28 velosity 502 sick
 

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.

New max speed with a full tank of fuel and 2 people 62 mph at 4700 rpm with a bravo 1 26 4 blade.Is my problem in the prop? I would think it should be faster and turning more rpms.The boat has 76 hours on it.

Did you run it again with the 24? You should be a solid 65 in any water with the 26 spinning 4700-4900 depending on how you have it trimmed.

Yes it would only run 58 at 4700.

if i'm reading correct , your spinning 4700 with both 24 and 26 pitch bravo 1 4 blade props? , if less pitch didnt up your rpm's then you need to look at the engine , my first look would be at fuel pressure while running , fuel pressure at idle wont tell you if your fuel pump has the ability to move volume at pressure in the upper RPM's

what elevation are you running the boat at in comparison to the other's on this thread.

The 24 prop that came on the boat looks old.I do not know what brand it is.I checked the fuel pressure at wot it was around 43.I am boating in KY.

So what Prop do you all recommend?

I would call Brett at call BBLADES and see what they suggest for that boat. Test a couple different props, you only have to pay for shipping. He will get you dialed in.

Does the boat have mufflers or restrictive tips, inserts or anything like that?

I never thought about that. I will check but I do not think so.Thanks

How many tons of water are soaked into the hull? Probably zero but you never know.

I have never heard of that before.

Are Velocity still balsa wood core? If so, even if not, they can soak up water and get slow. Its unlikely for a newer boat tho.

boat should pull a 26 hydro with out a problem that is what came stock on it. mine had a 365hp mag in it stock and pulled a 24 hydro 5200 at 68 mph and that motor was tired