99 Donzi Z22BR 383
 

Anyone know if the Z22BR hull will handle more speed,right now i'm at 54 mph indicated and 48 gps speed.
I have the 350 MPI Mag has 300hp with an alpha Gen 2 with about 100 since a jasper reman. What type of speed will
i see by adding a 383 475hp stroker and a Bravo 1 ?

Tell us how you plan to get 475hp out of a 383?

Going by what the machine shop says 450 to 475. So is it not likely ? Omaha, lots of kin there.
My family is from a small town called Plainview...

Well, it certainly can be done, but things like compression ratio, rpm, cam etc required to make that power in a 383 often are not compatible with day to day marine use.

You add 150 hp you will add about 10 to 12 mph.

How much HP to be used day to day with no issues ?

Trying to get something reliable and get mid sixes. Is there a rule of thumb for speed ?

Yes, the rule of thumb is throw lots and lots of $$$$ at it and it will go faster, maybe...

Rule of thumb is over 1.0 hp per cubic inch is expensive and unreliable. Put a 454 in it. Aluminum heads and it is essentially the same weight as the small block you took out. But you spend 3 to 5k and speedo will say 62 instead of 54. It is a paid for reliable nice setup.

I just googled the boat..it looks to be less than a 24 degree bottom? and it has a pad? and your seeing 48 mph gps with 300hp thru an alpha?

Before you start building anything, figure out whats wrong first. If its the bottom I saw in the google pik, with 300 hp you should be 10 mph faster.

The transom with the thru hull exhaust or the motor mount location will not work with a big block...So a 383 at 383 hp would work but I might see 10 mph ?

There's a small block Whipple floating around on here for sale

The motor mount
s will work, the holes for the thru hull exhaust will be different, But then again if you start building on the small block you will eventually need better exhaust with could possibly throw the current holes out the window too

It has a 22* hull and the pad is about 12" wide on the stepped portion of the back of the hull. about 5' long. Check for a hook in the hull ?

That could be the ticket...

475 hp with a 383 should be fairly easy with the right parts. I have a 355 built 20+ years ago that made 424 hp on the dyno with dyno headers (and it is EFI with all of the stock 1987 model 320 EFI hardware). With stock Mercruiser style manifolds and risers, my boat has run a best of 72 GPS with 2 people and light fuel. Mine is a 20 ft Checkmate with a very similar bottom to yours (V with a pad about the last 6 ft).