Andrew_marsh_ _dead_ends_and_u Turns The_automotive_bottom_drawer 1

Dead Ends And U-Turns: The Automotive Bottom Drawer

There are some ideas which reappear periodically that are either bad or awaiting some magic innovation to make them viable. You may not agree with what follows. THE GREAT OPPOSED…

Andrew_marsh_ _dead_ends_and_u Turns The_automotive_bottom_drawer 1

There are some ideas which reappear periodically that are either bad or awaiting some magic innovation to make them viable. You may not agree with what follows.


Armies love vehicles. They usually need engines with incredible power, that don’t need to work for too many hours, and may cost a fortune to build.

After the end of the Second World War there was intense competition to grab hold of as many innovative German ideas as possible. One idea was an engine with twice the number of pistons and crankshafts than the number of cylinders – the Junkers Jumo 205 two-stroke diesel aero engine.

As the army ‘high-ups’ said: “Now, gather round everyone and stick a pipe in your ear. See, here’s the cunning plan. Diesel engines burn anything, and we need engines that will burn anything, are super powerful and weigh nothing. Right? Questions? Off you go!”

In the early 1950s, army types laid down a series of contracts based on the Junkers Jumo 205 design and gave three contractors, Coventry Climax, Rolls-Royce, and Leyland, roughly 18 months to design and build prototype engines. Can you guess how this went? The Rolls-Royce version was the best.

Two of the three engines ended up on the Chieftain main battle tank. The smallest, built by Coventry Climax, produced a huge noise for such a small engine and was almost completely unreliable. The liners looked like they had been drawn up in thick crayon while blindfolded. When the engine could be bothered to work it provided auxiliary power, including for the electric turret. Oh dear.

The largest engine was built by Leyland, and like Coventry Climax, it dispensed with pesky details of the Juncker engines. As with the Coventry Climax engine, the liners had nominal cooling fins at one end and almost nothing at the other unlike the Junkers design (remembering this engine has one end of the liner running hot and the other slightly cooler). The crankcase was a bit floppy, so it was a bit leaky and the liners moved a bit, too.

The Chieftain tank was a magnificent device except for its engines. As many commanders knew, the moment the tank had to move, an ear-splitting noise and huge cloud of semi-burnt diesel signalled exactly where it was hiding. It was a bit like wearing bright red uniforms in the jungle.

“Now, again gather round and stick a pipe in your ear,” said the army ‘high-ups’ again. “Here’s the cunning plan. We hear there’s a German national living in Switzerland with a brilliant new ultra-compact engine.”


Felix Wankel was an inventor who developed air compressor technology, some of which is still in use today. He also had a few attempts at converting compressors into engines, and one of those used his name. A small German company decided to have a go, and the first engine for NSU had a rotor inside a housing, which was inside another housing. Dr Wankel had just about figured out how to get HT voltage to a spark plug rotating on a housing inside another housing, but had no idea about the rest.

NSU built the first engine, poured some petrol mixed with a little oil inside and somehow started it. The engine rolled around the workshop floor until the fuel was used.
The outer housing was removed, making the near perfect balance of the original idea imperfect. Mazda was an early adopter of the new engine type, and together with NSU, led the development of the engine, now with a single fixed outer housing. Others wanted to come in on this because the modular construction, better rotating balance, and very responsive nature were a step change from conventional internal combustion engines for regular road cars.

Disaster struck with the NSU Ro80, where owners would wave to each other to indicate how many new engines they had previously had fitted since the car was delivered. Citroen, always a bit edgy, sunk a huge amount of cash to build engines for itself and NSU, but found out too late that they were getting the B-level designs, and that the rotor seals simply did not work reliably. Oh, and add ‘alcoholic’ tendencies of the engine amid the 1973 OPEC oil supply crisis.

The initial fallout was for NSU to go bust. Volkswagen bought it for what became the K70, which in turn played its part in preventing Volkswagen from going bust. As for Citroen, thousands of scrap engines, hundreds of Birotor cars based on the GS with some CX bits (before the CX was launched) combined with the Maserati affair, led Michelin – the owners – to call time and allow Peugeot to buy the whole lot for little money. Within 18 months, Citroen was back in the black.

The Wankel engine carried on wrecking companies left right and centre, but Mazda turned it into a magnificent competition and road car engine before emissions finally stopped it rotating – for now. If only it had low-cost direct fuel injection.


Many years ago, Orbital Engine Company managed to produce a world-beating air-assisted direct fuel injection system that was not only less expensive than the traditional low- and high-pressure delivery pump systems, but also aided combustion with the additional air. A new vista opened up – stratified charge around the spark plug, the efficiency of placing a metered quantity of fuel directly into the combustion chamber, and more.

Orbital did not stop there. The air-assisted direct injection was part of a small, two-stroke petrol engine package, and for quite a while, manufacturers queued to buy licences and technology from Orbital. In Europe, Ford ran a small fleet of third-generation Fiestas with the engine.

A problem surfaced: the way the two-stroke engine was designed without an air pump required the fuel and lubricant to be ingested together via the crank case. To avoid poisoning the catalytic converter, the lubricant was almost pure base oil – yes, a total loss lubrication system. Only one licence holder avoided this issue by fitting a blower and that was Chrysler, which as usual, thought of something else and then ran out of cash.


Chrysler has had more than its fair share of stunning designs and absolute howlers. While everyone else was trying to get extra-pure hydrogen specially harvested from the peaks of the Alps to make the then-emerging fuel cell membrane technology live, Chrysler did a ‘hell no’. It developed a membrane for a fuel cell that was tolerant of diesel, knowing that the fuel cell stack would generate emissions and electricity, but those emissions would be reduced. Additionally, low-sulphur diesel is much easier to come by than hydrogen specially harvested from the peaks of the Alps.

The target? Truly awful, nasty little diesels used for refrigerated trucks. A diesel-powered fuel cell generates electricity directly, emits less and is almost silent. Then again, our wonderful renegade Chrysler thought about something else, and the idea didn’t go ahead with them.

Andrew_marsh_ _dead_ends_and_u Turns The_automotive_bottom_drawer 1
The Chieftain main battle tank.
Andrew_marsh_ _dead_ends_and_u Turns The_automotive_bottom_drawer 2
Felix Wankel.

Latest Stories

WordPress Ads