushes down on the disk; pushing it round in a circle.
Cunningly, in both these engines, they managed to get both the hot and cold cylinders in the same bore, the lower piston having a hole in the middle for the con rod of the top piston. At this point you really need to look at my hastily crayoned diagram, because I am now going to say ‘rhomboid drive’!
Apart from being a great phrase to baffle the pub expert with, rhomboid drive is the way they managed to get both con rods to move up and down with absolutely no side movement, essential when one con rod goes through the middle of a piston, hopefully without any gas leaking out of the hole.
The system uses two cranks in parallel which are geared together at the bell housing end of the block. Each piston has a fixed con rod dropping down to a joint where two articulated con rods are attached, one going to each crank. Who ever thought that one up probably didn’t get out much.
To stop the gas leaking out, which was nitrogen at 150 Bar, the piston seals were nylon sleeves that rolled up and down, a little like rolling nylon stockings down, funny lot the Dutch. It also had the added benefit of having virtually no friction.
Of course the home mechanic could possibly try constructing a simple sterling engine by converting a V twin bike engine to run with one cylinder being heated from the coolant or exhaust from a conventional engine, the other cylinder being water cooled. You could remove the valves from the heads and connect both inlet ports together with the pipe containing the regenerator, which could be an old intercooler cut down, and something similar nailed on to the exhaust ports too. Then belt drive it onto the conventional engine’s front pulley.
It wouldn’t be light but on something like an old Range Rover it could bring the fuel economy up to diesel levels and deliver something like another 50bhp for free. Which is nice.
There have been many stories of genius inventors making a car that runs on water, only to be silenced by the evil oil companies, never to be seen again.
I was intrigued by the sheer volume of technical claims, despite decades working at the cutting edge of automotive technology and being immersed in scientific theory I am acutely aware there is always room for doubt, and for new ideas to surprise and change the way we think. Ideas like these are rare but happen often enough to make keeping an open mind and essential part of the make up of the modern engineer.
The traditional view is that water is basically hydrogen that has already been burnt, so it has no usable energy content left. Because of this fact there is a tendency to think that all these people who believe in water power are all nutters who probably have been abducted by aliens and experimented on for a laugh and are a tiny minority. But nothing prepared me for the depth and complexity of the technical explanations and the shear volume of conspiracy theory’s involving governments, car makers and oil companies all in cahoots to keep us buying expensive oil.
Well, let me assure you that car makers would quite happily stab the oil companies in the back if they could sell a few more cars, and one that ran on water would sell rather well, don’t you think?
So, how do you run your car on water?
Well, you will need a big plastic jar (screw top with a good seal), a small plastic jar, some tubing, a few strips of metal, some small bolts, a fuse and some wire.
But before I go into details, I want to talk about electrolysis. I found a number of amusing web sites that propose the use of hydrogen made from passing current through water. So far that’s not a bad idea, many car companies are investing quite a lot in converting petrol engines to run on hydrogen.
Where these sites go off the rails is when they generate the gas on board the car, using electricity from the alternator, which is of course powered by the engine.
Here are some basic figures for you, a good car engine will convert 33% of the energy released from the fuel into usable power at full throttle, it goes down to about 10% at light loads. An old carb engine might be as poor as 20% at full tilt. Oddly enough big engines can be more thermally efficient than small ones, its all to do with heat loss and the ratio of volume vs surface area, the most efficient piston engines in the world are the cathedral engines in super tankers, such as the 25 thousand litre Wartsila-Sulzer RTA96-C turbocharged two-stroke 14 cylinder, which gets up to 50% efficiency. You may recal I did a blog post about it last month, its very impressive but at 2300 tons you would struggle to get it in a car.
So, going back to our in-car hydrogen plant, with the precious little power left at the crank we drive the alternator, which usually has quite a good efficiency, converting about 90% of the power fed into it into electrical energy.
Then there is electrolysis, at the molecular level, the energy you put in to separating water into hydrogen and oxygen is the same energy you get back when you set fire to it. Interestingly, some of that energy can come from heat from the environment, ie the heat from the engine.
So, when you add up all those efficiencies up, to produce 1bhp worth of hydrogen, the engine has to burn nearly 4bhp worth to make the process work.
Guess why it doesn’t work!
Mind you, if you generate the electricity away from the car, say from a wind turbine in your back garden, store the gas in huge explosive bags attached to the roof of your car then you are on to a winner. Until it imitates the Hindenburg.
So once again I have shown that you can’t run your car on water. So now I will finally get round to showing you how to do it.
One of the reasons that the efficiency of car engines is so low is that not all the petrol gets burnt, and some gets partially burnt. The actual combustion process is very complicated, with molecules decomposing into sub species before reforming into exhaust gasses. The flame front travel across the cylinder is also semi-chaotic and some molecules get passed by entirely. Some start burning then hit the cold cylinder walls and stop burning, some start burning at the end of the process when the piston is to far down to convert it into usable energy. Petrol mixtures burn at a rate of about 40 to 50 centimeters per second depending on loads of factors like pressure, turbulence and temperature. That’s one of the reasons that big engines run slower as it takes longer for the flame to travel across the bigger combustion chamber, for instance that super tanker engine I mentioned produces 5 million ftlb of torque at just over 100 rpm.
If we could speed up the burning process then more of the petrol’s energy can be converted into useful work on the piston. Also, if we could put in something that would mix more readily with the air and bridge the gaps in the fuel mixture we could avoid those dead spots.
