ORIGINAL: HaveBlue
ORIGINAL: DarZeelon
The K&B 7.5 can be easily converted to sub 22K use, by simply dropping the sleeve and raising the head accordingly, to decrease the exhaust timing to about 160-165º.
It will still respond well to a (longer) tuned exhaust. The mini-pipe in FBD's post will also be usable.
well that then defeats the purpose of getting this engine in the first place..
HaveBlue,
Unless you actually want to have this engine spinning at 22K RPM, or more, the standard timing of this engine is way more than what you want.
For 18-20K you want 160-165º and this engine has significantly more.
It is over-propped spinning 18K, probably to below its torque peak RPM.
This may lead to a lean-run, when this engine unloads significantly in high-speed flight.
Any engine propped below its torque peak will unload very significantly. If peak torque is achieved, or surpassed, as it unloads, it could reach ~23K RPM, which will require the high-speed mixture to be set
much richer than you normally would, with a normal high performance engine.