Peugeot 2010-2011 (Temporarily Closed)

[chernaudi]

Peugeot may come clean about the 908's failures in a few days. A Danish motorsport site says that they interviewed a Peugeot sport engineer who said that it likely wasn't a turbocharger failure. However, when asked if was valvetrain, or bottom end, the interviewee went silent, hinting that it could still be a piston problem.

In Danish, but mentions Peugeot disclosing their findings later this week: http://ing.dk/artikel/109712-den-25-...le-mans-fiasko

[CTD]

Originally Posted by chernaudi

Peugeot may come clean about the 908's failures in a few days. A Danish motorsport site says that they interviewed a Peugeot sport engineer who said that it likely wasn't a turbocharger failure. However, when asked if was valvetrain, or bottom end, the interviewee went silent, hinting that it could still be a piston problem.

In Danish, but mentions Peugeot disclosing their findings later this week: http://ing.dk/artikel/109712-den-25-...le-mans-fiasko

Are you danish Chernaudi?

[gwyllion]

John Brooks also picked up rumors that it might have been a piston failure:

However Peugeot were to suffer even more agonies, first #1 and then #4 had their engines explode in the manner that had afflicted #2 at dawn. Olivier Quesnel maintained a terse "No Comment" when questioned about the root of the problem. In the paddock a whisper of piston broke took hold. It could explain as to how the cars were faster despite a 5% reduction in restrictor size over 2009.

source: http://speedhunters.com/archive/2010...lane-view.aspx

[gwyllion]

Le Mans highlights on http://www.peugeot-sport.com/en/endu...0-le-mans-24h-

[merlot brougham]

I don't know what the big deal is about the exhaust emissions. I have seen it at PLM and Sebring the past two years from Audi and Peugeot. I'm almost certain I have video where you can see it at all 4 of those races in qualifying and at certain points in the race.

I just figured that it was a tree no one wanted to go barking up for fear of alienating the two main (manufacturer) draws in prototype sportscar racing. Or maybe the intent of the rule is not how we are interpreting it?

[Victor_RO]

Originally Posted by merlot brougham

I don't know what the big deal is about the exhaust emissions. I have seen it at PLM and Sebring the past two years from Audi and Peugeot. I'm almost certain I have video where you can see it at all 4 of those races in qualifying and at certain points in the race.

It wasn't on the same scale as this year. Maybe in previous years it was just a wisp here and there, but this time they were properly chugging out diesel smoke when accelerating heavily.

[merlot brougham]

Admittedly I was not in Le Mans this year so I can only go off the video but I assure you, in qualifying trim, coming out of the low speed corners at Road Atlanta last year and at points in the race you saw plumes of exhaust smoke. They even commented on it on Radio Le Mans. Again, just sayin'.

[chernaudi]

Originally Posted by CTD

Are you danish Chernaudi?

No, but someone who was linked the article on Mulsanne's Corner's Facebook page in the discussion area.

So it seems from what I've asked that the theories on the Pug engine failures that it first was piston failure, then turbo failure, and now were' back to piston failure being the culprit, but whether it was due to turbo compressor failure or a valve failure or someother failure won't be know until at least Friday when Peugeot releases the press release. And maybe then the theory on whether or on Peugeot will follow though on their intent on the LMIC or if they'll give up on the 908 and focus on 2011.

[dxk1]

Originally Posted by gwyllion

Le Mans highlights on http://www.peugeot-sport.com/en/endu...0-le-mans-24h-

Is there a reason to call these "highlights"? More like "lowlights" if you ask me. I guess they have to put a nice face on failure as best they can.

DK

[gwyllion]

http://86400.fr/articles/81-24h-du-m...-dexplications has very detailed analysis of what might have gone wrong with the Peugeot engines. Laurent also believes it was a piston failure. When that car is stationary in the pits, the pistons are no longer cooled by the engine oil but the cilinder liners are still cooled by the coolant water. So the pistons expanded too much compared to the liners and got damaged when the engine restarted.

