PD's arbitrary 1 to 60 slider doesn't really help with working that out now does it. However, if they'd done it as a percentage slider, that would at least be useful in this regard.
If you still wanna work it out, it's just gonna be a case of trial & error.
It's a straight ratio.
1 hour racing real time with setting of 24 = 24 hours track time.
1/2 hour racing real time with a setting of 48 = 24 hours track time.
2 hours racing real time with a setting of 12 = 24 hours track time.
It's a straight ratio.
1 hour racing real time with setting of 24 = 24 hours track time.
1/2 hour racing real time with a setting of 48 = 24 hours track time.
2 hours racing real time with a setting of 12 = 24 hours track time.