Can prop limit rpms?

[Eddie Ray]

Can the wrong prop drastically lower rpm? Aq125a 270od only reaching 3000rpms. Can the prop cause the low rpm? The max should be about 5000rpm. Out of the water she goes easily to 5000 ,under load in the water. She won't get over 3000,even with plenty of throttle travel left.
Thanks
Eddie

 

[scooper77515]

Re: Can prop limit rpms?

Higher pitch props can pull off your upper RPM limits.

For example, mine is supposed to redline at 4400-4600 rpms. With a 23 p prop, it stops at 43 mph at 4200 rpms. With at 21 p prop, I get 49 mph at 4800 rpms.

Higher pitched prop eats at the holeshot, as well.

 

[45Auto]

Re: Can prop limit rpms?

Doesn't matter what it will do out of the water with no load on it. Pull off half the plug wires and it'll still reach 5000 RPM under no load.

Prop pitch will affect most engines at about 200 RPM per inch of pitch.

Most likely the prop isn't your problem, you would have to be in the neighborhood of 10" off in the pitch for what you're seeing.

Has it ever run correctly previously with the prop that's on it now? When's the last time it had a complete tune-up and compression check?

 

[scooper77515]

Re: Can prop limit rpms?

i agree, it shouldn't pull off 2k of rpms.