[LM24 Race] A stint?

[Adam43]

There are a few new cars this year. Different privateers, hybrid petrols, hybrid diesels.

How many laps is everyone going to do in a stint? 10 or 11 for the diesels? What about the diesel hybrids, the petrol hybrids, or anyone else for that matter?

[Holt]

Based off of last year, the Peugeot turbo diesels used around 5.4 liters of fuel per lap, partly due to the fact the body produced less drag and downforce compared to the Audis. The Audis reportedly could run just under 12 laps, so they used just a bit more fuel then Peugeot.

So, now with a 60 liter fuel tank for 2012, and at 5.4 liters a lap, the turbo diesels could run 11 laps, but it will be close. The 908 for sure could run 11 laps with this year's regulations, but I'm not so sure about the higher downforce body of the R18, unless they've made changes to it to get less drag. I'm sure Audi has done the math, and knowing how close it will be surely they've focused on fuel economy this time around, knowing it almost let Peugeot win the race last year.

The diesel hybrids have 2 liters less fuel then the standard car, so any advantage from the hybrid has been almost eliminated.

The gasoline Hybrid of Toyota is carrying 20% more fuel then the turbo diesels. 11 laps for Toyota should be no problem at all.

So, I think all the front runners will be able to run 11 laps, but Toyota should have slightly faster pitstops as I dont think their tank will be as empty as the Audis.

[Aysedasi]

So you reckon Toyota won't run their tank dry? I appreciate the issue over time in the pits compared with extra very light running......

[GT6]

I think most of the cars will have made some effort to improve fuel consumption so perhaps 12 laps a time.

[Holt]

Originally Posted by Aysedasi

So you reckon Toyota won't run their tank dry? I appreciate the issue over time in the pits compared with extra very light running......

Well, the Toyota is a wild card. We really haven't had a competitive LMP1 gasoline car at Le Mans in....6 years? The fuel efficiency is something of an unknown with a new engine, new car, a top make, and new rules.

The big wild card for me this year is the Delta Wing. How many laps will it run? With much more efficient aero, a 75 liter tank, and a small engine that produces 200+ less horsepower then a R18, how many laps could it run? It would be something else if it could do 15 or 16 laps, or hour long runs.

[Adam43]

Originally Posted by Holt

So, I think all the front runners will be able to run 11 laps, but Toyota should have slightly faster pitstops as I dont think their tank will be as empty as the Audis.

Are the refuelling rates different for petrol and diesel?

[Aysedasi]

Originally Posted by Adam43

Are the refuelling rates different for petrol and diesel?

I believe they are, but don't know the details. One of the 'techie' members will know chapter and verse, I'm sure!

[Tim the Grey]

I'm sure there is a restrictor in the diesel filler system, to slow them down. I believe, it's so, in theory, a full tank takes as long for both.
As said though, some will still have not quite a laps worth of fuel onboard, so lose less time in fuelling to the top.
And, yes, I expect Audi to have the wick turned down, now their biggest rival has gone. Unless Toyota spring a surprise in the Ardennes...

[courageous]

Something I wonder is might a Hybrid motor allow cars to go that extra lap when before they still/only had 8/10ths of a lap worth of fuel left?

Run it until the tank is totally empty then use the battery to bring it home.

[Victor_RO]

Originally Posted by courageous

Something I wonder is might a Hybrid motor allow cars to go that extra lap when before they still/only had 8/10ths of a lap worth of fuel left?

Run it until the tank is totally empty then use the battery to bring it home.

That would mean no more "Frank Biela, what went wrong?" moments... but at the state of hybrid systems right now, I'd suspect that the last 2/10ths of the lap would still be done at a crawl and not at racing speed. Probably the perfect thing to do would be to run the thing dry exactly and precisely in the pitlane entry with the energy recovery system fully charged.

[Aysedasi]

I can hear someone at Audi saying 'We can do that' right now.......

[Steve Tarrant]

Originally Posted by Aysedasi

I can hear someone at Audi saying 'We can do that' right now.......

They can, BUT the rules were changed a while ago to state the car must be propelled by their PRIMARY power source. That's why cars aren't allowed any more to come back on their starter motor while the battery still held charge as used to be the case. Ask Olly Gavin who fell foul of this at our poste back in 2007 - he and my poste chief had an interesting discussion!!!!!

[Victor_RO]

Originally Posted by Steve Tarrant

They can, BUT the rules were changed a while ago to state the car must be propelled by their PRIMARY power source. That's why cars aren't allowed any more to come back on their starter motor while the battery still held charge as used to be the case. Ask Olly Gavin who fell foul of this at our poste back in 2007 - he and my poste chief had an interesting discussion!!!!!

