when above 2.5k revs and lift off i get a graunchy whine from the engine/gearbox, any ideas what this could be?

 

I take it nobody knows then?

 

one of the bearings perhaps.. although may not necessarily be gearbox.. could be spigot (centre of flywheel) or rear prop support bearing.. would need someone to listen to it to know for sure.

other possibility is a diff.. difficult to know more from text etc..

Simon

 

what can i do to uprate the gearbox so it can take more power/torque and abuse?