Top Gear Mitsubishi L200 Desert Warrior – Project Swarm

There wasn’t so much an actual ‘Design Brief’, more a sort of chat about really cool things to have on a car, and which were the best looking desert race cars ever. It was an unusual conversation from the start:

I need you to build a pick up, Dakar rally style with hints of Pre Runner, really massive tyres, and an aircraft wing on top.

A wing? For lift? Do you want it to fly?

No, it’s just to house the swarm of camera drones that need to be launched at the touch of a button.

Oh, right, that’s special. Anything else?

Yes, it needs an emergency survival moped fitting to the load bed. Oh and a winch, some jerry cans, on board tyre inflater, and lights, lots of lights.

An unconventional start to a design and build project certainly, but then again the customer was not exactly conventional either. Mr Tom Ford, known as Wookie for reasons lost in the mists of time (see early episodes of Fifth gear for clues), is and adventurer and ghetto engineer, apparently, with a genuine passion for great engineering and design. Usually he is fairly involved with his projects but in this case he was slightly inconvenienced by having to nip over to the USA to present Top Gear America.

Testing times. The L200 part way through build doing a shakedown run.

Most sensible engineers would say that this would take a lot longer than the three months we actually had to build it. But I’ve never really got on well with sensible so I leapt at the chance.

Clearly I needed the best team I could find, luckily I’ve worked with Dave Bridges and Brad Harrison before, awesome people who do amazing work (ask Dave about the V12 Studebaker) and who will stop at nothing to get the job done, add to this the legendary Paul Cowland helping by wrangling a whole host of suppliers and that gave me the confidence to take it on.

Everything is bespoke on this build, either built from scratch or using modified parts; the SuperPro suspension parts were for a slightly different model and had to be adapted. The roll cage was a custom build from Performance & Protection but with extra modifications for camera arms and all the other clobber we put in there. They are superb creators of roll cages and every time I asked for some

Some of the huge pile of new parts, steel tubing and electrics.

extra bits of high tensile tube bent in certain complex ways they met the challenge with grace and speed.

Mitsubishi UK were absolutely heroic during the build, their enthusiasm matched by practical assistance whenever called upon.

One thing that struck me as soon as I started working on the truck was how well the Mitsubishi L200 is put together, this is a working vehicle and everything does it’s job properly, robust, reliable and efficient. This made the project that bit more enjoyable to build.

The way I approached this was to start by making it look right, arranging the features in the best way for the filming work it had to do, then engineer it to get round all the hideous compromises that this gave it.

One thing became apparent very early on, there was a lot of weight going on it, but worse than that the weight was high up and a lot of it was behind the rear axle line, this is a bit of a nightmare from an engineering point of view as it makes it very unstable. The roll centre was high too, meaning that as you turn into a corner it takes time for the car to react, and when it does finally react there is a tendency for it to wallow, unload the wheels on the inside of the corner and loose traction.

With all that weight hanging over the back I needed to think of a way of making it handle, so my mind turned to what other cars also this fundamental design fault, so obviously the Porsche 911 sprung to mind. That particular miss balanced relic corners by putting most of the side force through the rear tyres and just using the front tyres to point the car in the right direction, or a close approximation of it. Really, when you analyse how a 911 suspension works, it’s prey similar to steering a wheel barrow backwards…. OK, I can hear the hate building now from the Porc fanciers, might have gone to far with that analogy.

Anyway, using that solution on the L200 meant loading up the rear tyres a lot more than the front, changing the front geometry, changing the drop ling angles on the roll bar and running the rear tyres at 50psi with the fronts set to just 35 psi.

To get some stability at speed I wanted to increase the front caster angle significantly, and as luck would have it the L200 has adjustable offset bolts on the wishbones, but due to the extreme nature of this truck even on its maximum adjustment I couldn’t quite get enough angle without the wheel fouling the wheel arch a full bump. Last thing I wanted was the tyres ripping the arches of when Wookie lands a massive jump of a dune, so further modification followed.

I also needed a rear anti-roll bar (standard L200 doesn’t have or need one) and a stiffer front roll bar. Now, stiffening roll bars actually reduces traction on normal roads as it reduces the wheels ability to react to road irregularities interdependently. Stiffer springs and dampers would be needed, but crucially I needed to increase grip by making the tyre contact patch bigger. Well, any excuse for bigger tyres.

