[LMS] Audi R18 (including Cake Analysis)

[vyselegend]

Originally Posted by chernaudi

It could also be for the rumored KERS system, but wouldn't Audi go for the Peugeot automatic system or one with a simple push button (or both types of actuation) instead of paddles to operate it?

I believe the ACO has enforced that KERS must be continuously coupled to the throttle (no push to pass allowed), so it's not only Peugeot, but everyone running a KERS who must run it in "automatic" release mode. However I wonder to which degree they might be allowed to manage it. I suppose they can at least desactivate it if it's malfunctioning, or possibly make it release more or less power according to engine mapping (as part of the engine map program?)

I'm also impressed at the lap times of the R18 in the test. Did any speed trap figures get published? Maybe the single RW pillar setup is worth a few km/h in drag reduction.

At the Peugeot launch Famin said they hadn't had this solution on their car only because when they started its design 2011 rules were stating that two RW supports were mandatory. However he minimised the impact of it on overall performance (litteraly he said: "It won't prevent me from sleeping"). But he looked a bit tired, didn't he?

[gwyllion]

Originally Posted by chernaudi

And ASR doesn't work efficently on diesels because diesels don't have spark plugs to cut out, so a driver adjustable system to cut or boost power and torque to the driving wheels maybe just as if not more effective, whether or not teamed with ASR.

Please provide a source for this claim. Intuitively I would think that traction control is just a matter of cutting the piezoelectric injectors from injecting diesel in the engine. I don't see why this would be difficult.

Diesel powered road cars have all the electronic driving assist mechanisms (ASR, ESP, ...).

Originally Posted by chernaudi

It could also be for the rumored KERS system, but wouldn't Audi go for the Peugeot automatic system or one with a simple push button (or both types of actuation) instead of paddles to operate it?

As vyselegend pointed, the ACO rules explicitely state

The combustion engine and the electric motor must be controlled by the driver using the accelerator pedal (push to pass buttons forbidden).

I would say hand clutch (like in F1). Last year TK had issues with the foot clutch after his injury.

[gwyllion]

Originally Posted by gwyllion

Please provide a source for this claim. Intuitively I would think that traction control is just a matter of cutting the piezoelectric injectors from injecting diesel in the engine. I don't see why this would be difficult.

Diesel powered road cars have all the electronic driving assist mechanisms (ASR, ESP, ...).

BTW on http://www.totalmotorsport.com/Featu...play.asp?ID=29 you can see that even the old R10 had a dial with 9 positions for ASR/traction control.

Originally Posted by chernaudi

we know how in the race the R15s at times hassled the new 908s, which may've been holding back slightly, but like in F1, I don't think that you can make up nearly a second without some moderatly major upgrades because of how close things are now.

I would classify the new aero package that Peugeot tested in Monza, as a rather substantial change. Moreover, in the Monza test video the engine sounded different than in Sebring. So on the engine front Peugeot is also making changes.

[chernaudi]

I just hope that Peugeot isn't pushing the evelope too far like last year when a last minute change cost them. However, for Audi to be about a second faster at Sebring (a sprint race track) with a low downforce setup compared to Peugeot (who were ultimately running about 90-95% max downforce) doesn't bode well for non-LM ILMC events unless Peugeot have something in reserve, as I doubt that the new bodywork will have much use outside of LM.

Of course, we don't know if Audi are done testing the R18 (obviously they're not, but we don't know if they're done fine tuning it, which they most likely have more they'd like to do). Of course, the test at Sebring was done mostly to prove mechanical reliablity and dial in the mechanical set up. I don't think that they learned much from an aero standpoint (at least for prolonged straightline blasts like at Le Mans). So I'd expect them to test at Monza and EuroSpeedway's oval like last year. I'd also think that most of their testing at Homestead was on the 1.5 mile NASCAR oval.

Peugeot have almost a new car for LM from Sebring (almost every body panel has changed, with only the tub, suspension and basic powertrain remaining the same), and I wonder if Audi may massage more changes into the R18's LM bodywork. Although, as vyselegend said, we don't really have any data about the R18's trap speeds, though obvously for it to be about 1.5 seconds faster than the equivalent R15 (which has about 550 bhp and the Pugs weren't really any faster down the straights), it has to have more power (which Baretzky claims) and less drag (closed cockpit and not running a high downforce package as far as I know yet), and the wider tires and better optimized suspension (reduced zero keel=lower front CG?) means more grip and better braking.

Pretty much confirms what Allan says, that it's a little better in almost every area, and I'm surprised that Allan says that visibility from the car isn't that bad.

