LMP1 diesel performance adjustment

[SebringMG]

Qulaifying this year may show just how quick the diesels at LM can go after all i think it is a safe bet that Peugeot will be gunning for the front row!!! I doubt it matters too much if they cross the 'non' line either - if they both pull3:30 laps and all the petrol cars struggle along at 3:35 then the ACO will slow them down.

[Spyderman]

Originally Posted by SebringMG

Qulaifying this year may show just how quick the diesels at LM can go after all i think it is a safe bet that Peugeot will be gunning for the front row!!! I doubt it matters too much if they cross the 'non' line either - if they both pull3:30 laps and all the petrol cars struggle along at 3:35 then the ACO will slow them down.

I wish I shared your optimism , and above all your seemingly unwavering faith in the ACO.

[gwyllion]

This is facts, not optimism. ACO has stated that LMP1 should be faster than 3:30 and that LMP2 should be 1.5% slower. They stear the rules using this criteria.

[Spyderman]

Originally Posted by gwyllion

This is facts, not optimism. ACO has stated that LMP1 should be faster than 3:30 and that LMP2 should be 1.5% slower. They stear the rules using this criteria.

Surely you mean not faster than 3:30.
And of course you think this is a good thing?

[Spyderman]

Originally Posted by gwyllion

I just calculated for you what the turbo pressure would be for a 6.0 turbo engine (namely none ). You really want to know it for a 5.5 turbo? 1090 mbar absolute pressure. Yes that is 0.09 bar over pressure
In that case just wait one year, untill ACO re-evaluates the diesel performance. If Audi and Peugeot go under 3:30 at Le Mans, I am quite sure the restrictor size/turbo pressure for diesels will be reduced.

You just don't get it do you?
I was'nt seriuosly suggesting that gasoline turbos move to 5.5L (go back to my post and you will find that I said that the reduction of diesls to 4L was exactly what we needed).
Anyway, you calculations are only valid using the current indexes.

[Hammerdown]

Originally Posted by canam

If something needs to be done, restrict the fuel flow. Diesels are not particularly sensitive to restrictor sizes.

Absolutely. Fuel flow measured in units of energy over time and free up the engine regs completely. Any engine boffs out there like to hazard a guess at what would float to the top? Sounds simple, what's stopping them from doing it?

[chewymonster]

Originally Posted by gwyllion

It is just a fact that diesels need more displacement (boost) to produce a comparable power output as gasoline engines. They can only rev to 4500 rpm, while supercharged gasoline can go to 8000 rpm. Remember power = torque x revs and torque = displacement x boost (some simplification involves ).

Just compare some Audi production engines:

• 4.2 V8 TT (RS6 Plus): 353 kW/480 bhp and 560 Nm
• 4.2 V8 TDI (A8/Q7): 240 kW/326 bhp and 760 Nm
• 6.0 V12 TDI (Q7): 368 kW/500 bhp and 1000 Nm

Absolutely true. Diesels and gasoline enignes make about the same hp per liter currently.

3.0 TDI=240 hp, 3.1 FSI=255-265 hp. But Audi quotes the 3.0 TDI A5 .2 seconds quicker to 100 km/h (62 mph) than the 3.1 FSI gasoline engine.
4.2 TDI=326 hp, 4.2 FSI=350 hp. But again Audi quotes the TDI version of the A8 a tenth or so quicker to 100.
6.0 W12 Gasoline=older non FSI engie=450 hp. [550 hp with turbo] compared to the 6.0 V12 TDI with 500 hp (the newest TDI)

So as you can see turbo diesels have about the same power per displacement as naturally aspirated engines of same displacement. This is exactly what we see in P1 with 5.5 diesels and 5.5 Judds.

The rest is up to the factory/privateer debate. The fact is that there is no factory gasoline P1 out there. The Fernandez Lola ran a 1:49.536 as its fastest lap, the Horag Lista could only manage a 1:54.149. Same chassis, one with a privateer engine and the other with a factory engine.

BTW: Horag lists their 3.4 V8 making 550 hp @10,500 RPM. The Acura engine must be much superior as evidenced by the performance difference. How much is it packing?

[Hammerdown]

Interesting that the HoragLista is so slow. It has Michelin tyres and decent drivers. The more I think about it, it seems that the Lola chassis doesn't really like big V engines. Seems perfectly happy with straight-four turbos. Note that the Mazda engined car was faster over a single lap than the Fernandez, and that was on Kumhos. Will be intriguing to see how the various chassis/engine combinations work out in LMS this year as we've got a good mix.

[minimangler]

its all about the power
as we've seen in the alms, adding weight don't work!
strangle the smokey b*****ds!

[gwyllion]

Some first performance comparison of Peugeot 908 vs petrol competitors during HTTT test.

lap times:

• Peugeot 908 HDi: 1:44.382
• Charouz Lola Judd: 1:44.766
• Rollcentre Pescarolo Judd: 1:45.308
• Pescarolo Judd: 1:45.877
• Courage AER: 1:46.645
• RfH Dome Judd: 1.46.746
• Chamberlain Lola AER: 1.48.636

Of course Peugeot did a lot of testing at HTTT and has top drivers.

top speed:

• Charouz Lola Judd: 320 kph
• Rollcentre Pescarolo Judd: 316 kph
• Chamberlain Lola AER: 315 kph
• Peugeot HDi: 299 kph

Peugeot is said to run with lots of downforce; as did Audi last year because they had power to spare. And the Peugeot gets to its top speed very quickly (because of huge torque).

[gwyllion]

DSC had a talk with Minassian and he claimed that they were really pushing and that the car is not quicker. He also claims they can have torque or top end speed, but not both and that they are running medium downforce (not high downforce setup). All this sound hard to believe.

