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502 w/ 25 pitch prop, What RPM?

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502 w/ 25 pitch prop, What RPM?

Old 03-30-2006, 07:56 AM
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Default 502 w/ 25 pitch prop, What RPM?

I bought a 1987 28' Saber a couple months ago and I was able to run it for the first time this past Sunday. I dont know anything about what was done to the motor accept it was recently gone through by More Power in Grand Rapids, MI. They replaced the rings and a piston, put in new bearings and polished the crank and cam. It has IMCO manifolds and a hi-rise Dart intake with a 950hp double pump Holly carb. I do not know the HP rating for the engine.

It has a 25 pitch 3 blade mirage prop on it and when running wide open I was running around 4700-4800 rpm and on;y getting 57 - 58 mph depending how the drive was trimmed.
Is this prop a little too much for the engine. It seems like I should be in the 5100 - 5300 rpm range. I dont know a whole hell of a lot about props and what would be the best match for what I have.

Am I where I should be or should I go with a different prop, and if so what one? Any info would be appreciated.
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Old 03-30-2006, 08:17 AM
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Default Re: 502 w/ 25 pitch prop, What RPM?

Did you do a leak down test on the motor? It sounds like you should be getting more from that set-up than you are.

The way that it is running now i would say that yes, you are over-propped. If there is no rev limiter to check I would think you want to be at 5100rpms.

There is alot of guessing here...you best bet would be to get the motor on a dyno and see what kind and where it makes its HP.
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Old 03-30-2006, 08:28 AM
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Default Re: 502 w/ 25 pitch prop, What RPM?

Try a 23 four blade.
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Old 03-30-2006, 08:37 AM
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Default Re: 502 w/ 25 pitch prop, What RPM?

A buddy of mine has a 4 blade 22 pitch that I can try out and see what it does, I also have a 23 ptch 3 blade mirage off my 454 330hp motor that I could try also.
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Old 03-30-2006, 08:44 AM
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Default Re: 502 w/ 25 pitch prop, What RPM?

is it a 1.50:1 or 1.36:1 drive?
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Old 03-30-2006, 08:54 AM
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Default Re: 502 w/ 25 pitch prop, What RPM?

Originally Posted by wieland77
A buddy of mine has a 4 blade 22 pitch that I can try out and see what it does, I also have a 23 ptch 3 blade mirage off my 454 330hp motor that I could try also.
The four blade 22 bravo-1 should be a good starting point with a 1.5-1 outdrive. I would have thought that your setup would easily turn a 24 b-1 4 blade.

I run a 28' with a 509, can turn the 24 pitch b-1 prop to 5800 rpm. Probably could turn a 26, but don't want to torque the outdrive too much.

Last edited by Wobble; 04-03-2006 at 10:29 AM.
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Old 03-30-2006, 09:10 AM
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Default Re: 502 w/ 25 pitch prop, What RPM?

My dive is a 1.5 gear
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