Porsche back in Le Mans!

[WhiteBlue]

Privateers will have some leeway with regard to hybrid systems. For factory teams hybrid is compulsory. Privateers can race without electric systems.
It is not the pitting frequency that plays a big role that it has today. The 2014 engines will have technology specific fuel flow meters. The flow will be different for diesels and petrol and for the size of the hybrid system. You can get a bit more fuel if you choose the smallest of the four hybrid systems. You can have 2,4,6 and 8 MJ electric systems and you can have them on front and rear wheels.
I reckon that the 4 and 6 MJ systems will be the most popular. Electric front wheel drive will give you superior traction while electric rear wheel drive will eliminate the turbo lag and give you good acceleration. You could see the benefits on the Toyota and the Audi last year. Only then they had only one hybrid system and had to make a choice where to put it. So IMO they probably will all be using AWD.
I'm not sure if electric compounding will be very popular. For LMP1 it will be legal but not mandatory as in F1.
The one thing I'm confident of is the effect that 30% reduced fuel flow will have on the engine format. Only dowsized turbos will be the correct answer to that challenge. The big volume multi cylinder NA engines will bite the dust. Even a moderately blown V8 will simply have too much friction from all these moving parts. Small turbos will run on relative low rpms and with much fewer moving parts. That will do the trick.

[xpensive]

But at the end of the day, it will still be up to the engine if you need this certain fuel-flow, it is a maximum, isn't it?

Le Mans was never a sprint race, unless you are Dan Gurney, and perhaps the given flow will be enough for a V8?

How many g/s are we talking anyway?

[WhiteBlue]

I think it is provisionally expressed in L/lap. The actual flow rates will be adjusted when they can test the different cars. But petrol rates will be higher than diesel. I will have a look at the old thread to find out the provisional numbers.

[xpensive]

In that case, I cannot see that Porsche will tie a rope around their neck with a V8, at least not for 2014.

[WhiteBlue]

http://www.autoblog.com/2012/06/17/le-m ... tions-eas/

A fuel meter will allow a diesel-powered car 3.99 liters per lap, a gas-powered car would get 4.95 liters per lap, from tanks that are about 12 percent smaller.

http://www.bosch-motorsport.de/content/ ... E_0213.pdf

In the draft regulations of August 2012, the ACO stated a maximum fuel flow of 34.4ml/sec.

AFAIK this relates to the 4.95 L/lap allowed for the petrol engines without hybrid systems. Such systems are only for privateers. I need to research how the size of the hybrid system will reduce the fuel flow.

http://www.lemans.org/wpphpFichiers/1/1 ... n_2014.pdf spezifies:
petrol consumption
2012 estimated 6,13L/lap
2014 consumption targeted
privaters without KERS 4,95 L/lap = 34.4 ml/s
factory 2MJ KERS 4,8 L/lap = 33.4 ml/s
factory 4 MJ KERS 4,65 L/lap = 32.3 ml/s
factory 6 MJ KERS 4,50 L/lap = 31.3 ml/s
factory 8 MJ KERS 4,42 L/lap = 30.3 ml/s
So a 2014 factory petrol car with 6 MJ KERS system would have 27% less fuel flow than it had effectively in 2012.
That comes very close to the fuel saving F1 is supposed to have in 2014. Hence my impression that we will have similar efficiency requirements.
The Bosch source that simulated various engines and flow rates concludes:

An increase of 5 per cent engine efficiency will lead to a reduction in lap time of more than 3 seconds, whereas an increase in downforce of 5 per cent brings only 0.42 seconds. There will be a huge shift to the development of engine efficiency and drag reduction, two areas where the public can profit fromthe factory’s racing efforts.

[xpensive]

34.4 cc/s of gasoline, a strange number indeed, relates to 1180 kW input, 34% efficiency means 400 kW or 550 Hp.

Still more the the 917 ever had in 1971.

[WhiteBlue]

The engine efficiency will be the big target everybody will be developing towards. They will have all the goodies like variable geometries and variable valves. So efficiency will be better than F1 I assume. I would not be surprised to see LMP1 engines with 3-4% different engine efficiencies between privateers and factories. The factories can afford to pump a lot of money into things that will go 1:1 into their road cars.

[xpensive]

But the running point is still; will there be a limit as to how much fuel you can take on during pit-stops?

[TzeiTzei]

You can get a bit more fuel if you choose the smallest of the four hybrid systems. You can have 2,4,6 and 8 MJ electric systems and you can have them on front and rear wheels.
I reckon that the 4 and 6 MJ systems will be the most popular.

Bart Hayden from Rebellion was interviewed just recently about their 2014 car. He said that only the most powerful electric system would make sense from performance point of view. He ofcourse might have his reasons to say that, because Rebellion wont be using (cant afford?) hybrids next year.

[WhiteBlue]

But the running point is still; will there be a limit as to how much fuel you can take on during pit-stops?

That is one aspect of Le Mans racing that will not change. Apparently the diesels will have smaller fuel tanks than the petrol fuelled car.

You can get a bit more fuel if you choose the smallest of the four hybrid systems. You can have 2,4,6 and 8 MJ electric systems and you can have them on front and rear wheels.
I reckon that the 4 and 6 MJ systems will be the most popular.

Bart Hayden from Rebellion was interviewed just recently about their 2014 car. He said that only the most powerful electric system would make sense from performance point of view. He ofcourse might have his reasons to say that, because Rebellion wont be using (cant afford?) hybrids next year.

That would support my theory that AWD with a big KERS system will be the best performance choice.

[xpensive]

So, what are you saying here WB, regardless of everything you can still fill up as often and as much as you like?

In that case, I'll go with the twin turbo V8 any day of the week.

[WhiteBlue]

As far as I can say the cars will have fuel flow sensors that will restrict the fuel flow and limited capacity fuel tanks. But they will be able to refuel as often as they want. But I think that the fuel flow restriction will restrict the performance of big engines.

[xpensive]

But flow-limit is per time unit, not over one lap, different things that. The efficiency advantage of an I4 will be at peak-power, where my twin turbo V8 can afford do shed a few Hp, as long as I can waste 34.4 cc/s with grunt the rest of the lap and take an xtra long pit stop to compensate.

[WhiteBlue]

I do not understand your reasoning. If the small turbo is more efficient it will simply make more hp out of the limited fuel supply. Both engines will have the same fuel flow available. And if the 4-cylinder makes more power the car will have higher performance. How will you escape from that dilemma? Higher performance and potentially shorter refuelling stops will all favour the more efficient engine, which is not likely to be your V8.

[Pierce89]

I do not understand your reasoning. If the small turbo is more efficient it will simply make more hp out of the limited fuel supply. Both engines will have the same fuel flow available. And if the 4-cylinder makes more power the car will have higher performance. How will you escape from that dilemma? Higher performance and potentially shorter refuelling stops will all favour the more efficient engine, which is not likely to be your V8.

There's always the chance larger motors will be more efficient from revving much lower and creating less friction, but obviously more cylinders will create more friction so its a trade off. Nothing that couldn't be sussed out with a spreadsheet.