The Mystery of Mr Yunick

Mystery is a funny old thing; life is generally richer for it but when it comes to engineering, a mystery is like having worms, it constantly gnaws away in a really irritating way. So, dear reader, I am going to give you worms.
As you may know, a traditional car engine struggles to turn 30% of the fuel’s energy into useful power, although bigger engines are better in this respect and the largest piston engines can reach up to 50% efficiency.
There have been many attempts to make a better engine, but not content with these options, a legendary NASCAR mechanic and top racer Henry ‘Smokey’ Yunick started thinking about the main losses – coolant and exhaust heat – and how that energy could be re-routed back into producing useful power. And as he was a very practical kind of chap, having also invented a silent tyre, extended tip spark plugs and reverse flow cooling, he not only devised a theory but set about building some working engines, based on bog-standard road cars.
After building a number of amazing engines, one of which was used regularly by his daughter as a daily driver (see correction below!) , he also set about patenting the system all over the world. Once he had the relevant protection for his idea he was going to show the world.
Unfortunately, and rather frustratingly for the world in general, he then died. His company and family are still pursuing world wide patents on the various clever bits that make it work and are reluctant to let anyone else play with his creations.

(Please see the fantastic reply from his daughter below for corrections!)

His patent applications make interesting reading, and generate as many questions as answers. What he describes is a way of recovering almost half of the waste heat from a standard car engine, some of his conversions are claimed to double the car’s acceleration and its mpg at the same time. His daughters VW Golf is said to produce 150bhp (up from 110 as standard) and average over 60 mpg (up from 30mpg).
One of the problems with using petrol in an engine is that it tends to form clumps of molecules which can only burn on the surface, leading to un-burnt fuel and partially burnt fuel being thrown away down the exhaust pipe, these are the hydrocarbons (HC) you see on the mot test results.
Interestingly Smokey’s design uses carburettors, the heat is used to evaporate the fuel giving a more homogeneous mixture which burns more completely. This is a technique used even today by the car industry on injection systems, at part load fuel is injected onto the back of a closed intake valve to use the heat.
Heat is the key to Smokey’s design – in simple terms it first uses the coolant to heat the air fuel mixture to 90ºC at which point the fuel is almost entirely gaseous. It then uses the exhaust, which completely surrounds the intake, to increases the charge temperature to 230ºC. At this point the mixture has expanded quite a bit so a turbo or ‘Homogeniser’ as they call it (not a turbo in the traditional sense because it further heats and mixes the fuel with air) blows down the manifold to stop the mixture escaping back up the intake. The heat will have increased the charge pressure quite considerably, thus turning more heat energy into pressure energy that the engine can convert into torque. And the turbo, sorry – homogeniser, will have boosted things a bit further too, but of course the density will be quite low unless the turbo is running very high boost, and there is no intercooler to waste heat energy. With very high intake pressure it is also possible to re-design intake cam duration to get more cylinder filling, although it is not clear if this is part of his design.
Now the piston compresses the mixture which heats it up further to 820ºC. Now normally this would have detonated and blown the engine to bits, petrol mixture goes bang at about 350ºC, so clearly Mr Yunick was doing something very clever here and the info he had released may be deliberately misleading to buy him time whilst he got the patents, but what ever he did there it is his main secret and you will no doubt be very disappointed to hear that I have absolutely no idea how he does this. Clearly the nicely mixed charge is not really at 820ºC if combustion is going to start with a spark in the conventional manner, although enough energy has been put into it to reach this temperature. If combustion starts in a diesel type compression ignition then the whole charge will go bang at once, rather than a diesel’s controlled gradual burn, and blow the piston. Something must control the combustion?
Could it be water injection? Water mist would reduce the mixture temperature and itself expand in the fierce heat and generate more pressure and thus power. But that’s just a guess on my part and no mention of any other substance exists on the patents.
On the cars he converted there is a very small radiator and no fan, allegedly coolant volume is very small too, helping warm up time. These cars have been driven by a number of journalists and the performance and fuel economy have been verified, so in that respect the design has been ‘shown’ to work.
The only clue comes from some of the mechanics that worked for him who have alleged that the engines were very prone to pinking and melted pistons, but to be fair so do many ordinary mass production engines when they are in their prototype stage.
It’s a strange situation, undoubtedly Smokey was a great mechanic and built some of the best race cars in the world, so he was no amateur and knew what he was doing. Some people have wondered if it was an elaborate hoax to poke fun at the establishment, but why would you fund world wide patents for a hoax and what about the cars’ performance? And why are his ‘prototypes’ still in use? Why won’t the family let anyone else take the engines apart? So many questions.
It’s interesting to note that these revolutionary high efficiency engines are still only using 60-70% of the fuel’s energy, so it’s not in the league of infeasible perpetual motion machines, the energy balance makes sense. It’s just the combustion control that makes no sense and is without any explanation. These ‘Hot Vapour’ engines, if they turn out to be real, have amazing abilities and could herald a new era for piston engines. Just imagine a 600bhp V8 that does 60 mpg. It’s a beautiful idea.

