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Originally Posted by dereknkathy
(Post 4580524)
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.
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There's a small block Whipple floating around on here for sale
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Originally Posted by Donzi Z22
(Post 4580528)
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 ?
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 |
Originally Posted by phragle
(Post 4580527)
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. |
Originally Posted by class6
(Post 4580531)
There's a small block Whipple floating around on here for sale
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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).
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