Audi LMP1 Discussion

[chernaudi]

So you believe (contrary to what Gwyllion has been pointing out, suggesting that Audi may be slightly down on power) that Peugeot and Audi are on par in the engine department and the Pug is just really picky about it's performance window?

[Audi Racer]

Originally Posted by chernaudi

So you believe (contrary to what Gwyllion has been pointing out, suggesting that Audi may be slightly down on power) that Peugeot and Audi are on par in the engine department and the Pug is just really picky about it's performance window?

i dont think its "belief" its pretty common knowledge...tat both the audi and the peugeot are very finicky about tire temps.....this is of course caused by the large front tires

[chernaudi]

If that's the case, why not stick with the normal tire arragement? They have to know that the Acura was pretty useless the first several laps on new tires and after the start and restarts because of issues with getting heat into the front tires.

I know that Audi and Peugeot have purpose built front tires that are far more suited than what Acura had, but it still seems that the wide front tires need to be perfected in both cases. Peugeot has very narrow operating windows that function in the extreme high temperature range for their tires, while Audi has a wider window, but seems to be less effective at the the same high temp ranges that suit the 908.

It's interesting the differing trains of though behind why Audi haven't been able to put a whole race together in the sprint races, but had the car to beat at Le Mans. Some think that Audi are sturggling for power in the shorter races, and some think that Audi have missed the hot setup for Spa and Imola in regards to aero or chassis to optimize their tires.

Personally, I think that Audi are still learning the R18, as is Peugeot with the 908, and Peugeot does have 3.5 more months with the 908 on track. They may've only done a few tests in those weeks, but that's a few more tests than Audi had in that same period of time, and any track time with a new car will help.

Not having been there nor having been able to see the races on TV, I can't tell you exactly why that is--I can only guess based on the info I can find and that ends up being debated. The only guys who know about the R18's issues in the sprint races are Audi Sport employees, and I don't think that they'd willingly talk to most of us about those issues.

And on the Panullo blog, there's yet a new illustration of the R18's front diffuser--It's very similar to the LM version (the Oak Pescarolo-like strakes in the outer section, and the four VG's on the raised inner tunnels), but Audi appears to have added a large strake in each tunnel by Imola.

[gwyllion]

Originally Posted by chernaudi

Peugeot has very narrow operating windows that function in the extreme high temperature range for their tires, while Audi has a wider window, but seems to be less effective at the the same high temp ranges that suit the 908.

We have seen no evidence that the Audi has a wider operating window. The R18 only worked properly during the day time at Le Mans. They struggled during the night and the wet in Le Mans and in the hot conditions of Spa and Imola.

[chernaudi]

Or could the reason why the R18 slowed in the wet at LM was because Lotterer was told to back off because his R18 was the only one still running?

When you consider how much of a handful the 908 was in the dry in the day at LM, a wet track would make any handling issue worse, wouldn't it?

And when the track was greasy (when the medium slicks still worked fine), the Audi was still as fast if not faster than the 908. And it was Peugeot who put at least one of their cars on intermediates when it was sprinkling.

And then there's this: On the last Audi stop, they probably bolted soft tires on the car, while Peugeot had to stick to their old, worn tires to save time. Conclude what you'd want from that, but the fact that the Audi pulled away from the Pug and built up at one point a nearly 20 second lead and then backed off shows me that the Audi is better on a low to medium tire temp range (low to mid range on the tire compound's temp range), while the Pug works better on the higher temp range for the same tire (soft compound at night at LM, and medium compound at Imola).

Of course, if the Audi and Peugeot balance issues are due to the wider front tires, why did they go for the wider fronts in the first place, given what we (and assureidly they) know about the Acura, even if Audi and Peugeot have tires made for the job of being wide fronts, and Acura didn't.

