I assume the rules require a containment for moving parts similar to drag car rules. I blew up a clutch pressure plate on a drag strip when I was quite young. Fortunately I had a scatter shield around the flywheel/clutch. I had the stock cast iron flywheel housing that broke but a steel 180 degree housing saved my legs. I doubt I would have had the shield if NHRA rules did not require it. I was not afraid of nothing back then, only thought of ways to go faster. I had thrown the lining off several clutch discs but had never had the pressure plate to grenade itself.