Ooh, hydrogen does that, it mixes very readily and burns faster. So all we need is a very small amount of hydrogen and we can improve the efficiency of the petrol.
Well, if its so good why hasn’t it been done before? Well, it turns out that this method has been used for many years and some reasonable research has gone into it, have a trawl through the SAE web site and you will see that many respected institutions and big companies have published papers on the subject. Some use methane which is broken into hydrogen and carbon dioxide by the use of rather hot steam. Of course you then have a hydrogen car that produces co2 which is sort of bad really.
So here is the theory; you get a bucket of water strapped to the car, stick two bits of metal in it (electrodes) connected to the battery (via a switch and fuse). The lid on the bucket has a hose to transport the explosive hydrogen and oxygen gas to another bottle where any water is removed (don’t want to hydraulic the engine). Finally the hose is stuffed somewhere in the intake to allow the gas in.
Great, but how much gas do we need? Well, to make 1g of hydrogen you need to apply 285Kj of energy to the water, luckily the water tends to use energy from the environment during the process, so potentially about 48 Kj of heat will come from the engine bay, leaving our electrics to provide about 237Kj per gram.
Now, power in Watts is Joules per second. So 1.4Kw (1 HP) is 1.4Kj per second. Which works out equivalent to burning about 0.006 grams of hydrogen per second, or in volume terms that’s about 0.066 litres per second, a steady stream of small bubbles.
So for a cars electric system to put in 14Kw of power at 14v the current will be 100 amps, which is a lot.
But remember we are not talking about using the hydrogen to power the engine, but to help get more useful energy from burning the petrol. So the big question is how much do we actually need? The web sites suggest one litre of water will last up to 900 miles. That works out at about 1.1g per mile, and of that 1.1g of water there is only 0.12g of hydrogen per mile. At average speeds this works out at about 0.0013g/s, about one fifth of a bhp, less than 1% of the overall fuelling and will draw about 10 amps in the electrolysis bucket.
To get a sensible answer to all this, I nailed some scrap metal into an old washing powder tub and tried out some combinations.
The first version was one recommended on an American web site, claiming up to 40% gains in efficiency. It consists of a one litre plastic container with two bolts in as electrodes. But even with a little salt added to my copy it only managed to draw 0.1 amps and no detectable gas flowed out of the outlet hose. In short, it was useless and had no effect on the engine.
Clearly we need more power, one of my favourite sayings. So next we have a system with drastically increased conductor length by using wire, wound round a cross shaped former, still in the one litre pot. This has the effect of drawing 10 amps, about where most of the internet products are, and a steady stream of bubbles.
This very small amount of gas will have the most dramatic effect on the engine at lower loads and idle because that is where it will be the biggest proportion of the total mixture, so I fitted the system to the intake and watched the injector pulse widths and lambda compensations so see what effect it had. Well, the web sites suggest a 30% fuel saving overall, so at idle it must be huge, but no, there was absolutely no difference on average.
I even drove it round for a few weeks, and at first I though I could just detect an improvement in power and the fuel bill seemed to be dropping. But then it went up again; it turned out that it was just me driving more carefully as I paid more attention to what I was doing after fitting the kit. This is a very common phenomenon.
So how much gas do I need then? Well, some very useful research has been done by NASA and various universities. Basically to get a 30% increase in efficiency (power out vs fuel in) we need to run 90% hydrogen/10% petrol!
At 50 % hydrogen the efficiency improvement is only 15%, but what does that mean in a normal car? Well, if you are cruising down the motorway you might be using about 20kw of engine power, if you only run 50% HHO then that’s 10kw of electricity running through your jam jar, at 14v that’s over 710 amps out of your alternator! But then that power comes from the engine so it would now have to produce over 30kw, which would mean a 30% increase in petrol use in order to gain a 15% efficiency saving….. Hmmmmm..
Now, bear in mind that the average driver can improve their fuel economy by up to 30% just by learning better driving techniques, and that on an average commute fuel economy can vary by 20% easily depending on what mood the driver is in. So subjective assessment of 10% economy gain is meaningless, it has to be checked on a proper test facility.
There are of course other ways of generating hydrogen on board a car, using chemical reactions, and this would take the alternator problem out of the loop, but generally the chemicals are rather nasty/expensive and leave a chemical waste problem.
One of the favourites being explored by the car industry is called ‘reformate’ where the petrol is partly separated into CO2 and Hydrogen using a catalysts and exhaust heat. At the moment the fuel savings don’t justify the expense of the extra equipment, but I am sure that will change in time.
Water has a number of other benefits in a traditional engine, I am sure you know about water injection which turns a bit more of the heat energy from combustion into pressure energy. It also reduces cylinder temperatures and so reduces knock, allowing a bit more advance. But also a small amount of water, up to 5%, if well mixed in the fuel before its injected can increase power by up to 7%. Unfortunately you cannot just chuck a cup of water in the fuel tank, because it wont mix, you need some reasonably clever and accurate mixing machinery.
In short, there is a lot you can do with water. However, if you google ‘water car’ then the myriad of websites that appear generally talk complete twaddle and make excessive claims for there own brand of hocus. Whilst I am talking about the web sites, there were a few claims that I feel are potentially harmful.
