super tigre engines during the 80s had low silicon pistons that grew like crazy...and got worse often after a few tanks through them, when the x40 pylon engine came out they were destroying rods left and right.the answer was new pistons, which were fitted by prather and shadel etc then ran very well. Os still produces true abc engines in their premium car engine lines.. the OS heli engines are ringed today and are operated at 16-20k rpm and live very well as ringed engines.