ORIGINAL: Elwyn
I ran an Enya 19 on an ARF Flite Streak and it was a very good match. I didn't use any gear and the weight was around 23 ounces. I used a 9-4 prop but can't remember what the RPM's were.
I have a worn, low compression 25fp on my arf streak and it is too much, I needle it rich to keep it from running away. At the end of the flight it goes lean for a few laps and tries to corkscrew me into the ground

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I think a .19 or .20 would be the perfect engine for this plane.