Wombles

There are some deluded factions of the motoring press that have loudly and ignorantly derided a very useful and miss-understood service that helps motorists in need and saves police time.

The motorway Traffic Officers are referred to by one loud mouthed buffoon as ‘wombles’, but they answer a long standing complaint made by hoards of motorists since the early days of motorways; why are police used to do non-police type work such as directing traffic round a crash site, staying with crash victims until help arrives, sweeping up debris off the motorway, putting out emergency signs and cones etc. The list goes on, there are a huge number of time consuming jobs that although important don’t really need an officer with the powers of arrest and a highly equipped patrol car.

For years drivers argued, mostly in pubs, that it would be far better to have someone else to do these tasks and free up the police to chase criminals. And that is exactly what the Traffic Officers were invented for, yes my friends this is a case of the government actually listening to the motoring public.

And it works too; a friend of mine was involved in an unfortunate incident when they managed to spin on a motorway slip road and ended up bouncing off both crash barriers before coming to a halt at 90 degrees to lane 1. Which is bad. The Traffic Officers arrived and immediately coned off the lane whist they pushed the wreck to a safe position, then after assessing the situation for safety they cleared up the debris and re-opened the lane very swiftly. The police arrived and took details, did a breath test and the usual checks but then were immediately free to move on to the next drama, meanwhile the TO stayed with my chum until the recovery truck arrived. They also notified the roads agency that the barrier needed mending. All in all a very efficient, helpful and potentially life saving service. What’s not to like?

Sometimes where people have been hurt they have to close the road to recover and record all the evidence which can seem like an unnecessary delay to the uninformed driver, and sometimes being better to be safe than sorry means that some delays do turn out to be unnecessary, but I for one would far rather they were reasonably cautious than risk my life.

Every time I see a TO parked up apparently doing nothing I breathe a sigh of relief that this indicates that this particular stretch of road has no problems, no one has crashed, no one is having an utterly miserable day, no one is dying, it’s damn good to see a dormant patrol car. And when I slowly crawl through a conned off incident I give a cheery waive to the TO directing the traffic and restoring order to the chaos behind them.

So why are they being lambasted in certain media circles? Probably due to a fine and heady mixture of making up a good storey, being controversial to sell more copy but mostly pig ignorance and stupidity. Just the usual then.

Brakes explained

Racers claim that better brakes make faster lap times, but how can something that slows you down make you faster?

Simple; the better the brakes the longer you can stay on the power before braking for the next corner.

Brakes are all about heat, and ditching as much of it as quickly as possible, they work by converting the cars speed energy into heat energy which is then taken swiftly away in the air streaming through them, in theory. But a big car at high speed has an awful lot of energy; for instance getting a Bugatti Veyron to do an emergency stop from high speed might put the equivalent of several thousand bhp through the brakes make the discs glow bright red.

There are two basic types of brake, drum brakes get their name from the drum of steel with curved shoes inside that are pushed outwards against the inside of the drum when the brake pedal is pushed. These can be found on the back axles of cheaper cars and are quite frankly a bit pants; the braking force is limited, the pistons are small and the pressure pushing the shoes out into the drum is similarly small.

By comparison disc brakes can exert a much higher force onto the disc without risk of it failing.

It uses a disc with a set of pads held in a calliper that are forced against both sides of the disc when the pedal is pressed, generating much more force.

