ORIGINAL: Paternguy
Thats correct, I was shocked too, I checked it several times. Maybe I just got a good one. LOL
I was OK with the weaker performance, after all it was a cheap engine.I was getting 13,500 on a 12x8 before i put the pipe on it. This engine (at least the one I have) was definitely made for a pipe, it has really come alive.
Thanks for the followup. Good deal.... you indeed have an exceptional engine. Hang on to that puppy.
Both the ST91 and OS91 are little more thank over-grown .61 engines - they really perform well on the same conventional "60" size props. From what Ive seen, too many guys over-prop these. Sometimes with disapointing results. Although the best I was able to get from the ST91 was about 13K on a 12x8, with the jett muffler. The OS 91 runs about the same, both prefered the 12x8. The H-650 deep-baffle setup appares to provide a great deal more boost. I may have to play with it again.