Diagnostics

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.

My HTC running Torque, this window lets me set up a virtual dash showing any info I want from the car
My HTC running Torque, this window lets me set up a virtual dash showing any info I want from the car

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.
The Blootooth OBD interface similar size to my phone.
The Blootooth OBD interface similar size to my phone.

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.

The usual place for the OBD connector on any car is under the dash near the steering column.
The usual place for the OBD connector on any car is under the dash near the steering column.

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! 😉

Sterling Engines

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.

I like this design, purely because it's weird!

 

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.

Running cars on water

Can you run your car on water?

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.

Can you run your car on water? Well, not like this, obviousely.

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.

The difference in power at part load by introducing a sniff of Hydrogen.

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.

First attempt, stainless steel wire in plastic formers.

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.

Second attempt after a few thousand miles. Third version ran cleaner.

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.

First instalation, about to test current and voltage on my long suffering Land Rover, subject of a great many experiments...


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.

Research.

Don’t just take my word for it; here are some of the research papers I used in my research:

SAE 841399 1984

Water/fuel mixtures

SAE 740187 1974

Lean burn with Hydrogen supplementation

General Motors Corp.

SAE 810921 1981

Lean burn with Hydrogen supplementation

University of Michigan

SAE 2004-01-1270

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.

The genesis of the Jaguar V8

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

Potent as the V12 was, it weighs about 350kg on its own! As I found out when I built this XJ-S...

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.

The Jaguar V8 would also make a damn fine race engine...

 

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.

The new XK was launched with the revised 4.2 V8, a swansong for the first generation V8.

 

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.

Land Rover with Jaguar V8 power, a rather good combination in my opinion.

 

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.

From E Type to XJ supercharged 5.0 V8, innovation lives on.

 

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.

An experimental race vehicle recieves the new 5.0, light and strong with a tuning potential well above 600bhp.

 

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.

Fault codes and conspiracy

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

The check engine light, lack of knowledge can lead to bad interpretation and expense.

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.

Be careful what you put in the tank, cheap fuel can cause expensive repairs.

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!

Manufactureres spen millions testing engines in all conditions to eradicate faults.

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.

Its complicated enough without conspiracy theories.

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!

The Mugen Honda Civic Type R

The Mugen Honda Civic Type R has a very long name, it also has a very big rear spoiler which is attached to a very small car. Small cars with powerful engines are a tried and tested recipe for fun, thrills and teenagers driving into lampposts outside McDonald’s, in short it’s a winning formula so it seemed rude not to take up the offer of thrashing this icon of the Burberry clad yoof of the day. The location for said thrashing was the fantastically twisting snake of a road that is Millbrook’s Alpine route, yes that’s the one where they filmed James Bond rolling an Aston but as I am not being chased by super-villains I feel confident that the car will remain shiny side up. And that is quite important as there are only 20 of these UK models, although as always with ‘limited editions’ if popular there will surely be further runs of similar but not quite exactly the same models. Right, enough preamble, to the car:

More badges than a keen Scout.

Snug is a good word, even the word ‘snug’ feels snug, as do the Mugen’s seats. The interior is a bit like a condensed version of that corner of Halfords where all the hoodies gawp at excessively loud stereos, as well as the usual dash with the now obligatory ‘Start’ button there is an extra set of largely pointless gauges telling the driver things that most wont really understand in a sculpted pod. When I used to write for Max Power magazine I would see a lot of this sort of thing. But whilst it is very easy to mock, the remarkable thing is I rather like it, it appeals to the child within in much the same way that those enormous Lego Technic sets do, I feel that at my age I really shouldn’t but actually I really want to. As soon as the seat hugs me and I pull the red seatbelt down the whole car just screams to me ‘drive fast’, so not wishing to disappoint that’s what I proceed to do.
The superb two litre VTEC engine is quite audible but still reasonably civilised, it pulls away without drama and can be driven normally, although I have no idea why you would want to because as soon as it comes on cam at about 5500rpm there is a goodly surge of thrust and the engine starts screaming like an aged rock star on a come back tour; strong, purposeful, loud, tuneful with a rough edge, exciting even, but not necessarily something you would want to listen to at 6am on a damp Tuesday morning commute.
In low gears the 8600rpm rev limit arrives rapidly and a certain joy is to be had swiftly charging through each of the close ratio gears, the selector is wonderfully accurate and fast (I believe the trendy term is ‘snickerty’ or something, but that sounds like a word made up by people who cant describe things properly).
The exhaust noise is predominant but the intake makes a healthy roar too, when blasting through the gears the rasping and popping is terribly addictive urging me on to higher speeds just so I can change gear again. I actually found myself laughing out laud.

