Audi LMP1 Discussion

[merlot brougham]

Originally Posted by gwyllion

Funny how Baretzky is lobbying for variable valve timing, which is only beneficial for petrol engines.

I think that you should look at it like this, he isn't so much lobbying for a technology that would help petrol engines but lobbying for more relevance to what is already on the market and proven. In the interest of promoting efficiency, which the rules makers claim they are doing.

[The Badger]

I personally would like to see Audi go back to petrol and show up some of the other manufacturers , on the same foot .

[chernaudi]

Though not really relevant to the R18 itself, Baretzky seems to be lobbying Audi and Audi Sport for the R18's successor to be a gasoline hybrid with a TFSI engine that incorporates lessons learned from the various TDI engines.

Remember, FSI is what was salvaged from the partially successful Pump Duse TDI system, so maybe Baretzky wants to see what a gasoline version of the common rail TDI system is capable of, and he seems to think that both engines have plenty of room for development.

As for the R18, Baretzky claims that it's engine, which started out weighing about as much as the R8's V8, now weighs less than that and has an improved combustion scheme. This is what I think he's arguing for with a future DFI gasoline engine, that what works to improve the diesel, can work for the gas engines.

[gwyllion]

Originally Posted by chernaudi

Though not really relevant to the R18 itself, Baretzky seems to be lobbying Audi and Audi Sport for the R18's successor to be a gasoline hybrid with a TFSI engine that incorporates lessons learned from the various TDI engines.

That is nothing new. Baretzky has always expressed his desire to build an engine according the GRE concept that he envisioned, so a 4 cilinder turbocharged direct injected petrol engine.

However, the management of the Volkswagen group allegedly has already taken the decision that Audi should stick to a diesel engine for 2014.

According to a statement of the VW supervisory board chief Ferdinand Piech, the corporate sister brands should enter into competition with different technologies. Audi will remain faithful to a diesel engine, Porsche will use a gasoline engine. So far, however, the prevailing view was that Porsche could use the flywheel storage system, that it uses in the GT sport, in the LMP1 car. Now it looks like that the apparently already made ​​distribution of tasks between Audi and Porsche provides that the Ingolstadt-based team will work with mechanical energy storage, while the Swabian manufacturer clearly focus on the electrical storage with batteries.
An indication of this scenario already existed in 2010, when the then Porsche research chairman Wolfgang Dürheimer at the ALMS race at Road Atlanta noted that the future in Le Mans would be in the battery storage.

source: http://www.sportauto.de/motorsport/2...t-4179774.html

Originally Posted by chernaudi

Remember, FSI is what was salvaged from the partially successful Pump Duse TDI system, so maybe Baretzky wants to see what a gasoline version of the common rail TDI system is capable of, and he seems to think that both engines have plenty of room for development.

That is incorrect. The R8 V8 FSI engine was equipped with common rail direct injection. The injection system was unrelated to the "unit injector" TDI technology.

The fuel pressure generated by two three-piston high-pressure pumps was limited to 110 bar and adjusted by an electronically controlled valve at each fuel rail. In order to avoid any possible bottlenecks, the first test runs were performed with an electric drive for the pumps. This step made it possible to determine the boundary conditions for the fuel system independently of the engine run. Furthermore, it was therefore possible to define the capacity of the pumps in accordance with the number of revolutions. However, the two pumps were later to be driven by the intake camshafts. As a result, the fuel mass flow of each pump had to be increased from 0.45 cm3/rev to 0.65 cm3/rev.

source: http://www.ibiblio.org/tkan/audi/1_lemans.pdf

The fuel pressure (110 bar) of the R8 FSI is fairly low by modern standards. According to http://www.bosch-motorsport.de/conte.../html/4063.htm the off-the-shelf gasoline direct injection system of Bosch Motorsport, which was pioneered in the Audi R8, now supports 200 bar. The F1 2014 engine rules allow 500 bar fuel pressure!

[chernaudi]

What are those two little pump like devices that are mounted on the engine near the back of the intake assembly and below the intake plenums? Part of the common rail system?

http://www.fourtitude.com/gallery/ga...=&dispsize=800

If the Audi FSI system was set at about 110 bar, what do the TDI race engines handle? I assume that it's higher than 110 bar.

If F1 cars under the 2013 rules are allowed 500 bar, what's the limiting factor (if any) between gasoline and diesel as far as pressure?