The standard truck has tyres with a diameter of 28 inches, I tried a few ideas out, moving the suspension up and down and the steering side to side though its full movement to see how much space there was for bigger tyres, we could just about

Standard on the right, slightly non-standard on the left.

get away with 32 inch with a few adjustments, but that wasn’t really big enough for the look Tom wanted, with a bit more modification I could get 35 inch tyres in, this did involve cutting a chunk of bulkhead out, some foot well too, and welding it back together again in a slightly different shape. I also moved the washer bottle from the front left wheel arch to the rear right one and removed most of the ends of the plastic bumper.

The challenge with the wing was firstly where to put it. If it went on the roof it would look like one of those roof boxes that caravan owners seem to like, and I don’t think Wooky was going for the happy camper look. My preference was to hang it right out the back, like a Top Fuel drag racer, but then it would completely ruin the ability to get the emergency moped out in a hurry, which misses the point somewhat.

So that left the load bed area which is good for several reasons; firstly it looks good, secondly the air flow will be fairly turbulent in this area so the chances of the wing giving us unwanted lift are reduced. To be on the safe side I also angled the wing with its tail up a bit, so if anything it would give a small amount of downforce. Now, I expect you’re wondering why we didn’t just fit it upside down so it definitely gave downforce and not lift, well according to Wooky it’s something to do with aesthetics, meh. And anyway I didn’t want huge downforce there as the rear axle is already loaded heavily enough.

Stuart came down to the workshop to make some changes, he’s really good with rivets…

This wing has secrets. All is not as it seems. If you look at most aeroplanes you may notice the wings taper as they go out, so if we just cut a section of wing one side would be shorter than the other. A simple solution would be to cut the left and right wing ends off a scrap plane and join them together to make a symmetrical item, but that was not possible with this plane because one wing had been destroyed in the plane crash…

So the skills of Stuart (Stu-Art) were employed to take the wing section apart and let in new aluminium to even it up. Not an easy job, and one made more tricky by the need to fit a large compartment into the top of the wing so we could get the drones in.

After two week solid work, and a couple of all nighters, Stuart heroically set off from up north at the crack of dawn to bring the wing down to the Bedfordshire workshop. He even brought biscuits, top bloke.

Load bed taking shape.

Mounting the wing proved a tad tricky, the main spar which is the back bone of the wing runs diagonally, so the mountings had to be further forward on one side, this didn’t look great so we made wide mounting plates that allowed us to use the rear part on one side and the front part on the other.

I made a real effort to enhance the Mitsubishi styling, so the cut angles in the wings and around the front roll cage reflect the lines of the original front end, the mirror ally insert next to the headlights emphasises the width gain but also enhances the lines of the stock headlight, there’s a lot more detail in there than you might at first notice.

I knew I had to widen the wheel arches, but I didn’t want to just stick some plastic arch flares on, that would be far too easy. Thinking about Dakar rally cars and Pre Runner trucks I kept thinking about boxed out arches with big vents in. I also like the way the Mitsubishi design has angled lines joining with tight curves. Putting these two together was easier said than done, so one day I set the front right wing on the work bench and just cut it in two with a plasma cutter, using the existing Mitsubishi lines as a guide and reflecting the headlight cut out from the front. To be fair, at that stage it looked terrible, but I had a dream…

Fitting the remains of the rear edge of the wing back on the car, I then made some 40mm spacers to mount the rest of the wing. This created some interesting spaces and shapes, time to get creative.

Having mocked up a rough approximation of what I wanted on the wings I tasked Brad with making it work properly, creating a set of plastic and aluminium inserts and finishing it to a high standard. As luck would have it Brads dad runs a rapid prototyping firm which specialises in making tricky plastic thingys. Both of them worked long hours to create the extensions, they also added a bit of their own ides too which makes it a much more personal task.

Brad and me discussing arch angles, as you do.

Everything had to be designed so that it wouldn’t break if it was dropped from a great height or hit with rocks, which is pretty much what happened to it in the desert of Namibia

There are also a load of hidden modifications, I moved the intercooler up 5mm so I could make a better winch mount, it now has two batteries linked with a smart control system to run the winch and extra lights when the engine is idling or off. Lots of engineering detail that supports that stunning exterior.

This project has been an absolute hoot, I’ve loved it, sure there were a few sleepless nights but anything worth while does that. Here’s to the next mad project.


