Same track has different grip/physics when changing track number?

While doing some experiments I came across this issue:

For the 2006 CSM mod, Melbourne is the 3rd track instead of 1st one, as it was in reality. For experimental reasons, I was using the 2001 track instead (by changing the 2006 track profile with TSM so it uses the 2001 one) with 2006 Melbourne performance file.

After doing some hotlaps, I changed the track order with TSM, moving the Melbourne 2001 track to the first slot of the profile. I also made sure to load the same performance file in GPxPatch as well. The difference is staggering! The same car has better grip, acceleration, and top speed. The lap time was cut down by a whole 2 seconds, from 1'29s to 1'27s (which was also the target time I was aiming for).

Needless to say I'm quite baffled by this. As I mentioned, I picked the same track, same car & driver, same performance file, the only difference was the track being moved from 3rd to 1st in the profile. Is there any place I should check for the cause of this? Answers are much appreciated.

Interesting thing. I think without CSM it would be the same. Unfortunately I'm not an expert in CSM because I never use it.

It happens when the track does not have magic data attached to it. Then the game will default to using magic data from the original 2001 tracks, which is hidden in the GP4.exe.

In your specific example, by using the track on slot 3 it takes its parameters from Interlagos (track 3 in the 2001 season), which has lower engine power as it's around 900 meters above sea level (in non-turbo engines, power is dependent on air density). So when you switch the track back to slot 1, which is originally sea-level Melbourne, you get a visible boost in engine power.

Edit: aerodynamic grip is also dependent on air density, that's why it's also lower for original slot 3.


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Edited 1 time(s). Last edit at 09/20/2023 03:35PM by Prblanco.

Thanks for your reply, Prblanco. However, the Melbourne 2001 track that I linked to in the track profile has a .tmd file in its folder, which I'm pretty sure is the magic data that TSM uses? When I checked the track in TSM it also had all the parameters in the magic data tab.

Edit: I should also clarify that I was using "Load only current track" in CSM options, so shouldn't whichever track I choose always be in slot 1 in the game?



Edited 2 time(s). Last edit at 09/20/2023 05:59PM by candle1252.