First is the matter of your cars warrantee, unlikely anyone thinking of doing this will have any, but the point is that despite the various web site claims, fitting absolutely anything to your engine will invalidate the warrantee. In the car industry we spend a huge amount of time and effort checking the car works under all sorts of conditions, it takes years for each model to complete all the tests before being ready for production. Modern engines are so finely tuned that any disturbance will cock things up, and that includes those plug in chip tunes by the way. So plumbing in a bottle of water to your intake will definitely lose any warrantee.
Next, some sites sell you electronic devices to bias engine sensors to make it run lean, best fuel economy generally happens when you run 10% lean of stoich, which is fine at part load on a non cat car, but obviously not at full load because things overheat and fail, and if you have a cat it will stop working eventually. And as these are sold without checking the engine on a dyno the potential for detonation or catalyst damage is rather significant.
Then there is the matter of additives in the water, remember it all goes somewhere and some chemicals will put quite nasty things into the atmosphere. Some sites advocate volatile fuel additives too, again the reason the car industry doesn’t do this is that it poisons the catalyst and puts very nasty stuff into the air. Fuels with super chemicals that don’t pollute as much are readily available, such as Shell Optimax or BP Ultimate which have over 200 chemicals in to get the best performance.
Safety seems to get a fairly low priority too. Remember that as we separate the water we get a perfectly explosive mix of hydrogen and oxygen, albeit in very small amounts. If the pot you generate the gas in is not ventilated then any slight spark could leave you pot-less and potentially destroy things under the bonnet. Luckily most of these systems produce so little gas that it is unlikely to be a problem!
So in summary, yes you can run your car on water, but not using a jam jar and some wire.
Don’t just take my word for it; here are some of the research papers I used in my research:
SAE 841399 1984
SAE 740187 1974
Lean burn with Hydrogen supplementation
General Motors Corp.
SAE 810921 1981
Lean burn with Hydrogen supplementation
University of Michigan
Hydrogen reformate (H + CO2)
Robert Bosch GmbH
SAE 760469 1976
Hydrogen reformate in aircraft engines
Jet Propulsion lab
What are the losses?
The heat released from fuel is mostly wasted, about a third goes down the exhaust pipe (turbos can recoup a small fraction of this) and another third goes into the oil and coolant. A smaller amount is wasted as noise and vibration.
At part load the throttle causes an obstruction that wastes power too. A better solution at part load is to replace the unwanted air with an inert gas, this allows the throttle to open up and reduce losses. That is why Exhaust Gas Recirculation (EGR) can improve economy by 5%.
What is reformate?
This is where the petrol is broken down into hydrogen and carbon dioxide. The CO2 is inert and at part loads is used as ‘padding’ allowing higher throttle openings, this reduces the throttle losses and also improves efficiency. This double benefit is why the car industry is concentrating on this way of making Hydrogen. But with the petrol engine’s days numbered, the technology may never mature.
What is HHO, Oxy-hydrogen or ‘Browns Gas’?
This is what you get from electrolysing water, it is simply oxygen and hydrogen in a gas. There is a lot of myth about it, but here are the facts: It burns at about 2800 C, compared to about 2000 C for petrol in air, or about 3000 C for oxyacetylene welding kit. In fact it was one of the first gasses for welding, but in slightly richer proportions. When HHO is burnt in air, as in our engine example, the flame temperature drops to similar values to petrol.
When it burns it expands, and so can be used to power piston engines, then it forms water vapour and starts to condense, rapidly contracting into just water.
The gas has been the subject of many hoaxes, frauds and misguided optimistic claims.
It’s not magic, just nature. Although personally I thing nature is pretty magic.
There was a time when ‘Jaguar’ and ‘V8’ could not be uttered in the same breath, which is odd when you consider the majesty of the Daimler 2.5 and 4.5 V8s used since the ’60s.
But by the end of the ’80s it was becoming clear that the weight of the gorgeous Jaguar
V12 was just too much, plus its enormous physical size was hampering car design, particularly for crash performance where you need some crumple zone rather than solid engine. The engine was revolutionary in the ’70s, but in the ’80s the labour intensive assembly and expensive parts was costing the company more than it was making. For the last years of the XJS the V12 was not even on the official brochures, it was only its legend that was keeping sales alive.
The AJ6 and AJ16 6 cylinder engines were making almost the same power and saved about 120kg which made a huge difference to the cars handling. But even this engine was showing its age.
New shorter engines were needed in order to allow sufficient room for an effective crumple zone. The engines needed to warm up more quickly, for both customer comfort and the ever tightening emissions regulations. This needs more precise cooling in the heads and block plus the use of considerably less metal. The piston ring system needed to control the oil much more accurately and piston friction had to be lowered. Indeed, friction throughout the engine needed to be reduced to meet the fuel economy and emissions targets.
With these issues in mind, a number of alternatives were looked at in the late ’80s, including a V12 derived V6 with the lost power being returned by using a brace of turbos. Another V6, an Orbital 2 stroke engine which gave the same number of power strokes per rev as the old V12 engine, was looked at but oil control and refinement never quite met the targets. They even looked at a number of engines from other companies, which could be bought in without the huge cost of developing their own engine.
During the dreaded BL days there had been some discussion of using the Buick derived Rover V8, which had substantial advantages in terms of weight (in fact it weighed half as much as the V12), cost and size. Unfortunately, most of the advantage came from the fact that it was relatively thin walled and so suffered in refinement a little. But in reality this could have been developed out, as was the case in the final fling of the Rover V8 inside the P38a Range Rovers.