When you fit much bigger tyres the handling and steering is effected in many ways, the steering axis is inclined (king pin inclination) so the new wheels have a greater offset to compensate for the bigger tyres and keep the steering axis in the right place. They are 25mm further out than standard.

The lights, split charge, winch and drone flap are wired up with 360 meters of cable with over 70 connectors.

The second battery can be linked into the main battery at the press of a button to jump start itself.

The battery tray is from a 1989 Jaguar XJ12, it just so happens to fit the Mitsubishi rear wheel arch perfectly.

The on board air compressor can pump up all four tyres from flat on the charge from the auxiliary battery without being recharged.

The shop that sold the tractor exhaust flap also sells Unimogs and cat food.


Ground clearance increased (more than doubled) from 205 to 420mm

Approach angle improved from 30 to 42 degrees

Departure angle improved from 22 to 38 degrees

Ramp over angle improved from 24 to 28 degrees.

Tyres increased from 28” to 35” Reinforced off road tyres.

Track width extended 50 mm front and rear.

Full bespoke external roll cage, FIA race spec, main hoops use extra large 3” CDS high tensile steel tube.

Custom fabricated winch bumper with 9500lb pull high power winch with high tensile synthetic rope, full remote control.

High strength side steps / rock sliders made from 2” high tensile CDS steel tubing.

Modified wing of a Beagle Pup aeroplane mounted on custom aerofoil section tube frame, remote control flap releases camera drones from bespoke drone hangar.

Two ‘trawler arm’ camera mounts swing out from the sides for self filming using GoPro Hero cameras.

Two spare wheels on quick release rally style drop down cages, these incorporate rear view camera and auxiliary rear lights.

All terrain survival Motoped mounted in custom built integrated slide out ramp.

Two fuel cans colour matched to body paint.

14 main high intensity LED light units.

Six built in camera mounts

Two long range CB aerials

High lift jack and vehicle recovery system.

On board tyre inflater / air compressor.

Split charge system with additional heavy duty battery, automatic battery charge control.

Custom exhaust stack through load bed, high flow system.

Full race spec Cobra bucket seats with custom Mitsubishi logos.

High strength six point race harnesses. FIA race spec.

Special tool store for drone remote control, winch remote, compressed air line, survival tools etc.

Custom switch panel for lighting, drone hatch and battery charge control.

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.

Mighty Midget

The man and his dream machine

Stuart Gunn did something remarkable; he set about creating this remarkable car in a remarkable way.

He sat down and thought about it, worked through the options, made templates and jigs and then went about welding it all together in a sensible logical well engineered way. Which is remarkable when the very idea of a V8 4×4 Midget is so splendidly mad.

The basic concept was to take the drive train (gearbox, props, diffs and hubs) off a Sierra XR4x4, take a Rover V8 3.5 with a good road tune, add in the MG Midget and blend with a home made chassis and subtle body mods. The result is a beautiful looking car that is easy to drive and blisteringly quick, particularly off the line where the extra traction from the four wheel drive gives it one hell of an edge.

With the power to scare small children...

Stuart learned his craft over the years with a number of projects, which all started off a couple of decades ago as a yoof with a Morris Oxford with a jacked up rear, a flip front and side exhaust pipes. By trade Stuart is a panel beater, which shows in the skill with which the steel wheel arches are seamlessly blended in to the MG body.

looking down on creation...

The build started with his mildly tuned Midget that he had driven round for a year or two. He then measured everything up and made suitable jigs for the wishbones and chassis out of steel box, so that the final result would be spot on and match on both sides.

The chassis uses the best bits of the original MG tub, added to a box section lower chassis and tubular upper rails which hold the top wishbones and coil over dampers on.

The 4×4 system uses the Sierra front diff and so Stuart created his own unique front cross member with the diff mounting on the right hand side (on the Sierra it mounts onto the sump).

Wishbone jigs held the bush carriers in the correct place, then steel tube was cut and welded in place to join them together, that way Stuart knew the geometry would be as predicted and both sides match.

Cunning front suspension

The suspension uprights have the struts removed and a ball joint fitted in there place, these parts came from the kit car manufacturer, MK Engineering. Being a tad narrower than a Sierra, the drive shafts had to be shortened, but not by too much, only 70mm.