In both cases the disc or drum part is attached to the wheel hub so it rotates with the wheel and the pads or shoes are held stationary on the axle, or strut, or what ever dangly bits are attached to the suspension.
All brakes work by friction, pressing a pretty darn tough pad of friction material against the spinning metal, the harder the friction material is pressed against the metal the more friction is produced and the greater the braking force.
Brake systems use a special type of hydraulic oil to drive the pistons which push the friction material into the disc or drum. At the pedal end there is another piston in the master cylinder which is connected by hydraulic brake pipe to the slave cylinders at each wheel. In some cars the brake force is artificially increased by a servo directly connected between the brake pedal and the master cylinder, this uses vacuum from the intake manifold to move a large diaphragm when the brake pedal was pressed, as the pedal moved down small holes in the servo control section are progressively uncovered which applies more vacuum to the diaphragm which in turn applies a greater force to the master piston of up to four times the force at the pedal.

Some cars with Anti-lock Brake Systems (ABS) use a powerful electric pump to do this instead. The ABS system measures wheel speeds and if it detects that a wheel is slowing down faster than a safe limit then it knows that that wheel is about to start locking up, so it lets the brake pressure off the individual wheel by opening a solenoid valve in the ABS valve block, just for a tiny fraction of a second until the wheel frees up just enough to know it wont lock. You can feel this when it happens as a sort of buzzing or vibration under the brake pedal. ABS allows maximum braking force without the risk of skidding. But if you are going to fast then you are still going to crash no matter what the brakes do.
The fierce heat generated from heavy braking has to be dissipated into the air which is why race cars have ducts taking fresh air from the front of the car to the disc centre, the hot air then has to go somewhere and the design of the wheel should allow it to escape readily. To get more heat into the air some discs are vented with radial channels cast into the disc to draw air from the centre outwards, some discs also have small holes drilled through for even more ventilation but these can lead to cracks starting unless they are made very well. Groves on performance discs can help remove the tiny gas layer that build up between the pad and disc sometimes and increase pad bite, the down side is that they can increase pad wear when used aggressively.
The brake size needed on a car depends on its weight and how fast it is likely to go, more powerful cars can more readily get up to higher speeds they need bigger brakes. Bigger pistons and a larger diameter disc make better brakes. Also if the brakes are going to be used for long durations, such as when racing, there is less time between brake applications for them to cool down adequately, this is where vented disks can be a real benefit.
All that heat soaks through the system into the brake fluid and although it is engineered to work at these very high temperatures in extreme cases the temperature can get high enough for the oil to boil, this generates gasses which compress easily and make the brake pedal feel very soft. This is brake fade and in really bad cases the brake pedal can sink to the floor with very little braking force generated, pumping the pedal up and down a few times can sometimes help but basically if the brakes fade on a race track then the car generally crashes. That is why on roads with long descents the car’s speed should be controlled by using a low gear and engine braking rather than holding the brakes on for extended periods.

Old brake fluid absorbs water which boils and fades much more easily which is why it must be changed every few years to stay safe. Silicon based fluid is different and doesn’t absorb water but moisture still pools inside the system and needs flushing through every few years, it’s also a bit more squashy than mineral fluid making it unsuitable for fast acting ABS.

Brakes are often overlooked and any wear only becomes apparent at the mot or in an emergency stop. The trouble is that they have a hard life and can disintegrate with the friction material splitting off the steel backing or wearing down to nothing unnoticed, and they usually seem to work fine right up to the point were they don’t work at all and you crash. Maintenance and regular inspection is vital.

Setting suspension geometry using string.

It’s well known that suspension alignment is crucial for handling and safety, but how much can be checked at home? The main one that we can usually adjust is the front toe angle, but even though there might not be a simple adjustment for rear toe, camber, castor etc. it is worth checking them soon after buying a vehicle, just to see if it is straight.

What’s needed is some sort of datum point from which to take measurements to the wheels. The simplest way of doing this is to use two pieces of string, the thinner the better, one each side of the car at hub height and parallel to each other. With the car sat centrally between them we can measure from the string to the front and rear edges of each wheel and find out at what angle they are pointing in or out.