But that venerable V8 was itself a relic of the ’60s and ultimately suffered from the same issues as the old Jaguar engines, in terms of efficiency and emissions. It also struggled to meet the power demands of modern cars, the 4.6 version only putting out 220bhp.
So the bold decision was made to design a completely new Jaguar engine, one that would meet the forthcoming challenges of regulations and customer expectations. Originally code named the AJ12, the project used a single cylinder research engine to examine a number of different combustion chamber, cylinder head/ port and cam options. This data showed that a 500cc cylinder with 26 degree ports and a four valve configuration gave the best economy and performance for Jaguar applications.
Although AJ12 never resulted in a physical engine, the data was used to study a modular engine design concept, concentrating on a 4 litre 8 cylinder and a 3 litre 6cyl, but also looking at a 2 litre 4 cylinder, a 5 litre 10 cylinder and a 6 litre 12 cylinder engine. This would require some rather sophisticated machinery to be able to make all those variants, sharing common components such as piston and valves but little else. As the analysis data grew, it became clear that the complexity of doing all those variants would be crippling, so it was decided to concentrate on 6, 8 and 12 cylinder V engines. Thus the project now became known as AJ26, 26 being the sum of 6, 8 and 12.
But this would be hugely expensive, the fuel bill alone for testing engines runs into millions of pounds per year. At this time Jaguar was privately owned and as such there was simply not enough spare cash to invest in new products. What was needed was an owner who could suffer the financial hit in the long period between investment and return.
When Ford became interested in buying Jaguar, it was only natural to see if one of their many engines would fit the bill. Indeed it was not uncommon for Jaguar owners in the USA to retro fit a Yank V8 so there was some precedence for this already.
But work had already started on the fledgling Jaguar V8 and the Whitley team, lead by Dave Szczupak, were passionate about seeing it through, they had looked at all the requirements and designed something that would give the legendary levels of Jaguar refinement and power whilst being small, light and efficient. But there would be a long road to go, from a concept to a fully customer ready production engine. Typically it takes around 7 years, that’s a long time to ask an investor to wait for a return.
Ford looked at the arguments for both Ford engines and for the new Jaguar engines, after all the data was analysed and the requirements understood, they decided to invest the millions needed by Jaguar to make their own new engine. But this would be dedicated tooling for just the V8, all other variants were not to be.
The first year had been largely given over to defining the requirements, the specifications for each part of the engine such as how much heat goes into the coolant and the oil, how much force is needed to turn the engine over, valve train stiffness, noise levels as well as the major things like the power and torque levels.
This had lead to the basic design, this was put into the new computers and virtual tests run to establish the best coolant flow paths, the best inlet and exhaust port shape, the cam profiles and the such. A huge amount of data was produced and analysed, without making a single engine. Somewhat different to the early days of the V12 when development was a matter of calculated guess work and then lots of test engines trying it all out.
The calculation gave most of the answers, but some elements still required real world testing. To this end some elements of the new engine were experimented on in isolation, using a current production ‘slave’ engine as a base, giving rise to some odd reports in the press of the new engine being based on this that and the other engine. For example, in order to try different bore and stroke combinations on the single cylinder rig, the engineers looked about for existing parts from all sorts of manufacturers, at one point it was using a Peugeot piston and a Mazda con rod!
The first V8 engines were run on test beds in late ’89 and the first car to receive one was an XJ-S, one of the cars that had just finished being used to evaluate the twin turbo AJ16 in fact. As is always the way with the first ever engine installation, nothing fits, mounts, hoses, air intake and exhaust manifolds all had to be fabricated for the job. Steve, one of the mechanics on the job, recalls ‘they gave me a bag full of exhaust tube and various bends and told me to get on with it’. At the end of ’90, after a couple of weeks of trial and error fitting work the first 4 litre V8 Jag burbled into life and was universally admired by the small select audience of management privileged enough to see it, particularly in America which was a crucial market.
It weighed about the same as the old 6 cyl but had more power and a greater spread of torque, thanks to the new variable cam timing system. But there was a small problem, it didn’t sound like a ‘Jaguar’. Although very appealing, the V8 burble sounded like any normal mid size car in the USA and part of the Jaguar magic was the very high levels of refinement and quietness. Sound is such an emotive thing and much debate was had as to what the new engine should sound like, eventually the decision was made to make it quiet and an enormous amount of work went into designing complex intake and exhaust systems. It is interesting to note how this has changed now such that the current XKR even has a device built into the bulkhead to help you hear the engines magnificent growl.
The first car I drove with the new V8 was an XJ40 in about ’93 at the Ford research centre in Dunton, Essex. The car was based on the XJ12 body, code namedXJ81, which had completely new metal work in front of the bulkhead in order to accept a V engine. This car was bristling with new technology, it had one of the first electronic throttle systems and this particular car had a manual gearbox but with an automatic clutch. As you shifted gear the systems would move the throttle and clutch so as to give you smooth gear shifts. It was marvellous to drive but ultimately it was easier to just use one of the excellent ZF 5 speed auto gearboxes instead.
Its interesting to note how Jaguar has had a history of technological innovation, and how right from the start Jaguar was showing Ford new things. In return Ford showed Jaguar how to massively improve production processes, improving quality and reducing costs. This relationship is continuing to this day, I am pleased to say, with both sides benefiting.
As the engine developed, the early tunes were used to check and refine the basic performance and emissions characteristics. Then cars were used to tune the transient response, that is to say how the engine responds to acceleration, deceleration and gear shifts. This is always a very difficult balance between good drivability and good emissions, a slightly rich fuelling on acceleration give very good drivability but will fail emission completely on hydrocarbons alone.
