RE: Engine modifications
There are a few other guys (not me...not yet anyway ) that could give you some exact numbers...maybe they will chime in here before too much longer?
From what I have read, I have gathered that the racing boat and racing aircraft engines have fairly similar timing numbers?
I would think that r.p.m. is r.p.m. no matter what type of prop (air or water ) the engine is spinning, it's mainly the shape of the torque curve and where the peak(s) occur?