This method takes practice and initially may take time to set up and get consistent results, especially when you mess thing s up by tripping over the string. But with perseverance it becomes a very quick and surprisingly accurate operation.

ACCURACY VS PRECISION

It’s very easy to spend ages taking detailed readings, but beware. It’s easy to have accidentally moved the string, thus highlighting the difference between accuracy and precision. For example if you measure a block of metal that is in fact 50mm wide with a cheap digital vernier that reads 47.9836mm, it is very precise but not very accurate. By contrast if you use an old tape measure it may read 5cm, not very precise but completely accurate.

With the string method we are looking for accuracy, and consistent results.

Park the car on flat and even ground, this is very important; you can’t do it on grass.

Attach a piece of string to a suitable stand that won’t move when you pull the string tight, such as a breezeblock, at each end. The string must be at the same height, give or take a couple of millimetres, as the wheel hub centres and extend beyond each end of the car by a foot or so. The string should be as close to the car as possible without snagging on any bodywork etc. Ideally we would get this parallel to the centre line of the car, but as that can be difficult to define, just make it parallel to the sills to start with. It can be adjusted in a moment. Next put the other string on the other side in the same manner.

Now measure the distance between the strings at the front and the rear of the car to check they are parallel and adjust the string stands evenly until the same measurement is achieved at both ends.

Bear in mind that most cars have different track widths front and rear, so don’t expect the same hub to string distance front and rear.

When taking a measurement hold the ruler just underneath the string and take a reading from the edge of the string closest the car. With practice, and fine string, it is quite possible to get precision to 0.5mm, more than enough for our purposes.

You should now have two parallel lines at hub height, so to measure toe angle you can measure at a right angle from the string to the front and rear edges of the wheel or tyre, but beware, there are pitfalls here. Toe angle is very rarely quoted as an angle, that would be far too simple, so instead we work with a measurement which is the difference in the distances between the front and rear edges of the wheel/tyre. Now, to make it more complicated there are three systems in use, usual European method is to measure to the edge of the wheel rim (which is often bent and suffering kerb damage making the measurement difficult), the Japanese method is to use the step before the rim (more sensible as less prone to damage but depends on wheel design as how easy it is to get ruler on), the Americans go for the mid point of the tyre side wall (how you judge where the middle is can be tricky). So it is important to check the manufacturers’ specification before measuring your car.

Now, as we won’t be measuring between the wheels, but instead from the string to the wheel, we are effectively looking at half the car. So what we need to do is combine the reading from both sides.

For example on the car pictured here, the measurements from the string to the front left wheel are 47mm at the front of the wheel rim and 46mm at the rear edge. So the front edge is 1mm further inboard than the rear.

Now onto the right front wheel and I have 51mm at the front edge and 49mm at the back. So it is 2mm inboard at the front.

That means that I have a total 3mm toe in. And the car is slightly closer to the string on the left and I also haven’t got the steering set quite as straight as I thought, but the latter doesn’t affect the results.

Measurements at the rear are 47mm on the left and 50mm on the right. In both cases it is the same at the front and rear edges. So the rear wheels are completely parallel.

All this makes the assumption that the wheels are not bent or dented, so it is useful to check the run out first.

Jack and properly support the axle up until the tyre is just off the ground, then place a suitable datum, a breeze block perhaps, next to the wheel and clamp a ruler onto it so that its edge is just touching the wheel rim. Next, spin the wheel and see if the gap opens up or the ruler gets pushed back, anything more than a fraction of a mm is less than ideal, although its amazing how much wobbly wheel factor some people live with. If the wheel is bent then it is still possible to check the geometry, but the wheel has to be set so that the front and rear edges where we take measurements from have the same offset, but its obviously best to get it fixed first.

Another potential problem is that as the car moves forward or backwards, the suspension moves on the bushes. This means that you get a different toe angle reading depending on whether you reversed the car or went in forwards before measuring it. The best bet is to take a set of measurements then drive the car in the other direction for a few feet and take another set. This usefully highlights any potential bush or bearing troubles too.

Normally it’s the readings taken when the car has moved forward that are more important, after all that’s the direction you normally drive in, but the driven axle has to cope with being pushed forward when accelerating and being pushed backwards when braking. So both readings must be within specification.