Part of the solution was to ensure the automatic gearbox control system ‘talked’ to the engine control system. This kept the throttle, fuel and spark precisely in tune with the change in engine speed during the shift, allowing the engine to anticipate the changes rather than have to react to them after the fact.
After the engine had received a good stable tune, it was time to test it in all the harsh climates it would face in the real world. Traditionally this involves driving it in the Arctic and in the deserts of Arizona or Africa. But now tests could also be done in Fords climatic test chambers which drastically cuts down the development time and expense. As well as cold and hot climate tests, the new cars had to be tested in extremes of damp to check the corrosion resistance of the components and all the wiring. Then there is the rough road testing, both on specially prepared test track with a range of harsh surfaces, and on shake rigs where computer controlled hydraulic rams try to shake the car to pieces. In short, a lifetime of use and abuse is concentrated into a matter of months. By the end of ’94 a huge amount of data had been produced and all the necessary changes had been made, the results were looking very good indeed.
After this year of climate and durability tests, the final tweaks could be made and then it was time to start running the cars at government approved test centres to get the various certifications needed to sell a new car. At the same time further tests were re-run in house just to confirm that the final version was working as expected.
In parallel to all this development, the production plant was tooling up. First prototype tooling is made and the whole assembly process is tested, any special tools or assembly methods are identified and the first set of workers are trained. The first few test cars were built this way, as were the cars eventually used for the journalists to drive at the launch in ‘95.
The cost of production tooling is huge, the Bridgend AJV8 plant cost Ford £125 million. So it was vital to be certain that everything was right before the orders were placed, this could only happen when all the test data was in and all the tweaks had been tested. This is still true today and is one of the reasons it takes so long to get a new idea into production.
So, in ’96, seven years after the project started, the first XK8s were sold with the all new, entirely Jaguar, V8 engines. A new era had begun.
The original 4.0 litre V8 went through many detail revisions, and endured the dreded Nickasil debarkle that struck many alluminium bored engines of that era. All the lessons learnt were rolled out together in the later 4.2 litre version of the engine, this unit has a reputation for toughness as well as performance and has been raced with some success too. When Land Rover joined the group it was a natural choice to replace the less than reliable BMW V8 with the trusty and powerfull Jaguar unit. In Discovery it was stretched to 4.4 litres in naturally aspirated form but was left at 4.2 for the supercharged variant, 400bhp seemed perfectly sufficient for a Range Rover back then…..
As with all technology in this rapidly changing modern world, eventually it needed a rethink to regain ground lost to competitors who had brought out engines with the latest innovations. The very name ‘Jaguar’ conjures thoughts of tradition and heritage, but it is easy to forget that a fundamental part of that tradition and heritage is innovation; pushing the boundaries back and surprising the car-buying public. In the 70s and 80s, arguably they made the world’s only mass production V12, and at its launch the XJ6 set new standards in refinement and performance coupled with superb looks and all at a very reasonable price. And whatever you may personally think of the XJ-S, it was a very bold move and still has a very strong following.
The all new AJ-V8 GenIII five litre V8 engine demonstrates the continuation of that innovative tradition, capable of delivering over 500 bhp in a selection of very civilised luxurious cars. And as a demonstration of the engine’s strength, a basically standard engine, a tad over-boosted in a slightly modified XF-R was driven at 225.6 mph on the iconic Bonneville salt flats, faster than the XJ220 super car.
It is interesting to draw a comparison with the magnificent old Jaguar V12, intended to provide approximately 20% greater performance than the 4.2 XK six cylinder engine of the time.
In a similar way, the new AJ-V8 5 litre replaces the 4.2 V8, and pushes power levels up by similar amounts; from 420 to 510 bhp for the R version. However, some things are radically different this time round; the new larger engine manages the rather impressive trick of being significantly more economical than the engine it replaces. An astonishing achievement but absolutely essential in today’s, also radically different, environment.
The V12 was also very advanced for a road car engine at the time, in both its concept and manufacture; it was all alloy and designed for fuel injection from the outset, although they were forced to run carburettors temporarily on the E Type. By comparison the new V8 also uses the latest materials and sports an advanced fuel injection system which heavily influenced the engine design, specifically the cylinder heads with a central fuel injector in each combustion chamber.
The injection concept was proved out before any prototypes were made, on a highly modified current production engine taken out to 4.5 litres. The first real prototype engines were created in 2004 and were immediately and relentlessly tested in engine dynamometers, where each engine can be tested in isolation under precisely controlled conditions. Some engines did specific tests such as trying to deliberately foul the spark plugs, or push the performance limits, and others were run on durability cycles designed to stress components to the max, many a time I walked past a test cell where the exhaust manifolds were glowing bright orange as an engine was run at full tilt.
It is of course the people that really make a company, such as the crack team of expert technicians who build and prepare engines ready for testing, often covered with so much complex test equipment that the engine is totally obscured. Or the chaps in the dedicated powertrain machine shop, a small room packed with tools to weld, cut and machine almost any component, often at short notice, using a mix of the ultra new and the traditional techniques that have served Jaguar engine development for many decades. Research by its very nature involves the unforeseen and as a team, their resourcefulness and creativity has saved many a day. It is the talents of dedicated people like this that form the ‘DNA’ of the company.