The Civic is a futuristic looking car anyway, maybe it should fly?

Turning into fast corners in the standard Civic results in the now traditional dull under-steer and a vagueness to the steering, the Mugen is a world apart and very direct, a lot of the compliance has been taken out and the geometry altered to suit the sportier driver with remarkable results. The turn in is so positive that I feel I could just will the car to go round corners, it responds quickly to every input from me and almost becomes an extension of my body. I say almost as it is not quite the same as a true race car, but there again this is a road car that can still accept a full load of shopping, it’s still hugely addictive and I soon find myself deliberately taking tighter lines round corners just to enjoy the joy ride.
Each corner follows the same format; brake late enjoying the powerful and responsive brakes, short shift a couple of gears enjoying the bark from the exhaust on overrun, throw an arm full of steering in and power out with the engine screaming round to the rev limiter, slicing through the roller coaster Millbrook track. Admit it, you want a go now don’t you!
For the first few minuets this car brought me sheer joy, I was laughing out loud. But after a while the fact that I had to keep constantly changing gear became a tinsy bit tedious, and the fat tyres tram-lining on the rougher bits of road surface required constant correction which started to become tiring.
And that’s it in a nutshell; the Mugen is huge fun, briefly. Not an everyday car, unless you are extremely addicted to go-karts and are slightly hyper active, in which case constantly flailing your limbs about to get the best out of the car will second nature.

Whats in a name? About 237bhp, actually.

Would I buy one? Probably not. But would I borrow a mates one? Oh yes, as long as I could get back from the race track before he finds out what I’d done with it!

Spec:
Weight 1247kg
Performance 6.0sec 0-62mph, 150mph, 30mpg
Length/width/height in mm 4280/1795/1440
Price £38599
Engine 1998cc 16v 4-cyl, 237bhp @ 8300rpm, 157lb ft @ 6250rpm
Six-speed manual, front-wheel drive

Subtle, unobtrusive, both words that seem lost near that wing.

The most powerful piston engine in the world

Big is good, it’s official.
As you hopefully know, power is generated in our car engines by burning fuel. The heat makes the pressure go up which pushes the piston down just like you foot bearing down on a bicycle pedal. It’s a nice simple theory. The trouble is that most of the heat released into the cylinder is wasted, at full throttle about a third goes into the coolant and the other third goes down the exhaust pipe. At part throttle its even worse, up to 90% of the heat is wasted. A small fraction of the exhaust energy can be recovered with a turbo but basically it’s very wasteful.
So how can we improve things? Well, to retain more of the heat energy in the exhaust we can reduce engine speed, allowing longer for the heat to be used. But how can we reduce the heat absorbed by the cylinder wall? We could use some funky materials like ceramic but that has its own problems.

An engine, look carefully in the middle there is a bloke on the third floor! (Picture - WÄRTSILÄ)