Next up we can check to see if the front and rear axles are centred properly. The first step is to check the wheelbase on both sides and compare this to the manufacturers’ specification, bearing in mind that some cars, such as the Renault 4, have a different wheelbase on each side.

Having set the strings up to be parallel measure to the hub centres, and also to suitable datum points on the body/chassis such as the seam on the sill. If the car has been badly repaired after a shunt then one axle could be offset causing the car to crab. Should the results show the car is out of alignment, it might be a case of rebuilding the suspension or possibly the body may need straightening. However, before embarking on any drastic action based on the string and bricks method its worth double-checking at a professional alignment facility.

The next step is to use another piece of string and a bolt to test camber, most cars have the tyre inboard of the wheel arch, or at least they should. So by attaching a simple plumb bob to the top centre of the wheel arch with some sticky tape we can measure from the string to the top and bottom edges of the wheel and see how far it leans in or out. Now, this is absolutely dependent on the car being on flat ground, so check the ground with a long sprit level first. Also the tyres need to be inflated correctly and be matched so the wheels on each side are the same height off the ground, check this by measuring from the ground to the wheel.

Now, camber measurements are usually quoted as angles, so we need to convert our mm measurements in to degrees. This involves a small amount of school trigonometry, what we have is a triangle; if the top measurement (O) was 31mm and the bottom one was 21mm then there is 10mm difference, if the top and bottom measuring points on the wheel are 300mm apart then the triangle has a long side (H) of 300mm and a short side of 1mm, so the camber angle (a) is the inverse sine of 10/300 = 1.9 degrees.

Checking your car’s steering and suspension geometry can be quite simple, once you get the hang of it, and although the accuracy isn’t as fine as with laser alignment kit it does give a very useful idea of which way your wheels are pointing, can help highlight suspension faults and it’s a technique that is used by some of the top motor racing teams to this day.

Practice this method until you become proficient and you’ll have a simple and easy to set up system ready for use almost anywhere.



I like RWD, but I also like FWD, but which is best?

Another great pub debate question, of course 4WD is the best solution, but some purists would call that cheating.

Technically its a very complex subject, not least because RWD or FWD is only a small part of the whole picture. Suspension geometry and weight distribution are critical, but also tyres have a dramatic effect, and a cunning change of rubber can change the car’s handling characteristics utterly.

Best traction is usually found when the most weight is bearing down on the driven wheels, favouring FWD or mid engine RWD, but of course the engine is usually less than 15% of a cars weight, and at speed the aerodynamics take over, so even that rule is not set in stone.

There are, of course, rules of thumb. Most dynamics engineers reckon that FWD works best for up to approximately 300 bhp, above that and the weight shift rearwards when accelerating favours RWD.

When accelerating out of corners, FWD will tend to accelerate the car in the direction the front wheels are pointing in, more or less, where as RWD will tend to accelerate the car along its centre line, which on a corner where the front wheels are pulling the front away from that line so the driving force pushes the back end out, so FWD cars can get on the power sooner. But as ever, either case can be engineered around.

Going fast down the road also depends to a surprisingly high degree on how well the car suits your driving style; if your car does exactly what you are expecting, under or over steering, then you will get the best from it. It’s that predictability and familiarity that allows you to place the car accurately and easily just where it needs to be. That’s why two team mate’s F1 cars from the same stable are often set up to handle very differently. Also visibility is important, if the corners apex is masked by a massive A pillar then you cant judge your position properly on your mountain road. Confidence is key.

This may go some way to explain why some people swear by one or other set up, there will always be die-hard RWD fans who just cant get to grips with FWD, and equally there are hoards of FWD evangelists who can’t understand why anyone would want a car that spins off the road when you accelerate round a corner.

Winter Driving

With all this travel chaos about you might be forgiven for thinking that driving in a British winter is simply impossible, not so.

There are two factors vital to safe driving on snowy or iced roads, the correct winter tyres and adequate driver skill. It is a sad reflection of our attitude to driving that for the majority of road users both of these factors are sadly lacking.

