LM Classes, Fuel and tyre stops

[Adam43]

So how do the five classes compare? Here they are listed with the fastest time in that class

LMP900 3:30.296
LMGTP 3:34.556
LM675 3:33.414
LMGTS 3:52.070
LMGT 4:10.081

The first three could potentially be battling for overall honours this year (if the ACO have got there sums right!).

Does anyone have any idea how many laps each will have to make between stops! I have last years comprehensive results list and the data is there, but unfortunately there is at my parents! I will retrieve this next time I visit. However, if I know you lot (which I don't! ) then this information will not only be to hand, but also lodged in those sportscar brains.

The LM675 cars should be able to go longer because they are more fuel efficient. The MG went very quick, but did it close enough to the Audis to challenge?

The Bentley should be similar to the Audi in terms of the number of stops it has to do, but will it have to change tyres more often (it has narrower tyres and could well use them more). It is also quite a bit slower.

How much will last years race be a guide? How much has changed.

So what we need to know:

How many laps between stops?
How often will the tyres need to be changed?
How many stints will each driver do?
How relevant are the times in comparing the cars performance?

[Nordic]

I don't think last years results are going to help much due to the monsoon,
Over a single lap the 675's may nearly be a match for the 900's and for the first hour or two may even be challangeing for the lead. But once the first couple of stops are complete, then I would expect the faster 900's to be way down the road.
I think the Bentley will strugle and will be dicing with the MG's due to its smaller tyres.
The GT & GTS cars seem to have quite a bit of space between them in terms of lap time.

[Adam43]

Originally posted by Nordic
I don't think last years results are going to help much due to the monsoon,

I think you're right.

Over a single lap the 675's may nearly be a match for the 900's and for the first hour or two may even be challangeing for the lead. But once the first couple of stops are complete, then I would expect the faster 900's to be way down the road.

but if the MGs have to stop less by running a lap or two longer then this could bring them back into the equation. However I think this may only get them into the lead for a couple of laps at the first round of pitstops. By the time (If?) the Audi has had to make an extra stop to the MG will be too far back to capitalise

I think the Bentley will strugle and will be dicing with the MG's due to its smaller tyres.

I think this could be true. The Bentley should have no problem getting past the MG if it finds itself nearer, but will it have to stop more (and change tyres more)?

The GT & GTS cars seem to have quite a bit of space between them in terms of lap time.

Yeah, I just put it in for completeness. I expect some of the GT cars can go over an hour between stops.

[Fab]

Seems to me that the LMP 900 make between 12 and 15 laps between each pit stop... large gap, I know, but I don't have the information at the office as well...

The main question is the total time they pit in the race ; a lot of gap between the cars (25' to hours...). They change the tyres... when they need to ! Around each two stops, or each driver change, i think...

[Aysedasi]

I just haven't had time to go over the data in detail from 2001 Adam, but I did do quite a bit of work on the pit stops in 2000. Most of the teams seemed to run between 11 and 14 laps between stops, although the Audis were consistently managing 13-14. What was very noticeable though was just how slick the Joest stops were. 50-odd seconds for a normal fuel stop with no tyre change. The amount of time they gained actually during the pit stops would be of some significance when everything was totted up.

Some of the teams might well practice their pit stop routines before June!

[Adam43]

I remember the Joest stops being impressive too - not only the fuels stops, but they seem to change the rear end as a matter of course (like brake discs, or even tyres)!!!

I think the Joest cars had a significant advantage (even over the private Audis) in how many laps they could do. They could always go 1 or 2 laps more. Wasn't this attributed to the direct fuel injection system they had on the 2001 cars? Presumably the private Audis and the Bentley now have this..

[SL]

Looking at the 2000 yearbook tim spent in the pits
7 Audi 40 min 53 sec incl rear end change
8 Audi 31 min incl windshield replaced
9 Audi 39 min19 sec incl rear end change, diffuser and transponder

There was no equal 675 cars that year, but the 32 Lola spent 3 hr 46 min in the pit less 2h 45 for the diff change and about 20 min for later checks make pit time about the same.

I would expect the MG crews to be a little better than the Lola team in 2000 and the MG to go further and faster.

Allowing 10 sec a lap slower over 360 laps the MG would lose 1 hour, 300 laps and 50 minutes. If they are just 5 sec a lap slower then we could have a race on.

Simon

[FG1]

Originally posted by AdamAshmore
Wasn't this attributed to the direct fuel injection system they had on the 2001 cars? Presumably the private Audis and the Bentley now have this..

The 2001 Audis and the new Bentley engine are both direct injection. It will be interesting to see what the Bentley's fuel consumption will be.

FG

[Adam43]

Originally posted by FG1
The 2001 Audis and the new Bentley engine are both direct injection. It will be interesting to see what the Bentley's fuel consumption will be.

It will depend on what effect the different air restrictors have, and the effeciency of the Bentley's shape.

Of course it could all be complicated further, by different gearbox ratios, rev limits, etc...