However, one fundamental scaling rule applies to all things in the universe, if you double the volume of something, the surface area only increases by about 1.4. This is good for engines because a smaller proportion of the heat is lost to the cylinder walls. It’s not so good for creatures that breathe through their skin, like spiders which can never get much bigger than your hand without collapsing in a heap.
So why not use massive engines everywhere? Of course the efficiency bonus of big engines only applies at high loads, at part throttle the massive cooling effect of a high surface area ruins the fuel economy, so in the car world we size an engine to be appropriate for the job the car is supposed to do. For instance, when cruising down the motorway most cars only need about 18 bhp, so building a small engine that has peak efficiency at that power would be great for that single job, and indeed that is what the ‘mileage marathon’ cars do, but of course there is nothing left in reserve for accelerating, so we go for something closer to a 100bhp engine in a smallish car.
But what about something bigger? The biggest vehicles produced are ships, and in particular supertankers which can be the length of a drag race track.
So the subject our adoration is the mighty Wärtsilä-Sulzer RT-flex96-C, in particular the 14 cylinder version. Its total cylinder capacity is 25480 litres, I’ll just let that sink in for a moment.
It is a two stroke diesel engine with four, very large, turbos and computer controlled poppet type exhaust valves. It gobs out 84.4Mw which is 114800 bhp at only 102 rpm, and as you probably know torque is power divided by speed, that equates to about 6 million lb/ft of torque. Which is a lot.
Fuel economy is brilliant at full load – amazingly only 171 grams of fuel per kWh, ok that might not mean too much to most people but it is about twice as good as a diesel car. But if you drop the load to 85% and best efficiency the consumption is only 163g/kWh, which with the fuel containing 42.7 Mj/kg relates to about 51.7% efficiency. But this is not the best efficiency in the piston world, I think that is the Man S80ME-C7, catchy names.
Now that's a big crank, you should see the ballencing machine! (Picture - WÄRTSILÄ)

Everything about it is big in a whole new way; each cylinder is 960mm (37.8 inches) bore by 2500mm (98.4 inches) stroke, giving 1820 litres per pot. At full tilt, 102 rpm that is, a mean piston speed of 8.5 meters per second and the average pressure in the cylinder (MEP) is about 20 times higher than atmospheric which all means that each individual cylinder produces over 7700 bhp (the same as a top fuel drag race car) whilst consuming about 160 grams of heavy smelly fuel oil each stroke.
The outside is even more impressive, they call this type of thing a ‘cathedral engine’. At nearly 14 metres tall, 28 metres long it has four stories of walk ways round it. And weighing in at 2300 tonnes its not going to fit in a car!
Even the fuel pump is impressive, it looks like a huge V8 designed by Dr Frankenstein and delivers up to 1660 gallons per hour of heated fuel oil at 1000 bar to the common rail diesel injection system. Each cylinder has three injectors which are operated independently to control the combustion flow, the way the flame moves around the chamber, resulting in no smoke even at full load. The fuel control allows the engine to run over a wider range of speeds than older generation engines, indeed on the 12 cylinder version they managed to get it to run at only 7 rpm experimentally, that’s one ‘kaboom’ every 9 seconds, which is very slow.
It uses, more or less, the usual two stroke block scavenge intake system, that’s where the underside of the piston compresses the air. But that’s as far as normality goes, here it is refined with one way valves the size of tea trays and then the air hits four very impressive turbos, each the size of a small garden shed, before going through inter-coolers the size of Portacabins and entering the cylinder via a port near its lower edge. For starting, massive electric blowers pump in air at about 30 bar.
The exhaust poppet valves are fully computer controlled, a servo uses oil at 200 bar to move the valve up and down, so the cam profile exists only as software in the virtual world of the control box and is totally variable. The exhaust valve opening is reduced at part load to keep the exhaust temperature above 150 ºC to prevent tons of sulphur from the unrefined fuel corroding the exhaust after treatment system.
The pistons are mounted solidly onto an upper con rod, called a piston rod, that has a joint at the bottom that runs in guide rails, to keep the piston rod upright all the time. It’s called a cross head and ensures that the piston has no side loading and the oil control is tight enough to give the engine a 30 year service life, and most of the time in all those years the engine will be running flat out, which is pretty amazing. The lower end of this rod connects to the con rod proper and then on to the crank, the main bearing caps have ladders on them for the service crew to walk up.
Did I mention it’s quite big?
These engines are used in container ships like the Emma Maersk, about 170 thousand tons of it which is propelled at up to 26knots and is assisted by no less than five 8000 bhp Caterpillar engines just for helping with manoeuvring.
It’s got quite a big propeller too.