LMP1 Performance Balance

prototype · 22 Apr 2009, 02:31 (Ref:2446724)

DSC has posted the latest efforts by the ACO to balance the regulations between the petrol and diesel entries. I know this topic has been discussed in many other threads, so if this may need to be merged with another thread.

The million dollar question is will these latest efforts actually balance the P1 field at Le Mans.

I also wonder if Audi new about the possibility of these impending changes and subsequently paced the R10s at Barcelona. (Just another internet generated conspiracy theory.)

fiend540 · 22 Apr 2009, 03:51 (Ref:2446737)

It seems that they have kind of jumped the gun, there have been 2 races and while a diesel won Sebring it's not like the Acuras lost due to being way off the pace. As for the lms series the two diesel cars were never really a factor. It's hard to tell if the ACO made a right decision yet because imo we haven't had a real good race between the top diesels and the top petrol cars.

Porsche917K · 22 Apr 2009, 04:23 (Ref:2446745)

The Acura was way off pace at Sebring... it qualified on pole but that didn't even get them through the first corner in the lead.

Hugewally · 22 Apr 2009, 05:20 (Ref:2446755)

The fueling restrictors should've been the same from the very start. None of the diesels in ACO style racing have use anything that isn't close to rocket fuel in viscosity. This ain't your dad's old pickup trunk diesel they've been using. Spill it on the ground and watch is evaporate faster that racing gas...

Hugewally · 22 Apr 2009, 05:21 (Ref:2446756)

Quote:

Originally Posted by Porsche917K

The Acura was way off pace at Sebring... it qualified on pole but that didn't even get them through the first corner in the lead.

IMO, the Acuras were given the pole by the lead P1 runners...

Spyderman · 22 Apr 2009, 05:40 (Ref:2446760)

Couldn't agree more Huge.

Lola T70 · 22 Apr 2009, 06:27 (Ref:2446773)

But, Hugewally, are you forgetting Mid Ohio a couple of years ago when the P2's jumped the Diesel P1's in the pits because they refuelled so much faster!

I would expect ACO to know the viscosity of the Shell gas and diesel, considering they mandate everyone uses it I am sure Shell provide this information.

gwyllion · 22 Apr 2009, 06:33 (Ref:2446775)

For me this poll comes a few weeks too earlier. The 2 races in which we have seen a diesel-petrol battle are a bit special: the Acura is not your standard LMP1 petrol car (small engine and cornering speeds the drivers can not cope with) and in Barcelona the diesel Audis were in the hands of highly unexperienced drivers.

I will fill in this poll after Spa. BTW I except Peugeot to win the LMS race because it is quite normal that a manufacturer with huge resources wins against privateer teams. However, the margin they will have will determine my choice.

gwyllion · 22 Apr 2009, 06:48 (Ref:2446776)

Quote:

Originally Posted by Hugewally

Spill it on the ground and watch is evaporate faster that racing gas...

I thought this ghost story would be gone by now

gwyllion · 22 Apr 2009, 07:06 (Ref:2446784)

Quote:

Originally Posted by prototype

I also wonder if Audi new about the possibility of these impending changes and subsequently paced the R10s at Barcelona. (Just another internet generated conspiracy theory.)

Yeah, right. They asked the drivers to frequently spin the car and drive it off track. All this to fake that they were strugling with the balans of the car and with a lack of downforce. Perhaps they even ran with even less power than the 10% restrictor cut gives them

cdsvg · 22 Apr 2009, 07:18 (Ref:2446789)

I don't have any problem with this change, nor the 10% restrictor cut for this season - will be interesting to see whether the 30kg helps neutralize the diesel slingshot out of low-speed corners due to the torque advantage.

At some point though you are no longer trying to balance diesel and petrol, but you are trying to balance privateer with factory - not a good thing. If anything, the performance of the Kolles R10s at Barcelona only confirmed my opinion that in 2008 at least, the gap between the diesels and the petrols was primarily due to the high level factory support, not the engine. The diesel engine cars have more power - sure - but where would Acura be with a full-on Peugeot budget and a 4L twin turbo engine?

gwyllion · 22 Apr 2009, 07:23 (Ref:2446790)

Quote:

Originally Posted by prototype

DSC has posted the latest efforts by the ACO to balance the regulations between the petrol and diesel entries.

It would have helped if you listed the rule changes ACO has imposed for people who don't have access to DSC. I just read them on lemans.org

fuel flow restrictor: 38 mm -> 33 mm (like petrols)
current weight + 30 kg

Both make sense.

The bigger fuel restrictor was necessary in the beginning (2006) when the cars had the same fuel tank in order to guarantee that refueling takes the same amount of time. With the smaller tank (81 vs 90 liter) this gave the diesels an advantage.

The added weight will take away a bit of the torque/acceleration advantage diesels have now.

Speed-King · 22 Apr 2009, 08:02 (Ref:2446809)

Isn't the Peugeot still a bit overweight, whereas the Audi has to be balasted to meet the weight requirements?

Gotta love the French...

gwyllion · 22 Apr 2009, 08:29 (Ref:2446819)

ACO actually listed to Audi. The rules don't say that the minimum weight for diesels is 930 kg from now on. The cars will be weight to see if they are above 900 kg and next 30 kg must be added.

So in practice Audi will go from 900 to 930 kg, but Peugeot will go around 915 kg to 945 kg.

Spyderman · 22 Apr 2009, 09:32 (Ref:2446853)

Won't effect Le Mans outcome.

deggis · 22 Apr 2009, 10:58 (Ref:2446901)

showed that the diesel-engined cars still enjoyed an advantage.

