ORIGINAL: Cambo
Another question on topic
Why can a 4-stroke engine turn a larger prop without rpm loss if they have less horsepower than an equivalent size 2-stroke?
Cameron,
With a reasonably sized prop, this simply isn't true.
If you take a .91 sport two-stroke engine and a .91 (non-supercharged) four-stroke engine and put a 14x6 APC on both, the two-stroke engine will have an advantage.
If you use a much larger prop that will load the two-stroke engine, to significantly below its peak torque RPM and the four-stroke will still be at, or above its own peak torque, the two-stroke engine could be scavenging so inefficiently that the four-stroke engine will make more torque and spin that big prop a bit faster.
I understand they have a better torque curve, but why?
It is all in the timing. If you port and time the two-stroke for low RPM, it will retain an advantage to low RPM...