WEC (World Endurance Championship) 2014

[machin]

Well, I've had a go and putting some figures to the "unknown" values:-

Figures in black are directly from the latest FIA Appendix B.
Figure in blue are estimated figures
Figures in red are calculated using the black and blue figures.



Some general observations:-

Using these figures the Kinetic energy per lap and max no. of laps at full power for a non ERS car is the same regardless of whether the main engine is diesel or petrol.

The Kinetic energy per lap and max. no of laps at full power for an 8MJ car is the same regardless of whether the main engine is diesel or petrol.

An 8MJ Hybrid car gets approximately 3% more kinetic energy per lap than a 2MJ car, i.e. (contrary to my previous belief); a bigger Hybrid system car does get a slight advantage in lap time, and not just in stint length compared to a car with a smaller hybrid system.

At a little less than full power an 8MJ car should be able to do 1 more lap (at Le Mans) than a 2MJ car (15 laps vs 14 laps), regardless of whether the main engine is diesel or petrol.

For a 2MJ Diesel to do a 15 lap stint it would need to run at approx. 92% of its maximum allowed fuel flow per lap (i.e. 92% of its maximum allowed average power).

[Cold Fussion]

Well, I've had a go and putting some figures to the "unknown" values:-

Figures in black are directly from the latest FIA Appendix B.
Figure in blue are estimated figures
Figures in red are calculated using the black and blue figures.

http://i90.photobucket.com/albums/k248/ ... 33776c.jpg

Some general observations:-

Using these figures the Kinetic energy per lap and max no. of laps at full power for a non ERS car is the same regardless of whether the main engine is diesel or petrol.

The Kinetic energy per lap and max. no of laps at full power for an 8MJ car is the same regardless of whether the main engine is diesel or petrol.

An 8MJ Hybrid car gets approximately 3% more kinetic energy per lap than a 2MJ car, i.e. (contrary to my previous belief); a bigger Hybrid system car does get a slight advantage in lap time, and not just in stint length compared to a car with a smaller hybrid system.

At a little less than full power an 8MJ car should be able to do 1 more lap (at Le Mans) than a 2MJ car (15 laps vs 14 laps), regardless of whether the main engine is diesel or petrol.

For a 2MJ Diesel to do a 15 lap stint it would need to run at approx. 92% of its maximum allowed fuel flow per lap (i.e. 92% of its maximum allowed average power).

Interesting numbers. When you say per lap, I assume that is for a lap of Le Mans? If so that means the 8 MJ class saves 2 extra stops when running on full power compared to the 2 MJ class, which amounts to something in the realm of 100s. Audi must think that their packaging issue costs more than half a lap of Le Mans. Perhaps this is a throwback to the 2011 R18 being originally designed without the hybrid stuff in mind, which is now costing them. it does seem strange that Audi would throw away all that extra energy, especially when considering their original decision to go with a diesel in the first place with the R10.

[machin]

When you say per lap, I assume that is for a lap of Le Mans?

Yeah, sorry, that table is the EOT for Le Mans.

There could be two simple reasons why Audi were stuck with 2MJ and Porsche/Toyota have 6MJ:

1, The chassis of the Porsche/Toyota are lighter than the Audi, thereby allowing them to utilise more Hybrid tech without going over the minimum weight.
2, The Hybrid tech of the Porsche/Toyota are lighter than the Audi's thereby allowing them to utilise more of it.

It is worth noting that the respective weights of the best Diesel and best Petrol engine assemblies are supposedly (according to the FIA) equalised using the "K factor", so the bigger diesel engine weight shouldn't be the reason for the lower Hybridisation on the Audi.... although I don't see how this works myself since the K-factor only affects the per lap fuel energy allowance (note that a 2MJ Diesel is allowed more energy per lap than a 2MJ Petrol), and has no effect on the total fuel allowance (fuel tank capacity). To my mind we have a third option:

3, The Audi's Diesel engine weighs more than the Porsche/Toyota petrol engines, thereby meaning that the Audi may not be able to have as much Hybrid Tech whilst meeting the minimum weight target.

