i have a 89 wellcraft nova xl 23 ft it now has a 350 mercruiser 260 hp does 40mph at 4600 rpm i can get a chevy 355 block but not sure on what to use to build and if i can use parts from my motor now would like to get the boat to do 60mph but anything over that would be awesome so i dont know how much hp i will need or exactly what to do i have been told to just buy another boat but its goin to be paid for and would rather customize it so any info would greatly be appreciated

if it were me i would find a BBC 365 mag or bigger,,you will be lucky to get that boat in the 60's,even if you had a 383 small block you would be lucky to see 50ish..

That's a sizeable boat for a SBC. Having said that the SMALLEST I would recommend is a 377-383 stroker. You could go bigger in a small block but that would entail aftermarket blocks and borderline astronomical prices. Certainly a fun experiment but not cheap.

As far as utilizing existing parts for a 383 stroker in the 350-420 hp range the only items you most likely would be able to utilize are the mounts, bell housing, distributor, perhaps valve covers, water pump, starter etc. All the other parts would need to be of the high performance variety to get near the 350-420 hp range. That might net you 55 mph. You would need a good stroker crank, fairly healthy cam, Vortec/Dart/RHS heads etc.

I would suggest you get the biggest N/A cubic inch motor you can afford assuming you have a Bravo drive. It won't be cheap, but will get you closer to the goals you wish to achieve. Even a very mild cam 500+ inch BBC would offer you more possibilities down the road.

I wish you the best of luck on your goals.

Easier and cheaper to buy a boat that will already run 60 !

it takes app 20 hp to gain 1 mph,that means to see 60 mph you need app 400 more hp,i think that would not be cost effective,that being said,i believe you either need to lower your goal of 60 mph,or put the money you would spend to achieve this goal into a more efficiant hull ,sorry,but it is what ie is!

Been there and done that. I had a 21 IMP (very close to nova hull) I build a 383 sbc with Performer RPM Heads, roller rockers, exhaust, big carb. All just to see 57 mph. I had fun doing it but was depressed with the outcome. I was young at didn't listen to anyone. Needless to say, I threw out about $2K all for 9 mph. Sounded bad azz though.