Should not be lifting and coming down on the motor at the end of the track. This could have been part of the reason the crank broke.
Just clutch it and put it in nuetral.
I agree. Looking at the video on the blog, the torsional load on the crank when lifting off at high rpm while still in gear is enormous. You shouldn't use engine braking to slow the car at all. The crank, rods, pistons and flywheel are at full rpm and then suddenly being asked to slow down in an instant. Feather the throttle, clutch in, into neutral and coast to a halt. Sorry about the damage, though. That hurts!