Engine RPMs

  • Thread starter Keith Fullenwider
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Keith Fullenwider

I changed the prop on my Cat 38 and I think the RPMs are too low when motoring. The prop that was on the boat when I bought is was a Martec 2-blade folding. I contacted Catalina about a fixed three blade...they said put on a 15X13. I did so but the max RPMs I get out of the engine is about 2200. The engine will rev to 2800 without a load. At 2200 RPM the boat will do about 6.75,. I don't get any smoke, but the engine temp will go up to about 180 or so. The prop works great, smooth, good control in reverse, etc. I am about to change out the exhaust system, because I suspect backpressure in the system. Would this affect the RPMs?? The engine is a Universal 3-cylinder, 24 hp. Thanks for any input. KF2
 
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Gordon Torresen

Engine RPM

Exhaust back pressure will definately affect engine performance Measuring it is difficult and your proposal to rework the exhaust to find out is probably the same. It is a little curious as to why you are not blowing black smoke when turning 2200 with the "hammer down". The big thing is satisfaction with the performance. With all the good things you said, I'll not muddy the waters.
 
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