I put this question in the general discussion area, which was wrong! I just bought a 28 Profile Cat. Never owned a Cat before. It has a 500EFI, Extension box, with a 28 four blade. With 60 gallions of fuel. It runs 72 mph on gps at 4400rpms. Called Profile and they say I should be running 80 plus at 5300rpms but with no suggestions whats wrong. Anyone have an idea.

Wow, is that WOT ? I would start by checking the basics, is your throttle open fully at full throttle ( check with engine off ) Then do a leakdown test, if thats ok then start looking at the prop.

a buddy of mine had a 28 profile cat,he had a 600sc in it,32 pitch,don't know what rpm's he was running but he was getting 95 mph on gps all day long.i don't see why you shouldn't be in the mid 80's.ah maybe just something stupid.goodluck.

What about gear ratio in outdrive in combination with the prop? Is this dream-o-meter or GPS speed? The speed is about right for the prop and rpm.

The 28 is a big boat and the Hp is a little short on power. Seeing that you are down on revs, the speed sounds feasible. It sounds like the prop might be a touch too steep or you have a 1.36 drive, in which case it's way too steep. Hopefully that's the problem, because after that I'd start looking at the motor.

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