I used Scalextric Classic, I went up about 18"
Of course you went up about 8" along a 12' straight to a hairpin, then up the other 10" over about 13'. But you could go steeper. One note, if there was too much magnet that steep climb really heats up the motor.

Of course you went up about 8" along a 12' straight to a hairpin, then up the other 10" over about 13'. But you could go steeper. One note, if there was too much magnet that steep climb really heats up the motor.