[gwyllion]

Originally Posted by chernaudi

I just hope that Peugeot isn't pushing the evelope too far like last year when a last minute change cost them.

Are you suggesting that low drag aero package is a last minute change? Yes, some of the changes are inspired by the R18, but there are a lot of preparation time before Le Mans.

Originally Posted by chernaudi

I doubt that the new bodywork will have much use outside of LM.

A lot of the new aero elements can also be used in a high downforce configuration: lower wing position, bigger end plates, NACA ducts for rear brakes, lower rear body work, new front dive plane solution, bigger head lights, ...

[gwyllion]

[chernaudi]

Rhetorical question: If so, why didn't Peugeot run the new bodywork at Sebring? After all, Sebring is a high downforce track, and I certianly don't think that the nose would be used outside of Le Mans. And if the tests at Paul Ricard were with the LM bodywork, it certianly could've been used, at least if logicistics issues didn't cause problems.

We also have to remember how much Highcroft stuggled in the ALMS last year when they ran their LM aero package in the hopes that it'd help them in traffic with higher straightline speeds. Didn't really pan out, as it at times made the car undriveable, meaning that compormises made for LM don't neccesarily work elsewhere (though Strakka ran a similar setup everywhere and didn't have such issues).

If such things would make for an improvment across the board, why waste 6 months with their Sebring spec cars? After all, the R15 taught us that it's easier to add downforce to a slippery car than to take downforce/drag off a car built for downforce circuits. Of course, much of this is rhetorical and academic, but whey not fight and wring out every advantage you can find when you know how to make them?

And if the R18 is faster in deed than the sprint spec 908 (a possibility, though by now much isn't entirely clear, as Peugeot may've been sandbagging a tad), it's probably not by a huge gap in one area. It's probably by little gains in multiple areas. Peugeot's big advantage over anything that Audi has had in recent years has been straightline speed, partly down to power, and partly due to the closed car. Now that Audi has a closed car and new regs that favor smaller capacity/less powerful engines are in effect, it'll be interesting to see how much Audi has closed the gap or gained the inititive and how they've done it.

However, if we go back to the R15 (which it's claimed that the R18 was about 1.5 second faster than on a flying lap), it's partly down to the tires, improved aero, and having an engine built to the new regs. Little differences in multiple areas that can add up to a lot. However, as we've seen in F1, which is now a sport that's decided by fractions of a second, a lot of work has to be done to make even a little gain.

[JAG]

I would have thought the 908 LM is the basis for their sprint car post Le Mans.

[chernaudi]

Or a hybrid specification? I can't see them using all of it due to the fact that aero considerations for LM and about everywhere else is different. But some of the stuff on the LM package should, at least in theory, be usable.

Which of course leads to wonder if Audi will make additonal changes to the R18 for Le Mans?

[gwyllion]

Originally Posted by chernaudi

Peugeot's big advantage over anything that Audi has had in recent years has been straightline speed, partly down to power, and partly due to the closed car. Now that Audi has a closed car and new regs that favor smaller capacity/less powerful engines are in effect, it'll be interesting to see how much Audi has closed the gap or gained the inititive and how they've done it.

I doubt that Audi has closed the gap in the engine department.

The reasons that Baretzky gave regarding the choice for a V6, did not include better performance nor better efficiency than the more conventional V8 configuation. The V6 was chosen for chassis reasons (light, short, compact, short, low cfg, ...).

Originally Posted by chernaudi

Or a hybrid specification? I can't see them using all of it due to the fact that aero considerations for LM and about everywhere else is different. But some of the stuff on the LM package should, at least in theory, be usable.

Above I already have a list of elements that can easily be carried over.

BTW you still have not provide a source why ASR is more difficult with diesel engines.

[MihokS5]

Gwyllion, you don't think that there is a chance Audi's engine will be just as powerful as Peugeots? I know it seems impossible with a V6 and a single turbo but you never know I guess...

[chernaudi]

Baretzky said that the R18's engine is making more power than the R15's performance ballanced engine, and we know that Peugeot commented at Sebring (on the race highlights broadcast) that the R15 was making plenty of power down the straights, enough that the Pug's best hope for a pass attempt was to get on the R15's tail and try for a slingshot/drafting pass.

Either Peugeot was sandbagging in their engine department (reliability or posturing?), or with the current regs, they've lost a bit of their edge, or Audi may have the better aero and/or chassis (on the R18).

However, the biggest thing that Peugeot said about the Audi R15's straightline speeds at Sebring wasn't so much top end (where the cars seemed to be equal), but under accelleration. And that's down, at least from what I've seen, to the R15 having a slight torque advantage, or the R15's VTG turbos, and obviously, Audi have invested in 1-2 VTGs for the R18's V6.

