by cynr100 » Thu Apr 04, 2013 8:27 am
Depends on the design application of the motor.
I had a 2m stiletto f/glass RC speed boat, originally it was equipped with a purpose built long stroke 23cc Zenoah w/cooled 2 stroke. I wrecked that during an "Oh my God" incident with a very large wave ( I was wave hopping 0.5 m waves at 50kph, got the bounce wrong) anyway I digress. The replacement was a short stroke Homelite 30cc 2 stroke, RC adapted for marine application and went like a pig, wrong motor for the wrong application, it would have been better on an air boat.
I have never liked HP ratings I prefer torque values that is where you get your real mojo.
Your 3.5cc may be rotating at 4x the speed of the 10cc to get the higher Hp rating but which one is going to turn the largest prop.
A 1m rotor is a fair size, I would opt for an engine that has a high torque rating (if you can get that info). You might also consider a diesel engine, known for there higher torque values compared to the same size 2 or 4 stroke petrol.
Not enough time in the day for all my crazy ideas, I'm not slow, I'm just pacing myself