After initial assessment of the engines, it soon became clear that the naturally aspirated version would meet its performance targets with ease, something that is quite rare in the rest of the car industry, and the supercharged version could exceed expectations without effort so the original power target was raised from 500 to 510 bhp.
The first car I drove with a prototype engine, in 2007, was one of the first engineering ‘hacks’ and so the engine tune was still splendidly raw. It is from this point that skilled engineers start refining the car’s response, making the car do what the driver wants rather than just reacting to crude mechanical inputs. Before work could begin, this particular car had to be driven from Gaydon, where it had been assembled, to Whitley for testing. As I was making that journey myself I volunteered to take the test car, unfortunately it was pouring with rain and as yet there was no traction control – this lead to a few moments of unintentional entertainment and a degree of sideways progress, but even at that embryonic stage it was still a wonderful car to drive.
Indeed it is an essential part of the vehicle’s development to test drive in every type of likely environment so that the design can be finalised before test cars are sent for official emissions certification all over the world. So cars are out and about with disguise kits on years before launch, trying to avoid the hoards of press photographers camped out in the hedges near the factory. Whenever ‘spy shots’ of a new car are printed, it’s standard practice to work out who was driving and then mock them mercilessly, although sometimes it can land the driver in real trouble if more is revealed than is wise.
As ever, refinement is an essential Jaguar characteristic and this has been achieved by ensuring the moving parts are perfectly balanced in the traditional manner, but also with the new Gasoline Direct Injection (GDI) system, where the fuel is forced directly into the combustion chamber at very high pressure. It controls combustion in such a way as to minimise vibration and noise, effectively by shaping the way the cylinder pressure rises, as well as reducing emissions, better fuel economy and higher performance as if the system raises the fuels octane rating. The whole engine is designed round the system and a lot of hard work ensures all the different factors work in harmony, from the computer synchronised high pressure pumps to the crystal operated injectors that give a sequence of perfectly formed fuel pulses.
The technology has near magical control, when you hit the start button the engine will synchronise, analyse the current air and coolant temperature, check the oil level and temperature, check all the sensors are working, set the fuel pressure on the twin double-acting high pressure pumps, check and adjust throttle angle, set all four cam positions, charge up the ignition coils and the 160 volt injector control circuit and be ready to fire the first cylinder within one revolution of the engine.
And it’s not just the engine that makes for a stunning drive; the gearbox is a lighter yet stronger version of the ZF 6 speed which works in a detailed and complex harmony with the engine, exchanging data and requests in a high speed electronic conference. For instance – when changing gear the gearbox asks the engine to adjust power to balance the kinetic energy left in the drive train and so removing any cause for a jolt or surge, it all happens in a fraction of a second, all for your driving pleasure.
It’s all very impressive stuff and a million miles away from the possibilities available nearly 20 years ago when the design of the last V8 started. The sheer volume of work that goes into the new engine merits a celebration: so for the privileged few of you who get to drive one of these wonderful cars, please take a moment to look under the bonnet, a lot has gone into that modest space.
I was hearing about some chap who ran his car on Biodiesel and had a few engine problems, the engine would loose power and display the legendary ‘Check Engine’ light prompting him to take it to a dealer to have the fault codes read. There were many fault codes set, mainly due to various blockages, which lead the dealer to change a number of expensive components that in truth were perfectly ok. His conclusion was that
manufacturers must design the fault detection system to generate revenue from needless parts sales, this is of course complete cobblers, not least because manufacturers always loose heavily when any part is changed under warranty. But also bear in mind that thousands of us Engineers work developing these systems and on the whole we are not a bunch of psychopathic con artists with a hatred of the driving public! On the contrary, most of us are car enthusiasts and obsessed with doing thing right.
So how did this bloke end up in that situation, and what strange sequence of events led him to his disparaging conclusion?
Well, Biodiesel made to BS 14214 contains a fairly high amount of solvents which can cause issues
in cars that have run on ordinary diesel for some time. Wax and other deposits can build up a bit like those fatty deposits you get inside dishwasher drains, but the solvents in biodiesel clean out the tank and fuel lines causing the debris to float off and block the fuel filter (which is only doing its job). Common practice when deciding to run on biodiesel is to fit a new filter first, run the car for a short time to flush things through and then fit another filter; they generally cost only a few pounds. But on this car that wasn’t done and the fuel flow became restricted so when the demand was high the engine would loose fuel pressure and reduce the power level to compensate, to the driver the car drove normally until accelerating hard to overtake when it would suddenly loose power.
A fuel pressure fault would be flagged but international fault code listings are, by their very nature, quite generic which works well for most problems, but in this example the system would only be able to detect that the fuel system pressure had dropped as the demand increased when he was overtaking. As soon as the engine had been restarted the pressure would return.
Once the engine has been restarted a few times the system must assume the fault has been repaired, as there are big penalties for manufacturers if their cars keep flagging false warnings, and so by the time the diagnostics tool was plugged in the codes may have been cleared automatically. So when our chap went to the dealer there would be no trace of the fault code for de-rating, just some ones about fuel pressure which lead to the dealer mistakenly replacing the fuel pump at great expense which obviously would not cure the blocked filter. The customer took the car away and unsurprisingly the same problem occurred, so he took it back to the dealer.
In this case the dealer stated that as well as the generic codes there are manufacturer specific codes that can only be read by the manufacturers own diagnostic equipment, so the system was hiding information and it wasn’t their fault. This is unfortunately what started the conspiracy theory!
