LMP1 diesel performance adjustment

[chewymonster]

Originally Posted by JAG

Wont the Cosworth turbo be in the back of the (strongly) rumoured Forsythe Courages?

That is what I thought, but information in this thread says that it won't happen. I really do want to see that, as the Cosworth engine should match the Audi R8's engine on technology. (power and efficiency hopefully)

[gwyllion]

Peugeot did not like the recent regulation change.

« The problem areas are the ones which have been forgotten by those opposed to the diesel fuel equivalence rules that have recently been published. You must not forget how complex it is to design a diesel sportscar. People focused only on the advantages that the diesel has. But they forgot the difficulties. We have to face the mass distribution problem which can't be as good as a petrol engined car. We also have to cope with the higher heat exchange of the diesel radiators and intercoolers. We do need bigger ones than the petrol engined cars and it increases the drag in a very significant way. You must not believe that you just need to place a diesel engine in an existing LMP1 chassis to gain 4 seconds per lap! Technical difficulties are real and we are discovering them every day. That's the reason why we believe that the current equivalence rules are good. Because they take into account not only the benefits of the diesel engine but also its disadvantages. Now the organisers have decreased our tank capacity to 80 litres. OK, we'll try to deal with that, but they must not go any further in that balance. I'm genuinely convinced that a really good petrol engined LMP1 car could be competitive.

I would add that if you want manufacturers to come into sportscar racing, you have to offer a true technical stability. You can't invest that much money and see rules changing every other day. And above all, it is unacceptable to change the rules before we've even entered into the competition, because we've made our decision to come to the competition based on a set of precise technical regulations... »

source: http://www.endurance-info.com/article.php?sid=2850

[henk4]

Originally Posted by gwyllion

Peugeot did not like the recent regulation change.
source: http://www.endurance-info.com/article.php?sid=2850

do you like shooting at a moving target? (or in case you rightly don't like hunting trying to score in a goal with moving posts?)

[gwyllion]

According to Murphy the Bear, IMSA will impose some extra performance adjustment. The minimum weight for petrol cars will reduced to 880 kg. IMSA also wants to throw away the LMP2 5% restrictor reduction, but they prefer to discuss this with ACO and Audi.

To be completely fair, one would need to shrink the diesel fuel tank with 3 liters (from 81 to 78) and put the minimum weight of petrol car at 860 kg.

source: http://murphythebear.com/blog/2007/0...phy-gets-help/

[AU N EGL]

Originally Posted by gwyllion

Peugeot did not like the recent regulation change.
source: http://www.endurance-info.com/article.php?sid=2850

. . .it is unacceptable to change the rules before we've even entered into the competition, because we've made our decision to come to the competition based on a set of precise technical regulations... »

Would they like some cheese with that whine ??

Get over it. Anyone who thinks racing IS only between the Green and Checkard flags is living in the dark ages. Poltics and posturing is all part of motorsports.

[gwyllion]

Originally Posted by gwyllion

According to Murphy the Bear, IMSA will impose some extra performance adjustment. The minimum weight for petrol cars will reduced to 880 kg. IMSA also wants to throw away the LMP2 5% restrictor reduction, but they prefer to discuss this with ACO and Audi.

IMSA has released Bulletin 07-06

• Lola EX257 can race in Laguna Seca 2006 configuration (860 kg)
• Lola B06/10, Zytek 06S and Creation CA06/H01 can race in Laguna Seca 2006 configuration but minimum weight of 890 kg
• LMP2 can Laguna Seca 2006 configuration; so restrictor size of 2006 (no 5% reduction and AER gets bigger restrictor/higher turbo boost)

[Flat12-Aircool]

And now we have "unconfirmed" reports of consistant 1:44's and even a 1:43 at the Sebring test!

Nice one Mr ACO, thanks a lot for your unbiased and even handed regulations for 2007. It must have been a real headache to change the fuel tank to 81 litres, thank you so much as it improves competition 10 fold!

[chewymonster]

Originally Posted by Flat12-Aircool

And now we have "unconfirmed" reports of consistant 1:44's and even a 1:43 at the Sebring test!

Nice one Mr ACO, thanks a lot for your unbiased and even handed regulations for 2007. It must have been a real headache to change the fuel tank to 81 litres, thank you so much as it improves competition 10 fold!

What is wrong with a 1:44 Sebring lap. The P2s (with the smaller restrictors) turned 1:46 (so with some more running and last year's restrictor) I am sure the P2s will be able to run 1:45. The ACO said that the P2s should be about 1% slower, which is about the difference between 1:44 and 1:45. I think that Porsche/Acura can make a P1 car that will be a bit quicker than their own P2 race car.