Springing comes from coil over AVOs all round, with adjustable spring seats and damping. The first iteration saw 150lb springs on the rear but these ended up coil bound, now it has 225s which are spot on. Damping was adjusted to give good ride quality and handling, but also to stops the mud flaps dragging when going over speed bumps.

Wing and arches hint at the potential within.

Stopping the car is taken care of by Sierra based disk brakes with EBC Green stuff pads. As yet there is no servo, this is one possible mod for the future, but for now the braking is still excellent as long as you press the pedal firmly.

When it came to fiddling with the engine, Stuart had a chat with Dave Ellis of DJE fame. Stuart is working on a tight budget and isn’t after stupid horse power figures so a package was assembled to give the 3.5 litre about 200bhp and great drivability. It has a pair of 4.6 heads which have bigger ports and valves than the old 3.5 units and are not too expensive, a DJE 210 cam for good road manners, a Webber 500 4 barrel carb and Rover electronic ignition coupled to an Accel Super Coil. The carb breathes through a filter with a cleaver mod, because of the lack of space the top of the filter housing is the bonnet, a flexible mounting lets the filter seat even when the engine twists under acceleration. Though fuel injection is on the cards for a future mod.

Relatively light weight but torquey V8

Stuart made his own exhaust manifolds from tube and then Custom Chrome Racing very kindly chromed them and made the rest of the system. Stuart has known CCR for many years and so was allowed to use their workshop to do the fiddly bits. In fact CCR even provided the steel for the chassis and wishbones as well as making the oil catch tank. The resulting exhaust has that wonderful V8 burble but is not intrusively loud, quite subtle in fact, in keeping with the theme of the car. And all with just one small CCR muffler on each side.

Various wheel arches were tried by Stuart, including ones off a Transit double axle, but in the end he again made his own which complement the understated look perfectly. To make these he took a piece of small steel tube and bent it round the tyre, then he flattened the tube and braced it to the body with more bits of tube. This made a perfectly formed skeleton which he could then make up some cardboard arch templates and offer them up until he got the look that he wanted. Once satisfied with the templates he made steel arches and welded them on to the skeleton. The result is well made and has a factory quality feel to it as well as looking the dogs danglies.

Smoothed front give nothing away

The body was finished off by removing the bumpers, fitting a natty small bumper at the rear, adding a boot wing, a small bonnet bulge and smothering the thing an a gorgeous Rover Caribbean Blue paint job.

When designing the car Stuart wanted it to be usable every day, and on a short trip round town the car proved that this goal has been well and truly achieved. The suspension soaks up the bumps well and copes with speed bumps effortlessly. Once out on the open road the thrust from the engine is never ending, pushing you into the seat and putting a grin on your face. The Toyo Proxes tyres grip well and corners are dealt with easily.

A wonderful car to drive in any conditions.

At low speeds the steering is a little heavy, using a power steering rack to get the 2.8 turns lock to lock, but as yet without the power steering bit fitted due to the lack of space in the engine bay. Electric PAS is a possibility. But as the speed builds it becomes lighter and very communicative.

A lot going on in a small place, front suspension may recieve PAS later.

All in all, this is a simply splendid car, well thought out and professionally built. Stuart has plenty of ideas for future tweaks but the basics are very well sorted out. The car would be marvellous at hillclimbes and sprints and Stuart is toying with the idea of doing a few competitions in the coming year, I for one would love to see it out there.

As a footnote, how different would history be if BL had put something like this into production back in 1972….

Stuart would like to thank the following:

Graham and Nigel at Custom Chrome.

Dave Ellis at DJE

Many friends, family and Midget And Sprite Club members for their support and encouragement.

Tech Spec:

MG Midget Mk3 1972.

Rover V8, 3.5l, lightened and balanced flywheel, Vitesse pistons, 4.6 heads, DJE 210 cam, Webber 500 4 barrel, Rover Lucas ignition and Accel coil. Approx 200bhp @ 5500rpm.

Owner fabricated 4-1 tube exhaust manifolds with Custom Chrome Racing system.

Owner fabricated spine type chassis.

Owner fabricated double wishbones all round. Fully adjustable.

Ford Sierra Xr4x4 gearbox (type 9), props, diffs, hubs, steering and brakes. Narrowed by 70mm each side.

EBC greenstuff pads.

Toyo 195/45-16 Proxes tyres on Ace alloys.

Avo coil over adjustable dampers with adjustable spring seats all round.

0-60 4.5 seconds ish.

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.