Manufacturer-specific fault codes are there as an extra layer of sophistication and reflect aspects of the engine system design that are unique to that manufacturer and that particular type of engine. They are even more open to misinterpretation which is why car companies are keen to only give them to people who have been properly trained. So yes; there is a separate fault list, but it’s not some secret conspiracy, just a reflection of the very high complexity of modern control systems.
It could well be that the garage personnel had difficulty understanding the diagnostics which is entirely understandable as the systems are hugely complex and every car is different. Not only that, but the technology is changing all the time, so having an understanding of common systems available five years ago is of very little use on cars of today. This complexity is driven by emissions legislation, safety requirements and customer demands whilst reducing costs, it is done out of necessity. Modern engine management is one of the most complex and demanding control systems commercially produced, and yet this feat is hardly recognised, which is a shame.
So the moral of the story is two fold; there is a skill to interpreting fault codes and they need to be used in conjunction with traditional fault diagnostic techniques (ie: if there is not enough fuel getting through, check for blockages!), and manufacturers don’t design in faults deliberately, it’s hard enough as it is!
One in a million.
My boss told me “so that means your design will defiantly kill two people per year!”.
That was 20 years ago, when I was a fresh faced engineering graduate in my first job at a global car maker. I was designing bits of engine management system, and as ever I had gone through every type of conceivable failure and worked out how well it was protected against. But one very obscure scenario involved the car stalling on a hypothetical level crossing near a strong radio transmitter, a bit tenuous but it is a situation that could happen, I had gone through the figures and worked out that it was a million to one chance that the engine would not restart, resulting in something bad involving a train and sudden localised distortion to the car (ok, a crash).
I thought that this was a remote chance, but my then boss pointed out that the systems would be put on about 2 million cars per year in Europe, hence his terminal conclusion.
I redesigned it. No one had to die.
But even so, I am sure there could be even more obscure situations I had never even thought of, I probably could have spent years going through more and more complex scenarios, but the the car would never have been made. So we have to draw the line somewhere.
How common are uncommon faults?
Cast your mind back to Toyota’s ‘sticky pedal’ problem, millions of cars work fine yet a handful of unverified complaints necessitated a total recall. You just can’t take chances, even if almost every car is perfect.
Of course Toyota are no worse than Ford, Mercedes and all the rest, all volume products suffer from occasional problems, largely due to the scale of production and of course because we want our complex cars dirt cheap, and that’s not going to change any time soon.
When an industry has to make very complicated machines with highly sophisticated features that are used by the general public who have only minimal training, and have to endure a vast array of harsh environments including salt spray, Arctic freeze, road shocks and days on end in scorching sun, things are going to be difficult. And when this problem is massively compounded by having to make the car as cheap as possible, something has to give.
Times this set of problems by the millions of cars made every year and the law of averages is definitely not on the side of car makers. If you think about it, the mere fact that when something does go wrong it makes the headlines tells us something about the utterly fantastic job that all these companies usually do.
If the average Joe knew anything of the vast amount of sheer hard work that goes into creating cheap, economical, useful and reliable cars they would bow down in reverence, and those that fancy their chances at suing for spurious accidents would hang their head in shame.
But hardly anyone knows about all that fantastic engineering work, it doesn’t make sexy TV programs, it’s not vacuous and glamorous enough to make it into the glossy magazines. So every one just accepts that every machine should work perfectly no matter what, and are utterly surprised on the very rare occasion that it doesn’t.
So how often do things fail? Well things are much more likely to go wrong when any product is either new or reaching the end of its designed life, the first few miles a car experiences show up any glitches in production and then once these are sorted most modern cars will trundle on for over a decade without significant problems (assuming its correctly maintained). During the cars early life car makers measure things in returns per thousand and generally they run well below 5, that’s 0.5% of cars having any sort of fault at all in the first year of ownership. Good models will run at less than 0.005%, and these faults could be anything from a cup holder breaking to an engine failing. The trouble is that if you churn out a couple of million cars a year then even these tiny numbers mean there will be hundreds of failures in the field, unfortunately these make good stories. Manufacturers hate even these small numbers of faults, obviously every company’s dream is to have no failures at all, and indeed some models achieve this, and they are all striving to eradicate all potential for failure. But occasionally I think its a bit sad you will never see a headline reading ‘millions of car turned out to be pretty good actually’.
Cars are amazing.
Here’s a challenge for you; think of a machine that has to work in heavy rain, baking sun, snow, ice, deserts, be precise on tarmac yet still cope with cobble stones, Suffer grit and gravel being blasted at it from underneath and do a huge range of complex mechanical tasks at temperatures between -40 to +50 C, last over a decade whilst being shaken, accelerated, decelerated by novice users in a crowded and complex environment.
There are no other machines, just motor vehicles, which have to contend with all this.
But it doesn’t stop there, the engine is retuned every combustion cycle, hundreds of times each second in order to meet the incredibly stringent emissions laws, pollutants are measured in parts per million, the tests are so sensitive that simply exhaling into an emissions test machine would cause the limits to be exceeded (note; these are not the simple emissions testers used at MOT stations, the MOT emissions limits are laughably lax by comparison to the certification tests the manufacturer has to do).