So it seems that if the R8 ran a gasoline common rail DFI system and the R10, R15 and R18 run diesel common rail DFI, is Baretzky arguing for a full-circle return to TFSI, even though as pointed out it's unlikely with the R18's immediate successor (built to the 2014 rules)?

[gwyllion]

Originally Posted by chernaudi

What are those two little pump like devices that are mounted on the engine near the back of the intake assembly and below the intake plenums? Part of the common rail system?

http://www.fourtitude.com/gallery/ga...=&dispsize=800

Yes, but that is a picture of Audi's road car FSI system. As you can see on this picture in the modern Bosch gasoline direct injection system, the high pressure fuel pump is driven by an additional cam on the camshaft.

The datasheet of the Bosch motorsport HDP 5 fuel pump can be downloaded at http://www.bosch-motorsport.de/en-US...2776592395.pdf

Figure 8 of http://www.ibiblio.org/tkan/audi/1_lemans.pdf shows a picture of the fuel pump of the Audi R8 race car.

Originally Posted by chernaudi

If the Audi FSI system was set at about 110 bar, what do the TDI race engines handle? I assume that it's higher than 110 bar.

According to http://issuu.com/Racecargraphic/docs/rceteh128webpub/45 the injection pressure was 2000 bar for the R10 V12 TDI and up to 2400 bar for the R15 V10 TDI.

Originally Posted by chernaudi

So it seems that if the R8 ran a gasoline common rail DFI system and the R10, R15 and R18 run diesel common rail DFI, is Baretzky arguing for a full-circle return to TFSI, even though as pointed out it's unlikely with the R18's immediate successor (built to the 2014 rules)?

I think that if Baretzky would make a new direct injected petrol engine, the injection pressure would be much higher than in the R8 days, maybe closer to the 500 bar limit of F1. Furthermore, with all the diesel knowledge the Audi and Bosch engineers could seriously improve the spray pattern of the injectors.

[gwyllion]

I am not sure if this information is correct, but according to LMR #73 the new monocoque is longer than last year.

A new monocoque – 10 cm longer - had to be built to accommodate the hybrid system in the Audi, and the German engineers had to continue the weight reduction programme already begun on the R18 with, among other refinements, the design of an innovative carbon fibre gearbox casing. This reduction was crucial to be able to carry the extra weight imposed by the hybrid system without compromising performance.

source: http://www.vif-argent.fr/lmr73/#/8/

[TF110]

But that didn't add to the length of the car did it?

[gwyllion]

The length of the car is limited to 465 cm by the rules, so it can not be changed.

I assume that this change has to do with the weight distribution of the car. The hybrid system add weight at the front, so the engine is moved 10 cm backwards as compensation.

[TF110]

I said something that was pretty plain. I meant to say would it add to the length of the cockpit, or to the front. And like you said push the engine back.

[chernaudi]

10cm=100mm or about 4 inches. We do have to remember based on Mike's estimates when the R18 came out last year that Audi did have some breathing room with the length of the car to play with as far as front and rear overhangs, and especially overall length, this being due to the fact that Audi have cut nearly 3 inches/75mm out of the wheelbase on the R18 compared to the R15's massive 3080mm, roughly what the A8L's wheelbase is for the sake of comparison as far as the R15 is concerned.

The added length is either to make more room for the electric motors, or to improve weight distribution with the electric motors and the flywheel system being mounted fore of the car's CG, which on the R18 is believed to be near or possibly slightly fore of the car's lengthwise centerline.

[TF110]

I only wondered where this length was added to. Whether it be to the front of the car or the driver area or whatever.

[MulsanneMike]

Originally Posted by chernaudi

10cm=100mm or about 4 inches. We do have to remember based on Mike's estimates when the R18 came out last year that Audi did have some breathing room with the length of the car to play with as far as front and rear overhangs, and especially overall length, this being due to the fact that Audi have cut nearly 3 inches/75mm out of the wheelbase on the R18 compared to the R15's massive 3080mm, roughly what the A8L's wheelbase is for the sake of comparison as far as the R15 is concerned.

The added length is either to make more room for the electric motors, or to improve weight distribution with the electric motors and the flywheel system being mounted fore of the car's CG, which on the R18 is believed to be near or possibly slightly fore of the car's lengthwise centerline.

For what it's worth, my estimates for both the R18 and 908 last year were wrong, significantly so. I've gone back and redone the numbers but just haven't done anything with them yet.

