ORIGINAL: brjensen71
I apolagize, I don't mean to lead anybody on.
For my own entertainment, I am trying to see if I can make a ST90 turn a APC10X10 prop 16,000. While it may not possible or practical, and I may spend three times as much as buying a Jett 90lx, its all in the fun of trying.
The piston modification were to the skirt to uncover the ports when the piston in at BDC. I'll try get pictures of what I have done posted
I jumped to conclusions too soon.
Maybe 16000 rpm is too low to deliver the 2.5 hp that the prop requires at those rpm. It can be done I think, but components should match the tune to a T.
The best is, when there is ample header length in relation to pipe cone length. A very short header with a long cone probably will not get you there.
Someone with boating experience using .90 engines may have good ideas about the pipe/header combo to use.