As a slight aside... assuming that all cars run at the minimum weight limit, after a pit stop the Petrol cars will be about 7kg heavier than the Diesels due to their higher fuel mass.... it may be that the FIA has determined that this offsets the best Diesel Vs best petrol engine weight assemblies... although it seems a little light to me...

[Tommy Cookers]

@ machin
does the petrol contain some very large amount of bio-ethanol or similar ?

[Cold Fussion]

3, The Audi's Diesel engine weighs more than the Porsche/Toyota petrol engines, thereby meaning that the Audi may not be able to have as much Hybrid Tech whilst meeting the minimum weight target.

I think this is likely given the fact that it is a diesel, and that historically, Audi have had fairly heavy engines (when looking back to the R10 etc). It still seems surprising that Audi would be unable to meet the 870kg limit with a larger hybrid system though.

[Callum]

Hi Machin, thanks for putting in the work. Very interesting.

[machin]

does the petrol contain some very large amount of bio-ethanol or similar ?

The petrol is an E20 and the diesel a B10. The calorific values are taken straight from the draft version of the regulations (absent from the final version).. so may not be quite right, but should be close enough for comparsion purposes.

[WhiteBlue]

All three manufacturers run different hybrid storage solutions. Toyota uses supercaps which are very light, recharge very quickly and discharge again very quickly. Audi was set to use One Williams kinetic system plus an H-type recovery but they ditched it at the last moment and so they have a very small kinetic system only which makes them uncompetitive I guess. Porsche uses a an H and a K type system with usual battery storage and four wheel drive. Theoretically they should be competitive with Toyota. While Toyota should have the upper hand on the recovery system the V4 engine of Porsche should theoretically be more fuel efficient. At the moment Porsche do not suffer from a lack of performance as Audi does but from reliability problems of a very complex system. Toyota have made it very simple and kept much of the same spec they had the years before. That could still give them the edge when we come to LeMans next time in the WEC.

[AnthonyG]

What system is the rebellion running? (same as toyota?)

[machin]

What system is the rebellion running? (same as toyota?)

They're running a Toyota V8, but none of the Hybrid systems.

[Lycoming]

As I understand, the Rebellion engine is not as... "potent" as the engine used by the Toyota works cars, can anybody confirm that?

[p___mill]

Machin,

Thanks for the great analysis of the WEC equivalency table, that really helps with interpreting the numbers.

An 8MJ Hybrid car gets approximately 3% more kinetic energy per lap than a 2MJ car, i.e. (contrary to my previous belief); a bigger Hybrid system car does get a slight advantage in lap time, and not just in stint length compared to a car with a smaller hybrid system.

I think this is precisely what has upset Audi and caught them off guard. The spread on fuel energy per lap between the 2MJ and 8MJ classes was greater before the prologue test. It was only after the test and after Audi had been homologated at 2MJ that it was changed to give the more speed to the higher hybrid usages. I think they could have easily run a 4MJ system, but their testing under the old formula showed 2MJ would be better.

The scaling of the energy allowances per lap is also interesting because it is the ratio of track lengths x 1.55 for electrical power but only x 1.11 for fuel. The shorter the track, the more power an 6MJ car will have compared to a 2MJ car. So Audi, with greater reliance on fuel power, should have a little more pace at Le Mans.

[Kiril Varbanov]

24 HOURS OF LE MANS 2014 - EPISODE 08 - AERODYNAMIQUE:

[machin]

The scaling of the energy allowances per lap is also interesting because it is the ratio of track lengths x 1.55 for electrical power but only x 1.11 for fuel. The shorter the track, the more power an 6MJ car will have compared to a 2MJ car. So Audi, with greater reliance on fuel power, should have a little more pace at Le Mans.

You are absolutely right... I've made these charts to see that effect;



I think this is slightly odd.... Why "promote" (i.e give a bigger advantage to) the bigger Hybrid cars in the WEC, but not at Le Mans?

[p___mill]

Thanks again for running the numbers. I expected there to be less of a speed disadvantage, not an advantage at Le Mans. Was that scaling factor in the rules pre-homologation? If so it could be what lead Audi to choose the 2MJ option in spite of the rest of the championship.