KNOT-RIGHT

23' Wellcraft Nova XL
4700lbs
Alpha one drive
5.7 Vortec
600 CFM Holley
4 inch Magnum exhaust
with manifolds exiting through prop.

mercury Thunderbolt 15 1/4 x 19 prop
turns 4500 rpm at 48 MPH

WOT should be 5000 rpms.
How can we get this rpm and increase speed????
With minimal Expence???

Please Respond!!!

TomZ

iTrader: (2)

Try dropping the pitch to a 17 maybe?

Need more information about your combo. Considering that it's a stock engine and all (since you didn't say), I would guess it's probably pretty close.

I had a 355 Vortec engine turing about 4800 RPM with a 17P Mirage on a 23' 4 Winns cuddy (pretty much the same as yours). Both boats are quite hefty... that was the best configuration that I could come up with. I ended up building a 383 Vortec instead. Now I'm breaking drives.

Basically, without a big power increase your gains aren't going to be great. Try out some props and maybe work on the timing (there's usually a little bit of power hidden in there).

Again, we need more info.

jhnrckr

You can put a bigger cam, better flowing heads and a 750 carb on it but you are going to be hard pressed to get a hull that big over 55MPH.

baja2700

I ran the numbers and with your current setup you should run 48.57mph. If you went down to a 17 pitch and gained 200 rpm you would run 45.39mph at 10% slip. The alpha drive is fragile compared to the bravo and will not take too much more power. Your best bet is to have your prop labbed by Houston Propeller our any qualified shop, you will probably pick up 1-2mph. To run 55mph with a 19p prop you have to turn 5100 rpms.This is figuring that you have a 1.5 gear ratio. Thats alot of rpms without thru hull exhaust, roller rockers, cam, valve spring, carb reworked. Once your building that extra power you have figure out how to hold that Alpha drive together or step up to a bravo 1 and that gets real expensive.