I have a new saito 91 4 stroke that i was going to put into a venture 60 that im building, but the heli bug built and im considering getting away from planes...

Im taking it the motors are entirely different right, and that there would be no application for my motor in the heli world?

4 strokes in heli's are few and far between.

The main difference in the 2 stroke motors between heli and airplane is the heli engines have larger cooling fins to cope with being fan and shroud cooled instead of hanging out in the wind and the carbs are designed with mid range performance in mind vice airplane engines that are designed to run flat out and most guys could throttle with a toggle switch (fly and land)

I know, the 4 strokes are rare, but i seen one...and i gotta say, the same reason i went 4 stroke in planes, i want to do it in helis...the sound.....and the power...and the sound....

Remember heli engines produce their power at a lot higher RPM than airplane engines run props. My os 50s turn 17000 rpm.

I suppose its possible and would require gearing changes etc but the only 4 stroke heli I ever saw couldn't get out of its own way.

I agree if had the appropriate power to weight ratio it would be cool though.

You can put a four stroke in a kyosho nexus right??

They made a kit called the Legatto that ran on a 4 stroke but the engine mount and gearing were different. Thats the one I've seen in person and it can't get out of its own way unless you run it on 30 percent nitro and lean it to the point of nearly burning up then its mediocre.

I love 4 strokes in planes, but in helis I am sticking with 2 strokes. If you could keep it cool I actually think a 4 stroke would be better in helis since they make more torque, but helis can be enough trouble without trying to make something work that no one seems to have been able to for many years now.

Definately opening up a whole can of worms with a stroker, Cooling and gearing is one thing also weight and size is another. I would stick to 2 stroke for heli's.
If you want scale sound for a relatively low price look at putting an MA ION in a scale fuse. The electric whine and gear noise sound like a turbine in some ways. Or a Gasser to a lesser extent?