ORIGINAL: MrGreenSpeed
If You use a mac header and a tuned pipe on lets say an OS 91VR DF engine with a mac 15cc pipe and the header cut to the max RPMs for an 10x9 or 9X9 or 9x10 APC prop
If I saw you running those props on that engine, I'd first try to talk you out of it, and if not I'd be seeking cover[:-] But i think your just using this statement for example.
ORIGINAL: MrGreenSpeed
You'll turn 20,000 + rpms in the air, however there is no midrange throttle response.
You run the engine at idle or (on the pipe) 3/4 to full throttle only.
Of all the DF engines I've come across, these engines, OS 46VXDF or the 91VRDF rev up like a an Indy car, scary fast and transition quite well. Better than any sport engine on pipe I've seen. OS did an amazing job on the carbs. Due to the port timing, these engines do want to idle faster and consume vast amounts of fuel quickly. Ya cant have it all, there's no fee lunch.