[gustavobamba]

Originally Posted by gwyllion

The length of the car is limited to 465 cm by the rules, so it can not be changed.

I assume that this change has to do with the weight distribution of the car. The hybrid system add weight at the front, so the engine is moved 10 cm backwards as compensation.

4650cm

[gwyllion]

Originally Posted by gustavobamba

4650cm

4650 mm = 465 cm = 46.5 dm = 4.65 m

http://en.wikipedia.org/wiki/Meter#S...forms_of_metre

[MitchZ06]

I didn't think the R18 was 46m long!

[gustavobamba]

Originally Posted by gwyllion

4650 mm = 465 cm = 46.5 dm = 4.65 m

http://en.wikipedia.org/wiki/Meter#S...forms_of_metre

you are right!!!

My son born and i´m not sleeping very well. my mistake. next time i will post my comments awake

[PaulsF1]

Is it possible, that the R18 has non adjustable anti roll bars? Neither in the technical description nor at pictures I can find any advice for adjusting the ARB.

[CTD]

Originally Posted by PaulsF1

Is it possible, that the R18 has non adjustable anti roll bars? Neither in the technical description nor at pictures I can find any advice for adjusting the ARB.

I might be wrong, but as the R18 is a closed cockpit, it doesn't have anti roll bars like an open car have?

[gwyllion]

Originally Posted by CTD

I might be wrong, but as the R18 is a closed cockpit, it doesn't have anti roll bars like an open car have?

All Audi LMP1 cars have anti-roll bars (ARB).

http://www.ultimatecarpage.com/pic/4...us-TDI_45.html and http://www.ultimatecarpage.com/pic/4...15-TDI_13.html have closeup pictures of the R15's front suspension. The ARB is clearly visible (horizontal bar under electric power steering). The R18 has an identical setup.

If I am not mistaken, you can see the rear ARB of the R15+ on http://www.ultimatecarpage.com/pic/4...us-TDI_48.html (bottom left corner).
For a picture of the R18's rear suspension see http://www.mulsannescorner.com/RCELeMans2011.html. The suspension layout looks pretty similar.

[CTD]

My bad - I'm tired - and thought of Roll Hoops

[gwyllion]

Originally Posted by kurski

Le Mans Racing Magazine (Interview) Andre Lotterer

This interview with Lotterer is well worth the read. It contains a nice anecdote about his final stint in last year's race.

Before I got into the car, Leena, our engineer, gave me the gaps and I thought we were second. When I was in the R18 the gap kept increasing, 13”, 17”, 20.” And I was driving like a lunatic asking myself how Peugeot was able to bang in times like that! I started going crazy and I took enormous risks. And on the radio I heard, ‘you’ve got to go quicker!’ It was only when I was leaving the pits for the final stint that I realised that the Peugeot was behind me. I’d done a complete stint thinking we were losing the race.

He also gives a reason why he was slow in the wet.

The rain gave me a bit of a headache as you couldn’t see very well because the windscreen misted up. I didn’t see that the track was all that wet. At one moment I was over the limit and then I couldn’t see it had dried out and I was below the limit! A prototype is really the worst car in such conditions. It’s very light from an aero point of view; it’s heavy and the speeds are very high. The grip is either on or off. I scared myself a couple of times. Lady Luck really smiled on us. It was a crazy race.

[chernaudi]

So it now seems that Andre's issue wasn't with the car itself from a handling/grip standpoint, but, like with the causes of a lot of Tom's and Allan's issues last year in traffic, he couldn't see the damp or dry parts of the track because of visibility (fogged over windshield).

Hence, he didn't know exactly when to back off and when to hammer it depending on track conditions, so he played it safe. Maybe another lesson learned by Audi after not having raced an actual closed car for over a decade?

[gwyllion]

Last year, Audi very proudly announced that the R18 was tested in their climate wind tunnel. Apparently the windscreen heating was not good enough avoid fogging.

[chernaudi]

Simulation is one thing, the real world is often another. What works in the wind tunnel might not work as planned on track is a common example of what works in theory might not be fully backed up by real word results--see the original Audi R15 or the 2011 Lotus-Renault exhaust for two examples.

Perhaps the Audi climate wind tunnel didn't account for all variables, such as temperature or to be more specific in this instance having the engine and other systems running--that can cause a heat difference between ambient in and out car temps that can cause the fogging.

That, and all wind tunnel testing is done under "optimal" conditions, which of course are weather dependent in real life, and we all know that we can't always depend on the weather forecasts...