ORIGINAL: hooty301
What would give more power to a engine like my 61, a nonmuffled tuned pipe like the one made by Macs or a Performance Speicalty Ultra Thrust muffler?
The nonmuffled tuned pipe may give you a little more power by letting you tune your engine to a particular prop but the UT and Jett tuned mufflers work well. Where would you mount a long tuned pipe on a boat with the engine in the rear?
High rpm racing engines turn small diameter props and work well on very clean air frames. They do not work well on not clean airframes because of drag. Boats have a lot of drag and that is why they are so much slower the aircraft. Therefore I suspect a high rpm racing engine will not work as well as a high torque engine. Until you reach the theoretical speed of the prop you should go for more thrust (large diameter props). A 12" prop at 12,000 rpm has more thrust then an 8.8 prop at 22,000 rpm. One of your post testing different props indicates more thrust may be needed for more speed. Just my thoughts and they could be wrong.