That makes me wonder if it's down to the turbos, and if it is I'd have to say that I'd be shocked that Peugeot hasn't adopted VTGs if they haven't (the fairly small size of the Pug's turbos has been referenced), since the principal is now proven and that Audi and Peugeot share Garrett/Honeywell as turbocharger suppliers.

And for the ASR, that's the only legal form of TC legal under ACO/IMSA rules. And ASR is governed by sensors that track the wheel or axle, which cut power. Which is fine on gasoline engines, as they have spark plugs--pretty simple.

Things aren't as easy on diesel engines, as the only way to cut power is, as you've suggested, cutting the injectors. However, I don't know if it's any more effective than killing spark plugs/coils. Part of the reason why Audi didn't run ASR on the R10 in most of '06 was because of reliability reasons and that it took them forever to get it to work in the first place, and Audi has made ASR systems for gasoline engines for years, though it was often teamed with ESP (which is currently illegal under the present regs).

[gwyllion]

Originally Posted by MihokS5

Gwyllion, you don't think that there is a chance Audi's engine will be just as powerful as Peugeots? I know it seems impossible with a V6 and a single turbo but you never know I guess...

Other persons on this forum like knighy are in a better position to answer this question.

I can only give a comment from Baretzky in 2005:

So why did you choose 12 cylinders? (perhaps the first question should have been – Why did you choose to build a diesel? – but we’ll get to that answer in due course)

“We carried out a feasibility study with 10 and 12 cylinder engines. Because the combustion pressures are so high, it is better to distribute those pressures across 12 cylinders rather than eight or ten.”

Ulrich Baretzky mentioned a figure for the pressures within a production diesel of 160 bar, “but we are far beyond that with the R10.”

source: http://archive.dailysportscar.com/su...rs/audir10.htm

I don't see why this rule would no longer hold.

As I mentioned in the 908 topic, the V12 TDI produced around 60 bhp per cilinder. Audi's V6 TDI has to make more than 90 bhp per cilinder, whereas Peugeot's V8 HDI only around 70 bhp per cilinder. This signifies that the Peugeot engine will have more manageable combustion pressures and temperatures.

[gwyllion]

Originally Posted by chernaudi

Things aren't as easy on diesel engines, as the only way to cut power is, as you've suggested, cutting the injectors. However, I don't know if it's any more effective than killing spark plugs/coils.

No diesel is injected and hence no combustion can take place.

With a petrol engine, no spark is given and hence the fuel that has been injected, will not burn in the combustion chamber.

Both techniques have the same effect: engine combustion and hence power delivery to the wheels is interrupted.

Originally Posted by chernaudi

Part of the reason why Audi didn't run ASR on the R10 in most of '06 was because of reliability reasons and that it took them forever to get it to work in the first place.

So Audi toke things safe in the first year, where it did not have any real competition. That does not mean that much. Peugeot has had ASR since the beginning.

BTW in your earlier post you speculated that:

Originally Posted by chernaudi

The big rumor about the McLaren MP4-23's wheel and it's extra paddles is that they were used to increase/decrease the amount of torque/power available at the rear wheels.

According to http://www.f1technical.net/developme...fe7bb435bd8409 the system you mention, functions as follows:

The new system enables the driver to change gears and simultaneously change to a different engine mapping by pulling the paddles at the same time. Most importantly, it looks to be allowed by current regulations as these only stipulate that engine mappings can only be changed by the driver. Any automatic change acting upon a gear shift is forbidden.

The LMP rules explicitely allow traction control system operating on the engine (article 1.10.4). It is known that Audi and Peugeot limit the torque of the engine in the lower gears. Therefore there is no need for this manual engine mapping change paddle.

[chernaudi]

It was speculated that McLaren were using such a system in '08 in part because of TC being banned in F1, and that selecting engine maps would dictate the power and torque flow to the rear wheels.

Of course, with ASR being legal, Audi and Peugeot tending to have engine maps that restrict power in the lowest couple of gears (though we don't know if that's of much use now with the reduced power--if the old gearboxes can handle 700+hp and 900 ft/lbs of torque, they should easily handle the 550+hp and 600+ft/lbs of torque that the R18 and the 908 now make--Corvette's gearboxes in the GT1 cars had to deal with 650hp and 600+ft/lbs, and did so easily) should make such a system redundant on their new cars.

But if it's not for something like that, it seems that a hand clutch is an obvious choice unless forbidden by the regulations. And if that's the case, what else are they for? Redundancy for the normal paddles?