the need for speed

[lavey in red]

What and how much will it take to achieve 60-65/mph from my boat. (1996 Lavey XTski w/marine power 330/hp and dominator pump "all stock") Looking into 450/hp motor
(454 or 502?) and pump work. How much rpm's can my pump handle and still work as family ski horse. Any leads would be helpfull.

[calboater]

you didn't say what speed you are currently achieving, or what rpm. Do you have a set back jet and/or a diverter?

[lavey in red]

Sorry. I also forgot to list it as a 21/ft
hull. I currently get about 54/mph at 4,300/rpm's out of the motor. That is fully trimmed with a place diverter. The pump is the set back type with the clean out on the outside of the boat.

[spectras only]

Hi Lavey, you might have a "AA" impeller in your jet,hence the low RPM despite being a big block.If you after top speed instead of good cruise speed you go to the "A"impeller.Chevy's like to rev higher than Fords so don't be shy to increase your RPM with a smaller impeller.Your engine may not being up to top tune if you have an "A" impeller right now and only turning 4300.A well tuned 350 smallblock could do that.Also make sure you have at least a 750cfm carb.A lot of people put 600's on their BB engines because Holley had graphs to tell, thats all it needs!On the contrary boats have an uphill battle until they are on plane and at 3/4 throttle.A 450 HP engine would help tremendously compare to your basic 330 HP low compression engine.

[ULTRA28]

The first thing you need to do is find out why you are only getting 4300 rpm. The 1996 Marine power 454s rated at 340 hp is good for 4600 rpm with the stock quadrajet carb with standard exhuast and standard cast iron intake manifold. Your pump probably has a stock "A" or maybe a "AA" cut impellar, either way you should be getting 4600 rpm. The 21 lavey is a little heavier than most 21s out there, but if you are currently getting 54 mph its doing pretty good. Most 21s will only get about 55 to 57 at 4600 rpm provided there isn't any hook in the bottom. From what I can tell you need about 5000 rpm with about 450hp to get 60 to 65mph. There isn't much you can do with the stock 454s to get to that. Do you have a diverter? Do you want to modify your pump and motor to get to 60-65 without spending too much?