I have been arguing for decades that winter driving skills and skid training should be a compulsory element of the UK driving test, as it is in many other countries where similar conditions exist, I also strongly believe we should all retake our test every 5 years. But irrespective of any test conditions we should all do a refresher course every few years, I am fortunate that as part of my work I am frequently assessed and receive training, and even after a quarter century behind the wheel I am still learning. Most good driving schools offer refresher courses for experienced drivers, and many also offer specialist skid training, a sound investment in your own safety and that of other road users.

But all the skill in the world would be pointless if your car still has hard summer tyres on. Winter tyres use a different rubber compound that maintains better grip on cold, wet or icy roads, they also have a very different tread patter with many tiny groves to allow the tread to grip the rough surface of icy roads. If you have never tried them the difference is amazing, not only allowing you to pull away in slippery conditions but more importantly they dramatically reduce stopping distances and help maintain steering. In many countries using winter tyres at this time of year is compulsory, with very good reason. Some people use a spare set of wheels for their winter tyres and swap over when temperatures dip below 7C, but for normal driving good quality winter tyres can be used all year round saving all the fuss and bother. Winter tyres usually have a snow flake symbol on the side and the word ‘Winter’ just to make it clear what they are.

With these two steps, and driving slowly leaving plenty of stopping distance, you can enjoy winter motoring just as much as in the summer.

And if you don’t enjoy motoring then catch the bus and stop cluttering up our roads 😉

But the thing is that most people who drive have no interest in cars or driving, cars have become a necessity to the vast majority and are marketed as convenience goods, just like a microwave or dish washer. So they are not likely to read blogs like this or tweets from the AA, and to be fair most of the time they don’t need to.

I was watching cars struggling up a very slight incline to get out of a car park at a retail park recently, a BMW 3 series took several runs and needed the backed up traffic to reverse out of the way before managing to slither onto the road. This was quite entertaining, but the point is that although these cars were on summer tyres and the drivers hopeless, they all managed to get out eventually.

I suspect that as long as most people can get away with it, any calls for improved driving skills and winter tyres will fall on deaf ears.

The theory of cheap motorsport.

Motorsport at any level is hugely enthralling, but the costs are prohibitive for the vast majority of enthusiasts. There are, however, a few ways round this and it is possible to do a day’s competition for less than the cost of a full tank of fuel.

The fastest cars in drag racing accelerate from 0 to 100mph in 0.8 of a second, and exceed 330mph in ¼ of a mile, but they will spend 500 quid on fuel for each run, followed by replacing most of the 50 grand engine. By comparison The Slow Car Club take bangers usually costing less than 500 quid up the track at Santa Pod on Run What Ya Brung days, entry costs 35 quid for a whole day of driving flat out. It doesn’t matter how fast the car is because after the first few runs you start trying to beat your own personal best time, it is highly addictive and lots of fun.

If you have ever fancied rally driving but haven’t got a rally car and baulk at the £300 entry fee for even the smallest of events then drop down a few gears and look at Production Car Trials. As the name suggests the cars are standard and there are classes for different engine sizes and engine/drive configurations, 4x4s are banned. The set up is simple; take a muddy hill with a few obstacles, mark out a challenging twisty course and see how far you can drive a car up the track before getting stuck. About the only modification you can make to the car is dropping the tyre pressures. The tracks are divided into 10 sections and you get penalty points depending on how badly you do, if you manage to get all the way up then you have no penalties and its a clear run. The skill required is remarkable and it is easy to get utterly immersed in the task of coaxing your banger that extra few inches up the track, it’s just as addictive as high speed track racing and highly recommended.

Another variant on the rally theme is the 12 Car Event, this is a navigational event run on public roads so speeds are modest. A route is issued to the drivers at the start line and timekeepers are stationed at the end of each section, the skill is in the teamwork between the navigator and driver to ensure the best route is taken and speed optimised to make sure the car arrives at precisely the right time. It’s very competitive and requires self control as much as car control, going to fast is as bad as too slow.

You have probably seen some footage of cars being expertly drifted round a very tight course laid out with cones in a car park. This is Autotesting and is a measure of drivers skill against the clock whilst negotiating hairpin bends, reverse parking and tight slaloms. You’ll need good tyres to get the best out of the car but for road car classes that’s about the only thing you can change. Precision and pace are needed in bucket loads, you think you can handle a car – this will make you think again!

