just out of curiosity

[bo brown]

18ft Hawaiian with a F428 Cob. jet. single 800 holley carburator @ 5300 rpm's. Can anyone predict what the speed would be. Someone told me they saw the boat run 90. I don't think so, 55 - 60, maybe?

[Cas]

somewhere between 60 and 75 maybe. There are a lot of factors to take into consideration as far as top speed goes. For example, the clearances in the pump, impeller size, boat bottom, weight of the boat and many more.
The HP of the engine and the rpms it turns the pump is only a portion of the equation.

[jetboatperformance]

somewhere between 60 and 75 maybe. There are a lot of factors to take into consideration as far as top speed goes. For example, the clearances in the pump, impeller size, boat bottom, weight of the boat and many more.
The HP of the engine and the rpms it turns the pump is only a portion of the equation.
Bo I'd have to agree with Cas , maybe 75 ,I have two lake boats running verifiable 80's , 90's a pretty tough nut to crack in a moderate hp v bottom jet , just being honest Bud ! Tom

[bo brown]

I just couldn't beleive that a 428 with nothing in motor would run over 90 mph. But I didn't know for sure. I've never seen the boat run. That's just what I was told. I'm gonna go find it to see how quick it is I reckon. I'll let you know when I find it. I know my boat on gps will run about 75. I had it at 70.1 with people in the boat and 2 tanks of gas.