Question is: did the reintroduction of hybrids to the regulations change anything in that particular rule? That's the crucial element in the puzzle at the moment. Or, if the regulations have not changed, is the hybrid system considered as part of the primary power source now? (probably a semantic difference between the hybrid system and the starter motor in the rules...)

[Steve Tarrant]

Originally Posted by Victor_RO

Question is: did the reintroduction of hybrids to the regulations change anything in that particular rule? That's the crucial element in the puzzle at the moment. Or, if the regulations have not changed, is the hybrid system considered as part of the primary power source now? (probably a semantic difference between the hybrid system and the starter motor in the rules...)

The only clear item I can see is any hybrid power (KERS, etc) can only be used if the car is already travelling in excess of 120kph.

[Victor_RO]

Originally Posted by Steve Tarrant

The only clear item I can see is any hybrid power (KERS, etc) can only be used if the car is already travelling in excess of 120kph.

From all the discussions in the technical threads, it seems as if that only applies if the KERS powers the front wheels (i.e. to the Audis).

[Gil Abobeleira]

Interesting to compare the stints of the leading cars: http://fiawec.alkamelsystems.com/Res...actice%201.PDF

The Audis (Ultra and Hybrid) were able to post some 12 lap stints (remember that last year they only ran 11 lap stints during the race).

On the other hand, the longest stint from Toyota was a 10 lap, while Rebellion were able to achieve at least one 11 lap stint.

[Adam43]

Originally Posted by Gil Abobeleira

Interesting to compare the stints of the leading cars: http://fiawec.alkamelsystems.com/Res...actice%201.PDF

The Audis (Ultra and Hybrid) were able to post some 12 lap stints (remember that last year they only ran 11 lap stints during the race).

On the other hand, the longest stint from Toyota was a 10 lap, while Rebellion were able to achieve at least one 11 lap stint.

This hints (only) that Audi has the advantage in stint length and at this stage there is no difference between hybrid and non hybrid.

[Deleted]

Petrol cars, incl Toyota have bigger tanks and fuel flow restrictors that balance things a little even if the diesels manage to make longer stints (which I don't think will be the case despite that data). This of course was never the case between Audi and Pug

[Victor_RO]

Don't know if the Toyota actually went for a good full-tank run at any point during the sessions, the stint lengths were rather inconsistent and there was only a single 10-lap run by car 7 (at least in the morning). Audi though... at least 3 12-lap stints in the morning session across the four cars.

[gwyllion]

Check again.

In the morning the #7 Toyota did a 11 lap stint (lap 8 -> 19). See http://fiawec.alkamelsystems.com/Res...actice%201.PDF

In the afternoon the #8 Toyota did a 12 lap stint (lap 4 -> 16) and a 11 lap stint (lap 16 -> 27). See http://fiawec.alkamelsystems.com/Res...actice%202.PDF

In the morning the #12 Rebellion did two 12 lap stints (lap 17 -> 29 and lap 29 -> 41) and the #13 Rebellion did one 12 lap stint (lap 25 -> 37).

[Gil Abobeleira]

You're right gwyllion, I must return to school to learn how to count

BTW, do the petrol cars have a 75 litre tank (minus 2 litres for the hybrids)?

[Articus]

Its hard to tell. There was so much gamesmanship being played. YOu get the feeling that that fuel mileage is one of the aces up there sleeves for Toyota. As well as a little more pace than we saw in the test day. People have been saying the Toyota will do 2 laps longer than the Audi. That's very believable from of experts like like Toyota.

The most important thing for a new car like their own is for it to get on track and do flawless uninterrupted stints. For the most part that's exactly what they did ignoring red and yellow flags. It was a great day for them. I think they have a lot of good data to pour over. Including exactly how much fuel was left in the tanks after each stop. Im sure they'll turn up all the dials on engine mappings, electric power etc.

[Adam43]

Originally Posted by Articus

Its hard to tell. There was so much gamesmanship being played. YOu get the feeling that that fuel mileage is one of the aces up there sleeves for Toyota. As well as a little more pace than we saw in the test day. People have been saying the Toyota will do 2 laps longer than the Audi. That's very believable from of experts like like Toyota.

Really? I am surprised by this! 2 whole laps? who are these people?

[Aysedasi]

They're here Adam - all the experts are here......

[gwyllion]

@Articus: Please provide references for your claim.

I looked at the data from the Spa and there the privateer petrol cars and Audi did similar stints. The ultra even mentioned to do one more lap on a full tank of diesel than the petrol cars.