Audi LMP1 Discussion

[TF110]

Originally Posted by MyNameIsNigel

I assume you are referring to the better fuel efficiency of diesel engines compared to petrol engines.

It's a fact that diesel engines are more efficient than petrol engines, and this is likely going to remain the case for some time. As you know, the better efficiency of diesel is already accounted for in the EoT through the FTF of 1.077, which - expressed differently - means that the current EoT is based on the assumption that the ratio of diesel efficiency over petrol efficiency is 107.7%. In that respect, the current regulations already compensate for the better efficiency of diesel by allocating comparatively less diesel fuel energy per lap.

The (assumed or actual) fuel efficiency as such has no bearing on the ERS incentive and how it is supposed to be reflected in the relevant fuel energy allocations for each ERS class. The same fuel efficiency hypotheses should apply irrespective of the ERS class. If not, then the same principles should apply for both fuel classes. There is no reason to "favor" one fuel class over another.

Again, there is no objective justification that would explain why a greater incentive is provided in the case of the 8MJ ERS option in the petrol class and why no similar incentive is reflected in the case of diesel.

Arguably, in the case of diesel, a similar incentive should probably be reflected not only in respect of the 8MJ ERS option, but already in respect of the 6MJ ERS option, taking into account the overweight of diesel powertrains.

107.7%? So 41% petrol vs 44% diesel. I think thats a bit on the optimistic side to expect a petrol engine to reach that, especially in a race engine! All this tech talk is irrelevant for now until they change the incentive or the regulations altogether. I guess we will see after LM.

[MulsanneMike]

Originally Posted by chernaudi

Getting back to Audi rumors, Mulsanne Mike on his FB page has heard a rumor that Audi tested something related to the R18 recently in the Wind Shear wind tunnel in Charlotte, NC

Wind Shear, of course, is the wind tunnel that Gene Haas and Haas CNC opened a few years ago that has a 180+mph rolling road among other features. Thus, though it's ownership by Haas CNC and association with Stewart/Haas Racing and Haas CNC and it's use by various NASCAR teams and other NA racing teams and series, it's fairly well known in motorsports.

Just about everyone and their brother use Wind Shear, it's not just a North American thing. F1, WEC, OEMs, everyone comes and uses Wind Shear at it's really the only one of its kind. At least the only commercially available one of its kind to my knowledge. That Audi is there should be of no surprise and it certainly isn't their first time I can assure you.

[MyNameIsNigel]

Originally Posted by TF110

107.7%? So 41% petrol vs 44% diesel. I think thats a bit on the optimistic side to expect a petrol engine to reach that, especially in a race engine! All this tech talk is irrelevant for now until they change the incentive or the regulations altogether. I guess we will see after LM.

You will recall that Toyota did claim in a presentation made last December that they achieved "more than 40% thermal efficiency" with the 2014-iteration of their NA V8 engine. The 41% efficiency hypothesis therefore seems pretty realistic.

[TF110]

Originally Posted by MyNameIsNigel

You will recall that Toyota did claim in a presentation made last December that they achieved "more than 40% thermal efficiency" with the 2014-iteration of their NA V8 engine. The 41% efficiency hypothesis therefore seems pretty realistic.

You sure? I think the efficiency claim is engine combined with their hybrid system. Diesel on its own without a hybrid can reach 44%+. Toyota claims the same for the Prius but includes the hybrid.

[cokata]

41% efficiency on it's own is not mega impressive, since there are production engines with 39%+. What is more impressive are talking about 41% at 7000+rpm (i believe), since it won't do them any good if it is bellow that.

[GasperG]

Over 40% efficiency is claimed on the engine alone, Prius is claimed to be 38% efficient on the engine alone (220 g/kWh).

[TF110]

Toyota claims non-hybrid engines are around 36%. But theyre claiming 38% (currently) and above 40% for hybrids http://www.greencarcongress.com/2014...620-estec.html. If any petrol team is above 41% without the hybrid, thats amazing.

[GasperG]

Again, this ICE efficiency only, believe it or not.

And don't forget that teams are playing with high grade fuels here, probably easier to achive higher efficiency, but problem becomes peak power/peak efficiency. This IMO is directly colerated with engine weight and this brings us to Audi, where it seems the power is the main engine weight problem, not efficiency.

[chernaudi]

Audi rumor: It's been said that they're aiming for 4MJ, which can be easily done by reverting back to the 2012/13 spec flywheel and upping the juice until it's up to 4MJ instead of 3.5. But those who have attended tests where an alleged 2015 spec car was running have stated that the 2015 car sounds a lot different than the 2014 cars did. That hints at least to something like Audi adopting a Toyota/Porsche-like periscope exhaust system. But some have also started rumors that Audi may be running a second hybrid energy capturing system, similar to turbocharger compounding or the Porsche take on the ERS-H system. And that would suggest IMO that Audi might be aiming at 6MJ vs 4MJ if that's the case. And of course, no photos have surfaced as of yet, and we probably have a while to wait (probably when they show up at Sebring at the end of the month) for anything to come out.