[gwyllion]

Originally Posted by gwyllion

lap times:

• Peugeot 908 HDi: 1:44.382
• Charouz Lola Judd: 1:44.766
• Rollcentre Pescarolo Judd: 1:45.308
• Pescarolo Judd: 1:45.877
• Courage AER: 1:46.645
• RfH Dome Judd: 1.46.746
• Chamberlain Lola AER: 1.48.636

The latest DSC reports suggest the lap times are a bit different: Rollcentre (1:44.540) beats Peugeot (1:44.6).

[gwyllion]

Originally Posted by gwyllion

top speed:

• Charouz Lola Judd: 320 kph
• Rollcentre Pescarolo Judd: 316 kph
• Chamberlain Lola AER: 315 kph
• Peugeot HDi: 299 kph

I just checked the official top speeds in http://www.lmes.com/2007/uk/download...nd_session.pdf and this tells Peugeot had a top of 310 kph.

[minimangler]

Originally Posted by gwyllion

DSC had a talk with Minassian and he claimed that they were really pushing and that the car is not quicker. He also claims they can have torque or top end speed, but not both and that they are running medium downforce (not high downforce setup). All this sound hard to believe.

i pointed this out in the ricard test threas, but
a) they probably aren't at full chat- they have no reason to go flat out and reveal their potential yet.
b) even if they are, you can bet they push like hell to sort all these problems out ASAP if they are slower, because they have such a huge budget (unless they havent got a huge budget, any ideas?)

[gwyllion]

Peugeot replace the HDi engine and did 1:43.709 this morning.

[gwyllion]

Henri Pescarolo still has a clear vision on what needs to be changed to make petrol competitive again.

Tout le monde connaît aujourd’hui la puissance d’un moteur diesel puisque c’est une chose qui a été communiquée. Je sais bien qu’il est très compliqué, même pour un constructeur, de mettre au point une voiture qui utilise cette technologie. Mais, Ã* partir du moment où nous avons le même poids, et une centaine de chevaux en moins, peut on vraiment parler d’équivalence ? Lorsque nous sommes passés en hybride en 2005, nous avons eu une augmentation réglementaire des brides. En rythme de course, nous avons gagné plusieurs secondes. Aujourd’hui, avec une augmentation d’environ 9% des brides, un proto essence peut rivaliser équitablement avec un proto diesel.

quick and dirty translation (with some babelfish help)

Everyone knows today the power of a diesel engine since it is something that has been communicated. I know well that it is very complicated, even for a manufacturer, to develop a car which uses this technology. But, as from the moment when we have the same weight, and a hundred horses less, can one really speak about equivalence? When we passed to hybrid in 2005, we had a increase in the restrictors. In race pace, we gained several seconds. Today, with a restrictor increase of approximately 9%, a petrol prototype can compete equitably with a diesel prototype."

source: http://www.endurance-info.com/article.php?sid=3384

[Bentley03]

Originally Posted by minimangler

b) even if they are, you can bet they push like hell to sort all these problems out ASAP if they are slower, because they have such a huge budget (unless they havent got a huge budget, any ideas?)

I believe the budget was quoted at 100,000,000 euros over the three years.

[minimangler]

Originally Posted by Bentley03

I believe the budget was quoted at 100,000,000 euros over the three years.

jeeee-sussss!
mind you, thats not that much if you look at r+d. at least they're serious.

[Flat12-Aircool]

So now the first race is over what can we see? Well, the quickest Peugeot lap was 2.5 seconds faster than the nearest Petrol engined LMP!

Anybody else like to defend the indefensable and say that the ACO have got it right? To all those posters who keep saying "let's just wait and see", well now we have seen and quite frankly it Stinks.

The ACO need to increase the size of Petrol restrictor's by a few millimetre's Now, not next year. We don't need to wait and see anymore, once Peugeot iron out the last remaining Gremlins it's just going to be an ALMS esq. "cakewalk" farce all over again.

[chewymonster]

Again, it all comes down to the fact that there is no factory gasoline P1. The P2 winning Horag Lista was 3 second slower per lap than the factory Porsches/Acura at Sebring.

[bil588]

Originally Posted by chewymonster

Again, we have yet to see what a factory P1 gasoline powered race car can do.

the ACO should not have to wait until one comes to give diesels the same displacement as petrol engines

[chewymonster]

Originally Posted by bil588

the ACO should not have to wait until one comes to give diesels the same displacement as petrol engines

Where are my 6 liter turbocharged gasoline engines?

[bil588]

huh?

[chewymonster]

The diesel displacement is 5.5 liters. So is the gasoline engine. The diesel gets a turbocharger. If you look at road going engines, you see a very similar situation.

[Purist]

The diesel that Audi uses in the R10 is NOTHING like what road machinery uses, so that makes comparisons there very difficult. And frankly, I have a VERY hard time rationalizing that the diesel turbos need 37.5% more displacement than the petrol turbos (5.5-litres for diesels vs. 4.0-litres for petrol turbos).

What's even more out of whack is that turbo diesels are allowed 5.5-litres, but naturally aspirated petrol engines are only allowed 6.0-litres. Turbos (like on the Porsche 935), or two-stage supercharging (a la Mercedes W163 and Alfa Romeo Type 159 Alfetta), can reasonably double the horsepower of a given naturally aspirated engine.

Diesel burns more efficiently, and contains more potential energy per volume than petrol, so how exactly can the ACO diesel/petrol regs be particularly well-matched as they are?

And even if you restrict the diesels on horsepower to comparable levels (and they do seem to be fairly close in that department with 600-650hp for most engines), the diesels still have substantially more torque. Heck, do any of the petrol engines give 700ft-lbs of torque, let alone 850+ft-lbs?