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OT: Diesel cars at Le Mans

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#1 SeaMonkey

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Posted 27 June 2003 - 01:26

I've hit a wall! I'm working on an article about alternative fuels in racing, and I'm trying to work out when the most recent appearance by a diesel-powered car at Le Mans might have been. There was the Delettrez car that appeared between 1949 and 1951, and the M.A.P. that ran in 1950, but as far as I can tell, there hasn't been anything since. Have I missed something glaring? Any help would be muchly appreciated.


#2 Ray Bell

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Posted 27 June 2003 - 01:40

Unlikely that either Peugeot or Mercedes-Benz would have run anything... and they've been the main proponents of the diesel engine through the period.

Le Mans was always a bit of a stickler for fuels too... maybe, except for the gas turbine efforts, alternative fuels weren't allowed?

#3 Wolf

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Posted 28 June 2003 - 16:30

If I may be so bold to throw monkey in a wrench, the main difference between Diesel and Otto engines (as we call them here) is not the fuel but what is entering the cylindres. With Otto engines mixture of fuel disperesed in air it the 'working medium' (rough translation, I do not know the correct term), whereas with Diesel engine it's the air (fuel is added during compression of 'working medium'. So, not directly in line with original inquiry, but when working under stationary conditions, Audi R8 might be considered Diesel engine that even 'clean swept' Le Mans (it has GDI, which in such condition injects fuel during compression, instead of during intake which is done when max power or torque are needed)...

#4 Frank S

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Posted 28 June 2003 - 18:53

You don't think this one might appear in a Le Mans car some day soon?

Really BIG diesel engine

Frank s

#5 Viss1

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Posted 28 June 2003 - 22:00

Originally posted by Frank S
Really BIG diesel engine

Very cool :up:

#6 Lotus23

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Posted 28 June 2003 - 23:02

There's no substitute for cubic inches, is there?

In the early sixties, I was an Army lieutenant stationed at a telecommunications facility in Saran, just outside Orleans, France. As the local civilian power was notoriously unreliable, our backup power source came into frequent use. It consisted of a generator powered by a large WWII surplus LST (Landing Ship, Tank) engine. That monster was several feet high and IIRC maxed out around 800 rpm.

The local "mechanicien" in charge of firing it up was very fond of his vin ordinaire and had a cot where he slept beside the engine. As Duty Officer at night, it was my job, whenever we lost power, to sprint the 25-30 yards out to the generator building and wake him up. Every time I performed this duty, I did as I'd been told and would yell "toot sweet!!" at him in my bastardized French. But he never moved one iota faster than he wanted to, and I eventually learned that my exhortations, though sincere, were counterproductive: it took him about 8 minutes with me yelling and about 6 minutes with me saying little.

That was one big engine, but it would've been hard-pressed to serve as a starter motor for the RBDE!

#7 D-Type

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Posted 28 June 2003 - 23:17

I think we have a cultural difference here.

My (British) understanding is a Diesel engine is one where ignition is caused by compression, as opposed to an electric spark

An Otto engine is any engine that has a 4-stroke cycle, namely
1 Ignition, or power stroke (downward)
2 Exhaust (upward)
3 Induction (downward)
4 Compression (upward)

Most diesel engines are 4-strokes.
Most petrol engines have carburettors to mix the fuel and air. Some, including all modern racing engines, use fuel injection. In some fuel injection systems the petrol is injected into the inlet tract, in others it is injected directly into the cylinders. I think the latter is what you are describing as also being a diesel

A 2-stroke engine (DKW, SAAB, Trabant, some motorcycles) is a valveless engine where the fuel/air mixture is introduced and the spent gases removed via a system of ports in the cylinder walls and in the piston. I have never really understood how it works but it is something like this
1 Ignition (at about top dead centre)
1(a) About halfway down the downstroke a port opens and the exhaust gases are expelled
1(b) At the same time the fuel/oil mixture is compressed in the space below the cylinder
2(a) As the engine passes bottom dead centre the partially compressed fuel/oil mixture is introduced into the space above the piston and displaces the last of the exhaust gases
2(b) About half way up the exhaust port is again covered and the mixture can then be fully compressed.
2© At about the same time another port opens allowing a fresh charge of fuel/air mixture to be sucked into the space under the piston.

Some Diesel engines are 2-strokes

Although inherently less efficient because it is impossible to remove the last of the exhaust gases, because of the lack of valves a 2-stroke can rev very high which offsets the inneficciency.

And to finally confuse things further, although a Wankel rotary engine has no reciprocating pistons it is a 4-stroke engine. I believe that NSU, Mazda, or someone has produced a Diesel (compression ignition) Wankel engine.

Phew! After thinking that hard on a Saturday I need a beer.

#8 Wolf

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Posted 29 June 2003 - 00:06

D-Type, You are to a certain extent right, but that's what I've been taught at my Uni. To complicate things even further there were some Diesel engines with 'rudimentary' sparkplugs (and quite a number of Diesel engines is equipped with heaters to assist ignition with cold engine)... And direct injection of gasoline can work just during intake (as it did on M196), or with variable injection timing (modern engines, as I've described for R8, with injecting fuel during intake cycle for performance, or into compressed air for lower fuel consumption)... There was neat little 2-stroke aircraft Diesel engine (Junkers Jumo, it was used in Junkers Ju86 bombers, IIRC) with two crankshafts and cyllinders 'working' against each other (engine had no cylinder heads). As for 2-stroke engines, most modern engines have either reed or planar rotary valves on either intake (most common) or exhaust port to prevent fresh mixture escaping from cyllinders.

#9 RTH

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Posted 04 October 2006 - 11:35

New Peugeot Diesel Le Mans car announced in detail


#10 Bill Becketts

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Posted 04 October 2006 - 19:30

I was speaking to someone ( Who should know what he is talking about) recently and he intimated the following...

Audi put their own Diesel fuel "Design" to the ACO for homolgation prior to this years 24 Hours.

Normally the ACO supplies the Petrol fuel used BUT not the Diesel....

"So what" I hear you say.

Well the rumour was that there was a small spillage of fuel in the pits.....and it EVAPORATED :eek:

I thougth Diesel fuel was an oil.......