[TF110]

Theyd gain too little with an ers-h system to reach 6mj. By their own admission, correct?

[Articus]

Originally Posted by TF110

Theyd gain too little with an ers-h system to reach 6mj. By their own admission, correct?

I'm pretty sure they said something to that effect last year. But again that was last year. I think a 6MJ Audi is the only shot they have at being on equal footing. With Toyota and Porsche rumoured going 8MJ, if Audi goes to 4, it will be only slightly better than last year.

[cokata]

Originally Posted by Articus

I'm pretty sure they said something to that effect last year. But again that was last year. I think a 6MJ Audi is the only shot they have at being on equal footing. With Toyota and Porsche rumoured going 8MJ, if Audi goes to 4, it will be only slightly better than last year.

Let's say they can achieve 6mj. They would need either both axels to recover energy (like the toyota) or to have ERS-H. And since ERS-H would be lighter and they have already played with it, it would make sense to chose it as an option.

But with the way the rules are ATM, they would have greatly reduced fuel flow and when you add in the negative impact of ERS-H on efficiency and you end up with reduced engine power. No matter how good audi are ICE is a very mature technology and you just can't make such a massive jump in efficiency in just an year.

Audi have always made their cars for Le Mans only, they don't really care for anything else, and at Le Mans the smaller MJ classes are competitive, when you add in the reliability factor i can say that it is a pretty safe bet that they will go to 4MJ, not more.

[MyNameIsNigel]

Originally Posted by TF110

Theyd gain too little with an ers-h system to reach 6mj. By their own admission, correct?

Well, Porsche do manage to reach 6MJ thanks to a combined ERS-K and wastegate-type ERS-H, don't they ? The addition of an ERS-H inspired on Porsche's solution may therefore be of significant value to reach that target (in theory at least).

Now, Audi have all but confirmed that they are going to make the jump to 4MJ this year (based on Dr. Ullrich's rather explicit admissions as reported recently by AutoHebdo). The limiting factor still appears to be limited energy storage capacity, not so much the ability to harvest energy. It would be surprising if Audi ultimately find a way to double that step (unless they change their ES solution).

A switch to 4MJ may however be sufficient IF this is accompanied by reasonable improvements of the engine's thermal efficiency. Let's not forget that the current EoT is based on 2014 efficiency targets/hypotheses and that a substantial part of the allocated energy still comes from burning the fuel energy allocation (approx. 60 MJ/lap at LM if one assumes a 2014 efficiency target of the order of 44%).

Further improvements on the engine side, bringing the engine's thermal efficiency up to e.g. 46% (i.e. an improvement of less than 5% compared to the 2014 target - which appears to be reasonable IMHO) would translate into a gain of more than 2 MJ/lap. That would compensate for the inability to run in the 6MJ ERS class.

[TF110]

Audi are not Porsche, though. I think the limiting factor is their flywheel and their choice of engine/size. If theyre able to drop some weight elsewhere, they should be ok with more hybrid power. But then the Toyota squad theorized Audi dropped the ers-h because it robbed the engine of efficiency. But what were Audi's words, it wasn't even there to increase recovered energy?

[Articus]

Originally Posted by TF110

Audi are not Porsche, though.

[MyNameIsNigel]

Originally Posted by TF110

But what were Audi's words, it wasn't even there to increase recovered energy?

According to Audi's most recent statements, the system they tested last year was indeed not supposed to harvest energy, but rather intended to be used as anti-lag system. Strictly speaking, that would suggest something different than an ERS-H, a concept probably similar to the electrical compressor system showcased on the 2014 Audi RS5 TDI Concept that supplements a conventional turbocharger. Such a solution would be diametrically different to Porsche's solution which uses an electrical turbine exclusively for the purpose of harvesting energy.

The above solutions do not appear to be detrimental to overall efficiency. The F1-style e-turbo possibly is.

IMHO, the electrical compressor system would only make sense if Audi were to replace the current VTG system on reliabilty grounds. One advantage of the electrical compressor showcased in the Audi RS5 TDI Concept resides in the fact that the electrical compressor can be moved away from the engine and thereby be less exposed to thermal constraints.

As for a Porsche-inspired wastegate solution, Laudenbach has openly admitted that Audi were looking at similar concepts. This may end up on the R18 ultimately, but likely not on the 2015 car. More likely on the 2016 car.

[TF110]

Had a read back on racecar engineering and this is what was said on the mgu-h by Baretzky

The MGU-H is less of an influence in the design of the engine, it is more complex in terms of overall energy management in the car,’ says Baretzky. ‘You have an amount of energy then you have to use it, and if you waste it you are lost. You have to have the management to do this, part of it by the driver, and some by the electronics.