To give you a very rough idea of the amazing computing power needed to control and engine to these limits, a modern engine control box (ECU) may have around 25 thousand variables, tables, maps and functions. It calculates mathematical models of how the air flows through the intake system, how the pistons and valves heat up and how the catalysts is performing, it analyses the subtle acceleration and deceleration of the flywheel every time a cylinder fires, it listens to the noise the cylinder block makes and filters the sound to decide if the engine has the slightest amount of knock (in fact some engine deliberately run the engine into borderline detonation to extract maximum efficiency). It talks to the gearbox to anticipate gear changes and control torque so that the gearbox ECU can precisely control the energy input into the drive line during a gear shift. It analyses the long and short term behaviour of every single sensor and actuator to automatically compensate for ageing and wear as well as diagnosing and compensating for any faults.
But it doesn’t stop there, on some cars the suspension analyses the road and adapts to suit, the auto gearbox monitors the drivers ‘style’ and changes the way it works to please them. The brakes check wheel speed thousands of times a second and deduce when a tyre is about to skid, not when it already has started skidding, and relieve brake pressure just before it happens to ensure the tyre provides maximum grip and stability.
The climate control breathes in cabin air through tiny aspirated temperature sensors and adjusts valves and flaps to discretely meet your comfort needs. The stereo selects a nearby station as you drive along and seamlessly switches in so you never have to retune in order to continue to listen to Radio 2 on long journeys. All sorts of things are controlled and monitored from fuel pumps to light bulbs.
All in all an average family car might have between five and ten computers working together, sharing information and jointly controlling the car, a typical example would be the ABS unit supplying road speed info to the gearbox so it knows what gear to select. Luxury cars can have over 50 different computers, even the seat heaters have self diagnosing control brains in and talk to the car on a serial bus, and they all interact with things like the battery management systems which may at any time request all these systems change the way they are operating in order to cope with some adverse situation.
The way these systems work together can be very complex, for instance stability control uses the ABS system to apply brakes on individual wheels in order to pull the car to one side as well as requesting a certain wheel torque to ensure the car goes in the desired direction, this torque is controlled by the gearbox and engine working together too, the engine can react almost instantaneously by altering the spark angle (these events happen so fast that the engine has to wait for the airflow to reduce going into each cylinder even though it moves the throttle immediately, because of the air’s inertia!).
Components have to operate faultlessly for millions of cycles, if an engine or drive-line fault develops then the systems must identify it, adjust the mode of operation to minimise risk to car and people, and alert the driver, just like having an expert mechanic on board.
In addition the car has to be comfy by isolating key frequencies from being transmitted by the suspension and engine mounting systems, prevent wind noise from the gale force breeze rushing past the shell, stop the metal box that makes the cabin sounding like a metal box and muffle the many kilowatts of noise running through the exhaust pipe.
It also has to be economical, using every drop of fuel sparingly, compromising the shape of the car itself to reduce drag whilst still allowing enough space to get everything in and have enough air flow round the hot bits to stop them degrading.
But as well as being frugal it also has to perform well, even a modest family hatchback these days has the performance of a race car from the ’60s, indeed there are many saloons with well over 500bhp now, compare this with the 1983 F1 race winning Tyrrell with 530 bhp. Yes our super comfy mobile entertainment centres have the performance of an older Formula 1 car.
And not only does it have to balance all these driving related tasks but it also has to have a really good sound system and have most of the comforts of home, some even have cup holders and fridges.
Not even the Space Shuttle has to contend with this level of sophistication. I can’t see rockets running catalytic converters and exhaust mufflers any day soon.
And here is the kicker; as well as coping with all that, it also has to perform special functions in a crash. We have multiple air bags, who’s operation is tuned to the ‘type’ of crash detected, we have automatic engine cut, hazard indication, seatbelt pre-tensioning and some cars even ring for help. The structure is designed and tested to ensure it collapses in a controlled manner, the engine design is constrained by pedestrian head impact tests on the bonnet, even the steering wheel is designed to steadfastly hold its position as the cars structure a few feet in front of it is crushed at a rate of up to 15 meters per second.
Name me one other machine that has to detect, reliably, when it is about to be destroyed and then deploy safety mechanisms in a controlled and measured manner during the actual process of its own destruction. You’ll struggle with that one.
Now this feat of engineering would be amazing even with an unlimited budget, but the fact is that cars are made as cheaply as possible, which just take the achievement from amazing to utterly astonishing. In fact you can buy a basic car for the price of a really good telly, that’s bonkers.
Please take a few moments to look at your own car, and marvel. And if one part goes wrong by all means take it back and get it fixed, but do try to be sympathetic to the scale of the problem engineers face.
I noticed something interesting during the Toyota recall, the media could have played a very useful role and helped society, I say ‘could have’ because what they actually did was the complete opposite.
What they could have done is reported actual news, facts presented objectively such as ‘a small numbers of cars may have a fault causing the pedal to be stiff’. That is a fact, it gets the info over simply and effectively, you know what is being said. Simple.
They could have gone further and said something like ‘if your pedal feels stiff visit your dealer, but first check the floor mat hasn’t got stuck under the pedal’. That would be helpful.
But they didn’t do that.
No, what actually got reported was along the lines of ‘mum of five in death plunge tragedy’ and ‘is your car a ticking time bomb of doom?’. Stupid, dramatised gossip that conveys absolutely no useful information.
But of course this scaremongering helps to boost sales of that form of media bilge, so expect more useless crap in the future about every important storey going.
And this is a real problem, not only because it leaves us all badly informed and scared, but because the car companies now know that being honest and open has become the wrong thing to do.
All media has a responsibility, and its time they (we) faced up to it.