[LM24] Technical Question about LM Gear Shift Patterns

[chernaudi]

This goes back to watching videos at Le Mans of the Audi R8 all the way though to the present day, mostly using Audi LMP cars as an example, but also comparing them to others I've seen onboards of.

Recently, I saw an Audi RS Moments of Truth video where Tom Kristensen seemed to say that in the R8 days they shifted from 4th to 5th at 250kmh, and from 5th to 6th at 280kmh. Fast forward to when the R18 came and Audi Sport reverted back to running a 6 speed gearbox. Looking at an old video from 2011, it seemed that they went from 5th to 6th at about 300kmh.

The latter shift pattern was similar to the 5 speeds used in the R10 and R15, except that 1st gear is used at Mulsanne and Arnage, instead of 2nd with the R8/R10/R15, and it seems like 6th was added as an overdrive. This on the onboards, as far as track location, I'll be using the run from Mulsanne to Indianapolis/Arnage as the example. 6th was clicked on the R8 before the first of the dogleg turns, while on the R18 it was usually either immediately after, or a few seconds later further down between the two corners.

I'm wondering what governs the shift points, especially as Porsche's onboards with their 7 speed gearboxes have them go through all their gears before that first dogleg.

Also, the R8/R10/R15 usually used 2nd in Mulsanne and Arnage, while with the R18 they almost always used 1st. Could it be traction control (something that the R8 didn't have) and the reduction in power and torque with the R18 that made using 1st in those corners feasible?

It should also be noted that during the R8/R10/R15 era, most everyone else was running a gear shift pattern at LM similar to the R18s.

[Victor_RO]

Erm... obviously engine revs? Acceleration? With the hybrid boost they get to top gear far quicker than just on engine.

[Truckosaurus]

Also, in later years they might have been working on getting better fuel economy than outright speed. And, as Victor says, I'm sure the addition of the hybrid motor would allow the use of different gear ratios, especially if they are using the electric power to do the standing starts from the pit stops.

[chernaudi]

The changes I highlighted with Audi happened in 2011, before any factory team adopted hybrids. And as I hinted, it seemed that Audi were often doing the opposite of what others were doing with gear change patterns at a given time. Not to mention that they started using 1st gear and running out the gear changes longer only after the engine downsizing happened.

Not to mention that they were getting better fuel mileage than everyone in the R8 days with the shorter gear changes. I think it has to do with traction control and using that to run taller gears since they started using 1st since 2011.