‘The engine design methodology has not changed at all because it was always part of our job to run the engine efficiently. The only thing that has changed is the proportion; only economy or only power, and it has moved more towards economy. You have less quantities of pure performance in the lap than before to take the efficiency and to use the energy, because the energy is still used by the combustion engine, and nothing else.’

The flywheel now exactly fulfils our demands, which we have for the new rules. Anything else would be stupid. It is the same principal, some components we took over. A hybrid system is a system. If you have an MGU with a max power of 170Kw, and a storage system capable of 100. You also need to work out how much storage do you need, and you don’t take more because it is weight.’

I took that as the mgu-h loss wasn't really a loss because it must have had a tradeoff.

[MyNameIsNigel]

It was reported more recently (i.e. back in September 2014) that Audi would re-evaluate a second ERS to complement the existing ERS-K and that "regeneration of exhaust gas energy" was still on the agenda. Probably not in the form that Audi tested last year, though, but more likely a solution inspired from Porsche's solution.

The key limiting factor however remains energy storage capacity. There is no point adding an ERS-H to harvest more energy if you cannot store it for subsequent release. With the existing 600kJ flywheel system, Audi are still very much limited in that respect. That would in theory be sufficient to achieve 4MJ at LM, but not 6MJ.

So, unless Audi have managed to save 50kg on the engine and found a way to increase the storage capacity of their flywheel-based unit (or opted for a different energy storage technology), I can't see how Audi could fit an additional ERS-H on their 2015 car.

The more "sensible" approach for 2015 appears to me to be a jump to 4MJ combined with optimized ERS architecture and improved engine thermal efficiency (and aerodynamic improvements).

[tomerswayler]

I think that for the lower MJ classes, energy recovery from the exhaust alone could be enough to always have the energy in the store that is needed for the acceleration zones.

During an average race lap in Le Mans, with a 50hp(36,8kW) ERS-H system for example, one can gather ~205s*36,8kW*0,7 = 5,28MJ of energy.

Any information available on how much power the Porsche system has and how many seconds it is active on average?

[gustavobamba]

With all this calculations about the best hybrid solution to Audi, I still believe they will stay in low config. 2Mj or 4Mj.

In 2014 with a LD aero config and 2Mj they manage well (Le Mans). If they improve the aero that could be enough… they only increase Mj if the weight stay´s low.

[Articus]

Maybe they will go with a certain batch of titanium connecting rods.

[chernaudi]

Who'd wanna place bets that the 2015 sprint spec Audi R18 might look a lot in concept like the 2013 sprint spec R18? It wasn't overly strong in one area, but as a package it had an excellent balance of attributes, similar to Toyota last year:









I'd rather see Audi go for matching a good balance of attributes, instead of excelling in one are to the detriment of others, which performance-wise is what happened last year.

[CTD]

Originally Posted by chernaudi

Who'd wanna place bets that the 2015 sprint spec Audi R18 might look a lot in concept like the 2013 sprint spec R18? It wasn't overly strong in one area, but as a package it had an excellent balance of attributes, similar to Toyota last year:









I'd rather see Audi go for matching a good balance of attributes, instead of excelling in one are to the detriment of others, which performance-wise is what happened last year.

Well that was went wrong with the original R15.
They designed it to be good in the ALMS as well as at Le Mans, but it only ran Sebring because of missing support from Audi NA, If I remember correctly.

[chernaudi]

Audi did design the original R15 with a bias towards the ALMS, but when it ran at LM it was hopeless because of aero drag and it wasn't really any faster than the R10 was. It won Sebring and nearly won PLM in '09, but those were at the shorter tracks that the package was designed for.

Audi struggled last year to a lesser degree for much the same reason: an aero package biased towards tracks like Silverstone, COTA and Nurburgring GP. They did well at LM in terms of speed and pace, but that was with an entirely different aero package. Hence, why I'd expect an aero package that's an intermediate between last year's sprint package and last year's LM package, something like the 2013 R18's sprint package.

Oh, and BTW, Audi, since Toyota's 2015 car got papped at Algarve the other day, can you come out and play yet?

[CTD]

Originally Posted by chernaudi

Audi did design the original R15 with a bias towards the ALMS, but when it ran at LM it was hopeless because of aero drag and it wasn't really any faster than the R10 was. It won Sebring and nearly won PLM in '09, but those were at the shorter tracks that the package was designed for.

Audi struggled last year to a lesser degree for much the same reason: an aero package biased towards tracks like Silverstone, COTA and Nurburgring GP. They did well at LM in terms of speed and pace, but that was with an entirely different aero package. Hence, why I'd expect an aero package that's an intermediate between last year's sprint package and last year's LM package, something like the 2013 R18's sprint package.

Oh, and BTW, Audi, since Toyota's 2015 car got papped at Algarve the other day, can you come out and play yet?

I missed that you were only talking about the sprint package. I though you were talking about the entire design philosophy of the car.