He also points out that the fact the Peugeot had the first pit boxes this year could be a contributing factor. The engine come from full race condition to an immediate stop, without a transistion period (cruising through pitlane). Maybe that is a reason why they did not suffer the problem in their previous Le Mans races

When reading his analysis, I remembered this post of knighty:

Originally Posted by knighty

while you are talking about Peugeots secrets, heres a nice juicy one for you.......the latest issue of race engine magazine has managed to find out that Peugeot are running steel pistons.........this is what allows Peugeot to really crank up the power for qualifying, the reason being a steel piston is more fatigue resistant and generally stronger than its equivalent alloy piston, as used in the Audi R10.......therefore this allows a serious rise in cylinder pressure handling capability, which is achieced by injecting more fuel, lower charge temps, more air etc......which relults in an increase in torque and therefore a significant power increase.

[Victor_RO]

Originally Posted by gwyllion

He also points out that the fact the Peugeot had the first pit boxes this year could be a contributing factor. They have to drive through the pit lane at 60 km/h before the engine gets it proper cooling. Maybe that is a reason why they did not suffer the problem in their previous Le Mans races

They had the first three pit boxes last year as well.

[gwyllion]

Okay, but last year they only raced for 12 hours and then they cruised home because the Audis were too far back.

Laurent also suggests that Peugeot expected the R15+ to be faster than the 908. So they might have gone for a smaller safety margin in the design of the new engine specification for 2010.

[gwyllion]

Originally Posted by gwyllion

When reading his analysis, I remembered this post of knighty.

One addendum: it is possible that Audi uses steel pistons as well in the R15 engine. According to the february 2009 issue of Race Engine Technology:

In fact in 2008 the Audi engine was good for at least 770 bhp. There has been a decrease of intake air restrictor size and boost pressure for 2009 but on-going engine development will have recouped part of that theoretical 10.5% cut – turbodiesel race engine technology is nowhere near as mature as gasoline engine technology. For example, common rail fuel pressure keeps increasing and Audi is only just starting to exploit the potential of the steel piston.

source: http://www.highpowermedia.com/mall/r...036_Sample.pdf

In fact Audi lists Mahle as a partner for Le Mans with the following description:

MAHLE also celebrated successes in Le Mans: For over 12 years the winners of this race were driving with MAHLE pistons, since 2006 with steel pistons that have been especially developed for the high combustion chamber pressures in diesel engines.

source:
http://www.audi.com/com/brand/en/exp.../Partners.html

That suggest Audi has always used steel pistons from the beginning: 2006 = debut Audi R10.

[knighty]

Originally Posted by gwyllion

http://86400.fr/articles/81-24h-du-m...-dexplications has very detailed analysis of what might have gone wrong with the Peugeot engines. Laurent also believes it was a piston failure. When that car is stationary in the pits, the pistons are no longer cooled by the engine oil but the cilinder liners are still cooled by the coolant water. So the pistons expanded too much compared to the liners and got damaged when the engine restarted.

He also points out that the fact the Peugeot had the first pit boxes this year could be a contributing factor. The engine come from full race condition to an immediate stop, without a transistion period (cruising through pitlane). Maybe that is a reason why they did not suffer the problem in their previous Le Mans races

When reading his analysis, I remembered this post of knighty:

I agree with his theory, piston failure originating from a piston-scuff is highly likley, it also explains why there was such a big flame-out, which was basically oil from the crank case igniting in the hot exhaust system......... a modern high performance gasoline or turbo-diesel engine throws half of its total oil flow at the underside of the pistons, if thats not happening during pit stops then they will just cook.......I certainly didnt believe it was a turbo failure as assumed by the eurosport commentators.......good find

[gwyllion]

Perhaps the turbo went as well because of the oil pressure loss

The #1 was the only Peugeot that made it back into the pits. On http://www.youtube.com/watch?v=8_8E2kdk998#t=1m11 you can clearly see that the crankcase was punctured as the engine was leaking oil.

[Samoan Attorney]

Originally Posted by knighty

I agree with his theory, piston failure originating from a piston-scuff is highly likley, it also explains why there was such a big flame-out, which was basically oil from the crank case igniting in the hot exhaust system......... a modern high performance gasoline or turbo-diesel engine throws half of its total oil flow at the underside of the pistons, if thats not happening during pit stops then they will just cook.......I certainly didnt believe it was a turbo failure as assumed by the eurosport commentators.......good find

Piston failure was admitted by someone at Peugeot who would know, to someone at Audi who would understand. As to why, that theory fits but there was also a thought that the French were stretching the physical limits of the steel pistons with the set up of the engine. Still no doubt we will get the authorised version in due course.

