Engine Power Vs. Engine Displacement Vs. Engine Configuration

[fpv_gtho]

I think that was mainly by virtue of still having a cast iron block whilst everthing else moved onto alluminium

[culver]

It wasn't just an iron block but a heavy one at that. Not quite as bad as the I6 from the Supra. The Toyota motor was famous for how much power the internals could handle. Of course is it really a good thing that a motor can handle over twice it's design power? That basically means the engineers left a lot of weight on the table. I believe the Supra turbo I6 is around 600lbs while the weakest of the LSx motors, the LS1 was 345hp (same as the stock Supra turbo) yet weighted in at under 500lb with flywheel. The LS1 can't handle as much power with out internal upgrades but it doesn't carry so many unneeded pounds either.

[pimento]

Was there ever a racing M3 with an I6?

[henk4]

Was there ever a racing M3 with an I6?

Well, the first M3s used the M1 engine, which according to Baretzky, was rather a problematic engine in high tune. The current M3 engine is used as base for the Judd LMP2 engine, but that is a V8.

[culver]

I thought the first M3s used a 2L I4.

[henk4]

I thought the first M3s used a 2L I4.

I stand corrected....the M5 used the M1 engine.

[Ferrer]

The racing M3 E36s did use the staright six, didn't they?

And the original E30 M3 actually used a 2.3 litre four cylinder, later upgraded to 2.5 litres.

[pimento]

Yea, so I was wondering purely based on if they learned anything from racing the M1 with future racing I6s.. or if it was just 'don't bother'.

[Ferrer]

Well, wasn't the M1 race engine more or less derived from the ones in the CSLs? If so, it should have been quite well proven by the late 70's and early 80's.

Group A 635CSis also used a similar engine didn't they?

[henk4]

Well, wasn't the M1 race engine more or less derived from the ones in the CSLs? If so, it should have been quite well proven by the late 70's and early 80's.

Group A 635CSis also used a similar engine didn't they?

Yes it was, but I guess for the M1 specs, the engine reached its limits.

[csl177]

I stand corrected....the M5 used the M1 engine.

Sort of... the S38 was a development of the M88. Von Falkenhausen had that shit DOWN.

[pimento]

Sort of... the S38 was a development of the M88. Von Falkenhausen had that shit DOWN.

S38 was only use in the US, the rest of the world had the M88.

[RacingManiac]

Dr. Ulrich Baretzky, now working for the Audi engine department, was recently quoted about Aston Martin's choice for a new LMP1 engine, being a two litre in line 6 turbo. He said it was about the worst route they could go, as such engine could never be strong/stiff enough. It has already been proven by Aston's continuing engine problems ever since they got it running.
.

LMP engine though is not just engine, its part of the chassis and carries all the suspension load. Looking at that kind of requirement straight 6 indeed does not make much sense(saying its worst route though is probably overstating it, since an inline 8 will definitely be worse...lol). Its not that I6 is bad for a powerplant, just considering all the requirements for an engine in a modern LMP car that it is definitely not the conventional way to go. It'll be interesting to understand AMR's reasoning for going that route...

I don't think racing(especially nowadays) is the best place to compare layout, displacement and power to determine what is good or bad. With the use of equivalency and restrictor and displacement limits, there is an optimum design you are trying to hit under those constraints. BMW went to a V8 in their M3 GTR in 2001 from the I6 because they needed more displacement to work with the restrictor size and the 3.2 I6 wasn't doing it for them, even though maybe the peak power of the 6 was probably not that far off the 4L V8. Same reason why the racing flat 6 of the 911 got bigger and bigger over the year....

[henk4]

In an LMP the engine is not part of the chassis AFAIK, LMPs use carbon tubs, which can eassily accomodate different engines, see for instance the Lolas, which can host a whole variety of engines, ranging from the V12 Aston to the 2.8 Acura twin turbo, the M3 Judd engine or the Toyota 3.4 litre LMP1 engine and in LMP2 guise the 4 litre Nissan V8.

[RacingManiac]

They use it as a stress member, if not fully at least partially. The gearbox bolts straight onto the back of the block. If not you'll need a lattice work of tubular or carbon frame around it to carry the load.

Aston Martin AMR-ONE | Racecar Engineering | Race car technology explained

The long and narrow block of the I-6 means AMR needs the trusses on the side of the engine to carry some load.

Compare that to something a bit more bespoke:
Peugeot 908 HDI FAP | Racecar Engineering | Race car technology explained
Porsche RS Spyder Evo - High Resolution Image (5 of 24)

The engine carries all the load between the gearbox and the tub.

For chassis designed with multiple type of engine, chassis bracing is usually needed since the engine may or maynot be designed to the required stiffness, and the pickup points are not necessarily the same. And the gearbox are not necessarily limited to one type.

The fully stressed engine is more "efficient" design, since you are using a part to do more work, you tried to strive for that but it may not work out all the time. AMR having a clean slate design and a bespoke powerplant and not go with something like that is one more reason why its puzzling...

For something with a unstressed motor, you just need to look at a Daytona Prototype:

Riley Mk XX Porsche - High Resolution Image (12 of 12)