Breaking news? With the way 2011 regs look, ACO is going to make lots of these announcements in future.

LeMans.pt · 22 Apr 2009, 11:07 (Ref:2446903)

I prefer to wait and see what happens in Spa....

CarolK · 22 Apr 2009, 13:38 (Ref:2447006)

Why not just have LMP1 Diesel and LMP1 Petrol and let the manufacturers run in either or both classes and not try to make two totally different engines run as one?

Félix · 22 Apr 2009, 13:41 (Ref:2447010)

Losing a couple minutes total in the pits over Le Mans won't change the multi-lap gap to privateers you normally see at the end of the race.

Adding weight will be felt on street courses and maybe at the beginning of acceleration on straights.... But at Le Mans, the difference wont be too big at the end of the straights. All the LMPs were struggling to overtake the Kolles Audis at Barcelona (i was there) and complaining about it, while the Acura was losing seconds in the straights at Sebring. Since power or drag is not changed, the effect at Le Mans will be minimal. I predict still over 5 seconds advantage for the pole diesel lap over the first petrol one. Kolles will probably be very close or in front of the petrol-polesitter. The R10's average chassis will be in it's element and Joest will be next door...

The problem is that the diesels still have a sizable but unknown power advantage (now <100hp) and their HUGE torque. It's still twice the figure the gasoline P1s have. That means they still accelerate like trains and can take draggy bodies and wings with them to have a real downforce advantage... and are still too fast at the end of the straights. Put a Judd in the R15 and I believe you have something like the Acura, or at least too draggy for an atmo.

What I'd do is to try to bridge some of the advantage by giving the NA P1s a few concessions. They could open up the restrictor and be close to 700hp... but they'd still have the same torque. Diesel technology has to have advantages so I'd leave power where it is or only move it by ~20hp to make things a bit closer. What petrol P1s need is a way to be able to take more downforce with them and not suffer from more drag (make L/D better for them). I'd say make the mandatory rear wing gurney smaller or take it off (from 20mm) but it's probably impossible to recover the rear balance with the new narrower size of the wing. Alternatively, they could be allowed a more efficient rear diffuser (that's a big chunk of re-engineering for privateers) or the diesels' one could be made smaller (probably by just filling it in, reducing height to 15 cm or less). Imagine tail-happy overpowered diesels! MulsannesMike and other technical-minded people, I'd love to know what you think!?

gwyllion · 22 Apr 2009, 14:33 (Ref:2447042)

Quote:

Originally Posted by Félix

The problem is that the diesels still have a sizable but unknown power advantage (now <100hp) and their HUGE torque. It's still twice the figure the gasoline P1s have. That means they still accelerate like trains and can take draggy bodies and wings with them to have a real downforce advantage... and are still too fast at the end of the straights. Put a Judd in the R15 and I believe you have something like the Acura, or at least too draggy for an atmo.

Torque gives you initial acceleration out of a corner. In this respect diesels are better than turbocharged petrols are better than NA petrols. This advantage can be compensated by giving them more weight. However, this increase fuel consumption and tyre/brake wear.

Power is what is important for acceleration during a long period of time, so shifting through all the gears on a long straight. This is explained in the open letter Henri wrote in 2006. Take away the power advantage of diesels (smaller restrictor/less turbo boost) and things look different in Le Mans.

JHamilton · 22 Apr 2009, 16:38 (Ref:2447125)

Won't make a noticible difference. Further air restrictor adjustments need to be made.

deggis · 22 Apr 2009, 18:13 (Ref:2447192)

Ditch the whole displacement/restrictor petrol vs. diesel based (")equivalency(") system and bring in fuel or energy flow limits with more open engine regs. Basically like next generation of Group C. At least then the winning engine would be genuinely superior, Scott Atherton could say with more confidence ALMS is the leader in green racing and ACO wouldn't have to sh*t their pants with too fast lap times since they could easily adjust the limits.

chewymonster · 22 Apr 2009, 18:26 (Ref:2447208)

Quote:

Originally Posted by deggis

Ditch the whole displacement/restrictor petrol vs. diesel based (")equivalency(") system and bring in fuel or energy flow limits with more open engine regs. Basically like next generation of Group C. At least then the winning engine would be genuinely superior, Scott Atherton could say with more confidence ALMS is the leader in green racing and ACO wouldn't have to sh*t their pants with too fast lap times since they could easily adjust the limits.

Such a rule would greatly benefit diesels.

This new decision is based on way too little data. An ALMS designed Acura whose performance is unknown against the top LMS gas powered cars.

prototype · 22 Apr 2009, 19:00 (Ref:2447241)

This is the first time I can remember that the ACO made regulation changes in the middle of a season.

I do think there still needs to be an air restrictor cut.

Sarthe82 · 22 Apr 2009, 19:44 (Ref:2447269)

Quote:

Originally Posted by LeMans.pt

I prefer to wait and see what happens in Spa....

Same here, and for the first time I'll be watching it LIVE!

View Poll Results: Is there still a Performance inbalance between LMP1 Diesel and Petrol runners
No enough, The diesels will still be faster at Le Mans	31	46.97%
The ACO did too much, the petrol cars will be faster at Le Mans	6	9.09%
Perfect! This may be a better race than 1999!!!	9	13.64%
I have no idea, but now I am extra excited about Le Mans!	20	30.30%
Voters: 66. You may not vote on this poll

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