The R10 will race fast enough to beat the P2s (that are obviously making quite a bit more hp than they quote)

Is this hard to understand?

[Flat12-Aircool]

Originally Posted by chewymonster

What is wrong with a 1:44 Sebring lap.

It beats last years qualifying lap record by a whole second, and apparently this is not just the "occasional lap" we're talking about.

Originally Posted by chewymonster

The ACO said that the P2s should be about 1% slower, which is about the difference between 1:44 and 1:45.

They said 1.5%, plus the R10 is really built for Le Mans long straights so it's not surprising that the LMP2's are a bit closer at Sebring.

Originally Posted by chewymonster

I think that Porsche/Acura can make a P1 car that will be a bit quicker than their own P2 race car.

You think so? Even at the regulation 925kg on a mostly twisty circuit, and fast enough to close and overtake the 2 seconds+ gap with the R10? Creation who are a quality team only have half a chance at 890kg.

If such a car from Porsche/Acura could be faster than the R10 at Sebring it would almost certainly be at the expense of outright speed at Le Mans.

Originally Posted by chewymonster

The R10 will race fast enough to beat the P2s (that are obviously making quite a bit more hp than they quote)

No doubt that is true, Audi are the sand bagging experts as witnessed at last years Le Mans.

[chewymonster]

Well, whose fault is it that a (factory) P2 racer is quicker than a P1?

[HORNDAWG]

I think that there should have been a fuel tank inlet restrictor change and compensation weight added in the fuel capacity change. Otherwise it is tantamount to a gain versus the restriction it is meant to be!

L.P.

[chewymonster]

Originally Posted by HORNDAWG

I think that there should have been a fuel tank inlet restrictor change and compensation weight added in the fuel capacity change. Otherwise it is tantamount to a gain versus the restriction it is meant to be!

L.P.

This is not a restriction but rather making sure that all P1s have the same amount of energy on board. A liter of diesel has more energy than a liter of gasoline (about 10%) There is no need to add extra weight as there is already a minimum weight limit set for the R10. The fuel tank inlet has already been reduced for the R10, and diesel takes longer to fill up the same volume. It is unlikely that 81 liters of diesel will take less time to fill up than 90 liters of gasoline. But, it is likely (especially in Le Mans) that the R10 would have more fuel (% wise) left in the tank than the gasoline P1 if it doesn't do any extra laps.

It beats last years qualifying lap record by a whole second, and apparently this is not just the "occasional lap" we're talking about.


But it is ok for a P2 Porsche RS Spyder to be 1 second+ quicker than last year's qualifying time? And this is with the smaller restrictor, it is likely that this year a P2 Porsche Spyder will be about 2 seconds quicker than last year.

Stupid progress.

[gwyllion]

In 2006 the fuel flow restrictor was different for diesel and petrol: 38 mm vs 33 mm. Diesel has a higher viscosity so it flows slower. By having a different flow restrictor refueling 90 liters of diesel and petrol takes the same amount of time.

After Le Mans IMSA started changing the rules to slow Audi down. The first was to reduce the fuel flow restrictor for diesels to 33 mm (see here). This way refueling toke longer for diesel, but the motivation is that because diesel has more energy, the same amount of energy per time will enter the fuel tank.

The current regulations permit the same 90-liter tank on both diesel and gasoline cars but permit the larger restrictor on the refueling rig of diesel cars because of the different viscosities of the fuel.

"The original intent was to permit the full volume of the tanks to be filled in the same time," said Mayer. "However, diesel is a more energy-rich fuel for any given volume. The change that we have implemented means that the energy delivered will be similar, for the diesel versus gasoline, for the same length of refueling."

Of course diesels still had the same tank size and thus higher fuel economy.

In 2007 ACO changed the fuel tank capacity to have the same amount of fuel energy. Diesel cars still have the refueling restrictor advantage (see here). Filling the complete tank with diesel (81 liters) will go quicker than refueling for petrol cars (90 liters).

The whole energy equivalence is nice, but total refueling time should be the same and at the moment it is not.

[JAG]

Didn't Martin Short say the improved Radical lapped Donington 1+ second quicker than in August at the LMS race?

Wouldn't you expect the improved Creation, Zytek, Pescarolo etc. to also be a second plus quicker than last year?

It's called development.

[Flat12-Aircool]

Originally Posted by chewymonster

But it is ok for a P2 Porsche RS Spyder to be 1 second+ quicker than last year's qualifying time? And this is with the smaller restrictor, it is likely that this year a P2 Porsche Spyder will be about 2 seconds quicker than last year.

Stupid progress.

Well in my original post I said that there have even been reports of 1:43's, so it's infact more like 2 seconds faster for the R10.

