01 28 velocity 502 mpi 57 mph on gps at 4500 rpm. 24 4 blade prop. Just bought boat.Whats wrong?

I t should be spinning a 24 inch prop about 500 RPM faster and you are down a good 10 mph on speed. Either not trimmed or down on power?

Tell us more, what brand prop, how many hours on engine, how was boated loaded, etc?

Is that at WOT? How many hours on the engine?

My 97 sonic 31SS with twin 502 MPI runs 5050rpm at 72.4mph on gps spinning Bravo 1 26 labbed 4 blades. you should be hitting you rev limiter with 24 blades dose your drive have 1.50 gears?

Confirm you drive ratio

That's a big single engine boat, I would try a 23 or beter idea, call BBLADES and see what they suggest for that boat.

A 28 velocity with a 502 spins a 26 inch hydromotive. He should be over 5000 rpm with a 24.

Check fuel pressure. Same problem with mine. Put new fuel pump. Now runs 5000 with 24 Bravo w/ 454 MPI

How much did the pump cost you?

The drive is a 1.50 the prop does not have a name on it.I checked fuel pressure it is 43 at idle Timing is set at 8 deg.I pulled the plugs ,cap and rotor they were horrible looks like they have never been changed even though dealer told me it had been tuned up.My fault for not checking at time of purhase.I changed fuel filter also.I am going to test in a couple hours and check fuel pressure at WOT.I am going to test with the current prop 24 4 blade.I am also going to take a 26 4 blade that I currently have and try that.I will update on results.