But if driving flat out round corners is high on your needs list then consider Hill Climb or Sprints, this is usually on race tracks and does require a race licence so the costs start mounting but it does mean you can drive at high speeds on real circuits. The idea is simple – to get fro the start line to the finish line as fast as possible and its wonderful to watch as there is often old F1 machinery operating in the upper classes. If you wonder what the difference is a Hill climb is up hill and a sprint is on the flat, more or less.

In fact there is a surprising wealth of cheap motorsport opportunities in this country, if you are handy with the spanners then there is Grass Track (sprint races in a field), Comp Safari (rallying for grown ups), economy runs (more fun than you might think) and even real circuit racing can be done on a budget of less than £3000.

Currently I am liking the idea of buying a bargain banger for less than £500 and seeing just how many events it can do in a year. Probably something old, maybe another Jag, or a 2CV, or a Maestro, the more un-motorsport the better, maybe a diesel. Anyone fancy joining in?

Rolls Royce Ghost



Cresting a tree lined hill in majestically controlled opulence, I marvel at the sheer volume of technical excellence dedicating its existence to making my drive a simply fabulous experience.

The Rolls Royce Ghost is unusual in RR history as it is expected that owners will drive it, for some of the time anyway. Traditional RR theory has it that owners always travel in the back and so driver aids were kept to a minimum, but the Ghost has a plethora of modern technological wonders to make driving easier and more pleasurable.

As with many cars today it has an electric handbrake. But it performs a more sophisticated role here than on a humble peasant hatchback, it holds the car at rest until the accelerator is pressed when it is seamlessly released, leaving the switch in this mode means that the brake is automatically applied when at rest and if the driver exits for a quick ‘comfort break’ in the hedges the gearbox is automatically put into parked too. This is surprisingly useful when swapping drivers on long trips and the such like.

Gear selection is elegantly simple with Park, Reverse, Neutral and Drive being the only options. It goes without saying that the system analyses your driving style and adapts to suit, almost anticipating your desire for a gear shift before you know it.

The head up display shows the current speed limit derived from the on-board camera and some very clever image recognition systems that look for road signs, this means it can pick up temporary and new speed limits which is something sat-nav based systems have no chance of dealing with. This is linked to the adaptive cruise control so you never need get caught for speeding ever again. The system also notices white lines and if it detects the driver drifting out of lane without indicating it will discretely vibrate the steering wheel.

But I found driving it a surprise for all the wrong reasons. For sure the power delivery is smooth and effortless, with a wealth of thrust available throughout the rev range, and the ride is supple yet responsive but a tad more twitchy than Roller’s of old. The cabin is well insulated from outside noise, shutting the door is like closing a granite lid on a padded tomb, but unfortunately there was a fair amount of road noise transmitted through the car itself, particularly tyre noise. This might be more noticeable because of the near total lack of other noise, yet having driven older offerings from this legendary brand where there was no noise at all at moderate speeds I do think this is genuine and a step in the wrong direction. Although it has to be said that with the Crewe built cars wind noise, scuttle shake and a tendency not to go in precisely the direction intended were always features, which have thankfully all been dispelled in the new models.

So if the new car is better insulated, more solidly built and has better suspension how come there is more road noise? Well, I think this may be due to the affliction that most modern cars suffer from; excessively low profile tyres.

The thing driving this move towards rubber bands is not solid engineering but the fickle whim of fashion. Even Range Rovers run on 40 profile tyres now, which is quite frankly ridiculous. Low profile means the tyre cant adapt to the road surface and makes for a harsh ride and a tendency to skitter on all but the smoothest of surfaces. Tyres are an important part of the suspension system and making them too stiff is like welding girders onto the springs. You’ll never see an F1 car on low profiles.

I would dearly love to drive this magnificent car on better tyres, then I am sure it would effortlessly waft in silent majesty, just as it should.

How to make an old Jag fast.

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.

 

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:

http://www.jagracing.co.uk/index.html

http://www.xjs6000.cc/

http://www.jag-lovers.org/

http://www.mig-welding.co.uk/

 



XJ220 – a hidden story



The chances are you have already heard about the ‘Saturday Club’, a band of enthusiastic engineers who designed the stunning Jaguar XJ220 in their own time just because they had a burning desire to make their dream into a reality. But what happened after the concept was unveiled and why did the V12 get dropped in favour of the Metro 6R4 engine?