And yes one would expect the LMP2 Porsche to be faster this year given it's recently announced makeover, but the fact that it's only 1 second faster and not 2 seconds faster is because of sensible regulation on the part of the ACO to maintain a 1.5% gap. It's a pity that because of Diesel favouritism by the ACO, LMP1 is so weak in the ALMS that IMSA have been forced to ignore the regulation to keep the LMP2's nipping at the R10's heals.

[JAG]

Acura are only using P2 as a stepping stone.

Porsche who knows, but you wouldn't bet against a Porsche P1 in 2008.

[gwyllion]

Harmut Kristen does not like the current ACO regulations. Porsche will not go to LMP1 unless equivalence between petrol and diesel engines gets revised.

That's also because we don't agree with the current ACO-Le Mans regulations: in LMP1 there absolutely isn't equivalence between petrol and diesel engines, the latter being undoubtedly advantaged.

This is the most important parameter that, in our opinion, doesn't work.

He claims none of the ALMS LMP2 teams applied for a Le Mans ticket because they could not challenge for overall victory.

Our teams have decided not to participate and we are not interested in racing directly with an LMP2 class car with which we can't aim for overall victory.

We've never done that except in some rare occasions in the past, and it's not in our strategy.

He also does not understand what Audi is complaining about.

I don't understand Audi's complaint.

If there had been an increase by 5% of the intakes in LMP2 it would be understandable, but on the contrary they remained the same as they were in 2006.

Now they threaten to retire from ALMS? If a top team or a top car leaves it's always a loss.

In any case, with or without the reduction of the intakes in LMP2, Audi would win anyway, therefore the decision to stay or leave ALMS is completely up to them.

source: http://www.autosport.com/news/report.php/id/56999

[bil588]

how about the same engine displacement?

4.0 liters for turbos?

[Spyderman]

Originally Posted by bil588

how about the same engine displacement?

4.0 liters for turbos?

That's exactly what is needed!
Unfortunately it won't happen.Peugeot has invested too much under the current diesel rules.
The other soultion of course, would be to allow for 5.5 L Gasoline Turbos

[gwyllion]

Originally Posted by bil588

how about the same engine displacement?

4.0 liters for turbos?

In that case the diesel should run with ridiculous high turbo boosts. Higher boost put even more stress on the engine as it runs with very high compression ratio already.

Just look at the current rules:

• gasoline supercharged (more than 2 valves/cilinder)
  • 2000 cc: 3000 mbar
  • 4000 cc: 1500 mbar
• diesel supercharged
  • 4000 cc: 3870 mbar
  • 5500 cc: 2940 mbar

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

[gwyllion]

Originally Posted by Spyderman

The other soultion of course, would be to allow for 5.5 L Gasoline Turbos

In that case you end up with a ridiculously low turbo boost

Again look at current rules for supercharged gasoline.

• 2000 cc: 3000 mbar
• 3000 cc: 2000 mbar
• 4000 cc: 1500 mbar

If you allow a displacement of 6000 cc, you will have a turbo boost of 1000 mbar. Remember that the maximum supercharging pressure is absolute. So in case of a 6.0 liter engine you end up with a normally aspired engine

[Spyderman]

Originally Posted by gwyllion

In that case you end up with a ridiculously low turbo boost

Again look at current rules for supercharged gasoline.

• 2000 cc: 3000 mbar
• 3000 cc: 2000 mbar
• 4000 cc: 1500 mbar

If you allow a displacement of 6000 cc, you will have a turbo boost of 1000 mbar. Remember that the maximum supercharging pressure is absolute. So in case of a 6.0 liter engine you end up with a normally aspired engine

Yes! I was actually being facetious.
The current rules don’t even allow for a 5,5 L turbo, so why bring the current rules into the equation?
If you are going to change the rules, then obviously you are going to have to change the boost pressure indexes.

[SebringMG]

Until there is a manufacturer running a petrol engine in P1 then any performance balancing in P1 is largely hit or miss. Last year they got it wrong this year i am more hopeful - at the end of the day the ACO will stay on the side of the manufacturers in preference to privateer teams, the fact that the two major manufacturers are both diesels means that a slight bias at first can be expected. When Acura go P1 expect this to be a fully level playing field....or even if Porsche ever decide to go P1.

[gwyllion]

Originally Posted by Spyderman

The current rules don’t even allow for a 5,5 L turbo, so why bring the current rules into the equation?

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

Originally Posted by Spyderman

If you are going to change the rules, then obviously you are going to have to change the boost pressure indexes.

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.

[canam]

Originally Posted by gwyllion

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.

They won't.

They may run all day and night at 3:30.0000000001 and do 198 laps on a single tank of fuel but they won't cross that 'non non' line.

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