Jet boat low top end speed

[Rob holland]

Hello, I recently purchased a 20.5 elite carrerra jet boat and I have a question. It has a 454ci engine and it should go upwards of 70mph but I can only get it up to 45mph. It does not have any debris inside and the engine runs strong and seems to be working as it should. Is this an issue with the jet drive or the impeller? Or what?

 

[adrianp89]

I don't anything about these boats. If your RPMs are strong and where they should be then probably impeller.

 

[Murf'n'surf]

Some things to discuss are elevation, impeller pitch, impeller condition, impeller housing clearance. You may have an impeller pitched for hole shot and not top end. Do you know what the factory pitch was?

I assume you are getting your speed off of a gps and not the dream-o-meter on the dash? With a speed loss of 30mph, you are likely looking at an impeller/housing issue.

 

[Cobra Jet Steering LLC]

Always check on the fuel if it is stale it will do that