Of course, when does most of the racing occur? In daylight hours. Which depending on the temperatures at Silverstone, Road Atlanta and Zhuhai (Silverstone will likely be cool, Zhuhai will be warm, and Road Atlanta is a bit of a crapshoot--the southern US is typically warm, but who knows with how the weather has constantly flip-flopped in the US all year), who ever gets whichever compound to work will likely have the advantage.

This also likely explains why Audi and Peugeot have done so much testing, as they have slightly different tires that Michelin has made specifically for their cars.

[gwyllion]

Originally Posted by chernaudi

And when the track was greasy (when the medium slicks still worked fine), the Audi was still as fast if not faster than the 908. And it was Peugeot who put at least one of their cars on intermediates when it was sprinkling.

Clearly you did not read the race analysis of Paul Truswell in RCE: http://gb.zinio.com/pages/RacecarEng...16178379/pg-32 Figure 8 of that article compares the lap times of the #2 Audi (Lotterer) and the #9 Peugeot (Pagenaud) during the period of light rain. Both cars were on slicks and on average Pagenaud was 2.5 sec faster!

Also remember that the #7 Peugeot, which was no longer in contention for the victory, was way quicker than the Audi in those conditions.

Originally Posted by chernaudi

And then there's this: On the last Audi stop, they probably bolted soft tires on the car, while Peugeot had to stick to their old, worn tires to save time.

Your speculation is wrong. Audi never ran the soft compound during the race, even during the night they also stuck to the medium compound.

[Audi Racer]

Im confused....are you guys arguing that Andre lotterer is slow? 3.25.6? does that sound slow to you?

[JAG]

Both teams and driver line-ups are evenly matched, if one has an off day, that will be the difference between success or failure.

Before Peugeot arrived, Audi had it so easy you didn't know when they were off their game, they looked unbeatable.

[Victor_RO]

Originally Posted by Audi Racer

Im confused....are you guys arguing that Andre lotterer is slow? 3.25.6? does that sound slow to you?

The subject was the short period in the morning when the track was wet and both the leading cars were on slicks.

[chernaudi]

Originally Posted by gwyllion

Clearly you did not read the race analysis of Paul Truswell in RCE: http://gb.zinio.com/pages/RacecarEng...16178379/pg-32 Figure 8 of that article compares the lap times of the #2 Audi (Lotterer) and the #9 Peugeot (Pagenaud) during the period of light rain. Both cars were on slicks and on average Pagenaud was 2.5 sec faster!

Also remember that the #7 Peugeot, which was no longer in contention for the victory, was way quicker than the Audi in those conditions.
Your speculation is wrong. Audi never ran the soft compound during the race, even during the night they also stuck to the medium compound.

Well, I watched the race, and when ever the Speed guys commented on lap times, most of the time, Lotterer was at least as fast as Pag was. It sprinkled the whole last 4+ hours of the race, and typically Lotterer ran 3:27-3:30s--the same range the Peugeot was running.

The #2 Audi was the only one left, where as the #9 Pug had it's sister cars out there. I feel that had a lot to play into it.

I don't think that the Pug was really much faster in the rain--it's easy to push when you know that you have other cars to pick up the slack or you're out of contention. Also, the #2 Audi was scoring ILMC points, the #9 Pug wasn't--so it had really nothing to lose by pushing.

And at night, Peugeot ran soft tires, where as by your own admission Audi didn't. That probably played into the Pug's increased pace during the night.

Clearly, in the daylight, the R18 is better on the medium tire at the low to mid temp range, where as the Pug needs a track that's either hot enough for the high range of the medium tire to come in, or for it to be cool enough for the softs to be useful.

It's sort of like F1 this year, where tire choice is as important as anything else as far as speed goes.

[Victor_RO]

Originally Posted by chernaudi

Well, I watched the race, and when ever the Speed guys commented on lap times, most of the time, Lotterer was at least as fast as Pag was. It sprinkled the whole last 4+ hours of the race, and typically Lotterer ran 3:27-3:30s--the same range the Peugeot was running.

