I don't know if 7800rpm is safe or not, seeing how I only have one K24engine set redline to 6800 that way I know it won't blow up. I want a million mile engine. The funny thing do you really ever know if its safely turned what happens if a fly gets in and lick's the ECU that might throw it off then bomb K24or it goes lean that's very bad for a alu block. You can get away with a bit of lean on a 63 mitsu engine even though that can blow too. A k24 engine is very expensive like $3700 I see.You never use a power sander on your headlights too much friction. Its only plastic. I guess you found out the hard way. Oh well back to drawing board. I do a thought experiment -Einstein.