The original spec had the Jaguar V12 powering a 4WD system, the engine would be based on the race versions which were doing rather well in GT cars such as the 7 litre XJR9. The V12 engine also saw life as the 6 litre 450bhp motivation in the XJR15 road car. In fact Jaguar made 6 litres the standard displacement for the V12 in the last XJS and the XJ12, which soldiered on under increasingly stringent emissions regs until 1997 (X305).

The XJ220 concept had a 6.2 litre variant which had been producing a reliable 550bhp+ on test, it had been run at full power for extended periods of time and performed well under all manner of arduous test conditions. But the Friday before the 1988 NEC motorshow début the over worked engine unexpectedly seized, with no time to fix it the show car that thousands ogled at that year (including myself) had to be pushed onto the stand. Not a lot of people know that.

The car was simply stunning and orders poured in. So the next step was to put it into series production and the job was given to TWR who already had strong links with Jaguar. At this point things started changing and customers start cancelling orders, partly due to the recession and partly due to the spec change.

The original concept was declared too heavy, but at 1560kg it was still a good 200kg lighter than the lowest spec XJS and stacks up well against modern supercars. Curiously the Jaguar V12 was declared unfit for emissions, even though it was managing perfectly well in the XJR15 road car and the 546bhp Lister storm, as well as in lower state of tune in the XJ12. The 6R4 engine owned by TWR had proved a reliable and powerful lump, not only powering Metro 6R4s but also some of the Jaguar GT racer cars such as the XJR10, and was modified to get it through emissions regs and slipped in place. Extensive development of the engine was conducted on public roads in secret by grafting the whole XJ220 back end with the engine, gearbox and suspension, into a normal looking Ford Transit van (Now owned by Goodwood). I am sure this change from Jaguar V12 to TWR V6 was in no way motivated by any financial advantage to TWR for using their own engine. TWR still have the service contract for these cars, with costs totalling many thousands each time, providing a useful revenue stream to this day.

But with this engine the production car failed to meet its 220mph ambition, 217mph was achieved only by removing the wing mirrors and other tweaks.

Traditionally the problem with turbo engines is keeping the intake air cool at full load, as the turbos compress the air it gets hot and can easily exceed 100C. Hot air is less dense and reduces power. In a race a turbo engine can work well, as the intercoolers have a chance to cool down every time the car brakes for a corner, but when testing maximum speed the engine is flat out constantly and the heat just builds and builds. This is where a naturally aspirated engine has an advantage, the V12 had been run regularly in competition at power levels above 600bhp, in fact the XJR12 race car managed 750bhp from its 7.4 litres. So surely this would have been a more logical choice for a high speed super car?

Then there is the matter of the 4wd system, this was a version of the Ferguson Formula as seen on the Jensen FF. Ferguson research was another company offering engineering services to the car and motorsport industries, in a similar way to TWR. Ferguson would later be bought out by the mighty Ricardo organisation in 1994, and Ricardo would later take on a lot of Jaguar engineering work. Whether TWR saw the Ferguson involvement as a threat is unknown, but dropping the FF 4wd system meant that TWR had sole control over the whole project. In engineering terms the 4wd system has many advantages and the weight penalty is relatively small, as proved by later Lamborghinis.

What ever the real reasons for the changes, the car’s weight dropped by about 200kg which helped in cornering but did nothing for it’s main selling point – top speed. It also made it a lot cheaper to make, which must have been a consideration.

With many orders cancelled and built cars selling significantly under their list price the project lost a little of it’s shine. Many cars are still locked away with delivery mileage only, and in 2007 two unused shells were discovered in Jaguar’s Browns Lane factory when it was being cleared for demolition.

I am sure the decisions made at the time were based on sound judgement, but I cant help but wonder what would have happened if they had stayed with the original concept. Certainly a 750bhp V12 and 4wd would have giving it something in the order of 250mph capability and made it faster in a straight line than a McLaren F1. Maybe in some alternative universe they did just that, and the magnificent Jaguar matched the dreams of the Saturday Club and is the legend that it deserves to be.