Except you missed the 20-30 minutes when Lotterer was lapping in the 4:00-4:10 bracket when the track was really wet, and both Pagenaud and Davidson were in the 3:50s and sometimes 3:40s. Those minutes basically cut the leading gap in half.

[chernaudi]

As I said, he was the only Audi left, and it's easy to push when you have teammates to pick up the slack or (if you're a lap down and/or not collecting ILMC points) not in contention to achieve anything. It's also easy to back off when you have a big lead that you can defend and you know that the track will dry out soon. I think that Andre was instructed to try and hold a gap and not be a hero.

That's why in F1 or NASCAR the teams look at their weather radar like hawks--in F1, switching between tire compounds and tread patterns is a major strategy call that can make or break a race, and can make a team and driver a hero or a zero. In NASCAR, all they run as slicks in the Cup series (even at road courses ), so that plays into the stragegy and why there's a mad rush of urgency when rain is forecasted.

And just a general question: Is it fair to say that maybe the wider front tires have made the cars very temperature sensitive as far as changing track conditions? The ARX-02 (which didn't have purpose built front tires like the R18 and 908 do, for reference) was very temperature sensitive until it got heat in it's front tires.

I don't know if it's the case, but it seems like the 908 has a hard time keeping heat in it's tires until it gets up in the high range of the tire's temp range, while the R18 has issues with keeping the tires in their sweet spot in those same ranges. It seems like on the same tire compounds, the cars respond better to opposite conditions until they meet somewhere in the middle, then it becomes an issue of the shoe being on the other foot, pun intended.

[cdsvg]

Too much spare time + a fancy new 3d modelling program to play around with = my idea of how next year's R18 powertrain could look

Still very much work in progress, I haven't hooked up the exhaust to the turbo, I haven't modeled the intercoolers, etc.





There are 4 motor/generators and an energy storage device (battery/flywheel), all in yellow.

• 1: MGU connected to the driveshaft, acting as a KERS device on the rear wheels (exactly the same as in F1)
• 2: MGU on the turbocharger shaft (both harvesting extra energy from the turbine, OR, used like a supercharger to drive the compressor)
• 3: Pair of MGUs on the front wheels acting as KERS, as allowed in the ACO rules.

If I read the rules correctly, then having both #1 and #3 is not allowed, you could only have one or the other (KERS acting on either the front wheels or the rear wheels, not both). I have no idea how #2 would fit in with the rules, or even if it is legal.

Another idea to consider is running the engine water cooling loop, after passing through the engine, through a heat exchanger surrounding the exhaust (aft of the turbo), then sending the coolant through a turboexpander to drive another generator. I dont have the technical background to know whether that would work, and even if so, if it would pay for itself in terms of weight/complexity.

[gustavobamba]

Originally Posted by cdsvg

Too much spare time + a fancy new 3d modelling program to play around with = my idea of how next year's R18 powertrain could look

Still very much work in progress, I haven't hooked up the exhaust to the turbo, I haven't modeled the intercoolers, etc.





There are 4 motor/generators and an energy storage device (battery/flywheel), all in yellow.

• 1: MGU connected to the driveshaft, acting as a KERS device on the rear wheels (exactly the same as in F1)
• 2: MGU on the turbocharger shaft (both harvesting extra energy from the turbine, OR, used like a supercharger to drive the compressor)
• 3: Pair of MGUs on the front wheels acting as KERS, as allowed in the ACO rules.

If I read the rules correctly, then having both #1 and #3 is not allowed, you could only have one or the other (KERS acting on either the front wheels or the rear wheels, not both). I have no idea how #2 would fit in with the rules, or even if it is legal.

Another idea to consider is running the engine water cooling loop, after passing through the engine, through a heat exchanger surrounding the exhaust (aft of the turbo), then sending the coolant through a turboexpander to drive another generator. I dont have the technical background to know whether that would work, and even if so, if it would pay for itself in terms of weight/complexity.