[ger80]

why didnt they use a different (cooler) mapping on the inlap then?

[chernaudi]

Then we also gotta go back to Petit Le Mans last year. Audi on the R15(and presumably on the R15 plus) used oil/water heat exhangers like the R8 and R10 had. On the 908, it's been rumored that they used the engine oil as the main cooling medium with water to supplement it.

Could that have caused issues?

[gwyllion]

Originally Posted by ger80

why didnt they use a different (cooler) mapping on the inlap then?

Apparently they did not want to lose any time on the track. Davidson was asked to attack on pit entry, which he did: http://www.youtube.com/watch?v=n0ozSI6KeR8

[gwyllion]

Originally Posted by chernaudi

On the 908, it's been rumored that they used the engine oil as the main cooling medium with water to supplement it.

I don't see anything special on http://www.mulsannescorner.com/Peuge...ng2008-MS4.jpg The radiator (3) is bigger than the oil cooler (2).

As a comparision, this is a shot of the Bentley radiator: http://www.mulsannescorner.com/Bentley-BC11.jpg

I would say the Peugeot radiator is bigger, which corresponds with this statement of Serge Saulnier:

On the aerodynamics side too, it's also needed to have 25 % bigger radiators.

source: http://www.mulsannescorner.com/newsoct06.html

[MulsanneMike]

Originally Posted by gwyllion

I don't see anything special on http://www.mulsannescorner.com/Peuge...ng2008-MS4.jpg The radiator (3) is bigger than the oil cooler (2).

As a comparision, this is a shot of the Bentley radiator: http://www.mulsannescorner.com/Bentley-BC11.jpg

I would say the Peugeot radiator is bigger, which corresponds with this statement of Serge Saulnier:
source: http://www.mulsannescorner.com/newsoct06.html

Quite a few (engine) people I've talked to completely rubbished the oil as a coolant idea.

[gwyllion]

@Samoan Attorney: Did you pick up anything about why the Peugeot was so much faster than the Audi?

I read somewhere that Henri Pescarolo estimated that the Peugeot engine produces at least 30 bhp more than the Audi. In 2006 he wrote in his open letter to the ACO that the Audi R10 was around 3.5 sec a lap faster than his petrol powered car purely because of straight line acceleration and that this corresponds with a difference of power of 60 bhp. So the estimated 30 bhp is good for almost 2 sec. The extra gear of the Peugeot probably also helps in acceleration.

Clearly Peugeot could run with more downforce because of the less draggy coupe shape and their power advantage. Audi had to use less wing to match the top speed of the Peugeots. As a result Audi is 1 sec slower than Peugeot in sector 3 = Porsche curves (see sector analysis). In sector 2 Peugeot gains 1 sec because with its power advantage it can accelerate quicker to its top speed, which is the same as Audi.

After the Wednesday sessions the Audi drivers were also complaining that the R15 did not handle well on the bumps; see for instance here. The extra downforce helps the Peugeots, but perhaps it also has better mechanical grip. The Peugeot drivers could really attack the curbs.

[gwyllion]

In an interview with AUTOhebdo Quesnel firmly denies that the engine failure was the result of a late modification. However, he does confirm that in Sebring a different/older engine specification was used, because the ultimate engine evolution was not yet done.

BTW EI already noticed during a 30 hour endurance test of Peugeot in February that the engine was louder: http://www.endurance-info.com/versio...ance-3651.html.

[Tim the Grey]

Hmmm. When number 1 pulled up in the pits for the last time, there was a nice dark oil trail left...
How would a piston failure cause so much oil to leave it's galleries? Unless it's popped through the liner... and the block!
All of which could link back to the 'hot piston, cold liner' discussed earlier?
Or does someone here know (probably a lot!) more than I???

[gwyllion]

The crank case got punctured when the piston broke. With the #2 and #4 the oil sprayed onto the hot exhaust and ignited, and with the #1 it only leaked on the ground. At least that is the theory.