Very Nice job mate. Who is the 3d modelling program that you used?
Congratulations.

[cdsvg]

Originally Posted by gustavobamba

Very Nice job mate. Who is the 3d modelling program that you used?
Congratulations.

3ds Max. Not a proper CAD program, but it does the job.

[chernaudi]

Audi have released photos of the S6, S7, and S8 sedans, including engine shots.

Audi themselves haven't stated if the engines use the "hot side inside" concept of the R18, but the location of the intake pipes and where they feed into the airbox (especially on the S6 and S7) does suggest the use of that idea:

http://www.fourtitude.com/gallery/ga...&dispsize=1024

I believe that the 4.0T V8's use of the turbochargers mounted within the V of the engine is similar to the R18's concept aside from the fact that the R18 only uses one turbo, but it may also point toward the R18's possible utilization of a turbocharger driven or assisted hybrid system, especially if the R18's V6 is similar in size to the road going V8.

In short expect to see the same on the R18, but with two less cylinders and without the flashy plastic airbox/turbo cover.

And I do wonder if in time any link can be established between the R18 and the new turbo Audi production engines.

[Adam43]

Originally Posted by Victor_RO

Except you missed the 20-30 minutes when Lotterer was lapping in the 4:00-4:10 bracket when the track was really wet, and both Pagenaud and Davidson were in the 3:50s and sometimes 3:40s. Those minutes basically cut the leading gap in half.

I watched the race and I can vouch that this did happen! As the article says! There are reasons for this, but it did happen. The Audi wasn't slow enough for long enough to make the difference, but in the middle of those slow laps I thought they might come unstuck.

Their speed through the Porsche curves was just enough to keep them in the lead.

[gwyllion]

Originally Posted by chernaudi

Audi themselves haven't stated if the engines use the "hot side inside" concept of the R18, but the location of the intake pipes and where they feed into the airbox (especially on the S6 and S7) does suggest the use of that idea:

http://www.fourtitude.com/news/publi...cle_7153.shtml is very clear:

The turbochargers and their charge-air intercooler – an air-to-water heat exchanger – are located in the vee between the cylinder banks instead of in the more customary position on the outside of the engine block. The cylinder heads have a new, innovative layout, with the exhaust side on the inside and the intake side on the outside.

Note that Audi does not draw any connection whatsoever between the new road V8 TFSI engine and the race V6 TDI engine.

[Ferrari333SP]

Andre Lotterer was overall the best driver at Le Mans this year, imo.

[henk4]

Originally Posted by gwyllion

http://www.fourtitude.com/news/publi...cle_7153.shtml is very clear:
Note that Audi does not draw any connection whatsoever between the new road V8 TFSI engine and the race V6 TDI engine.

Porsche will use the hot-inside concept for their new 918 Hybrid road car, to keep the batteries as far away from the exhausts as possible.

[Acid09]

Originally Posted by Ferrari333SP

Andre Lotterer was overall the best driver at Le Mans this year, imo.

No, edged out by Treluyer. His stuff was magic, remember that three-wide pass with the Corvette in the sandwich?

[chernaudi]

It doesn't matter, but I feel that long term, Audi need to have them in the fold to challenge Peugeot long term on the driver front, because McNish can't keep driving forever.

[MihokS5]

Looks like the R18 has another evolution of the section where the front fender meets the nose. It looks like one smooth piece now that connects to the side pods:






http://www.endurance-info.com/versio...?page=847&np=3

[MulsanneMike]

Originally Posted by MihokS5

Looks like the R18 has another evolution of the section where the front fender meets the nose. It looks like one smooth piece now that connects to the side pods:






http://www.endurance-info.com/versio...?page=847&np=3

Yes, checking the head on angle on Endurnace Info and you can see a lot more camber towards the leading edge:

http://endurance-info.com/version2/g...Libres1_36.jpg

[MihokS5]

The #1 Audi is running the sprint nose from Monza-