Re: Crazy idea? Maybe so... 383 Stroker?
I know several people in my area who run alpha's behind 400+ horsepower. I'll be one of them within another week or so (If I can ever get the time out of the office to finish all the details and swap engines out). There are others on here that do as well.
My understanding from doing my own homework before starting on my current project / toy is as follows... (Note that this is not from my personal experience but is based on the experience of others... I tend to find that "common wisdom" holds to a point, but when you dig into the details, there is typically a lot more lattitude for modifications then people think.)
The alpha drive is much more likely to hold up to more horsepower in a lighter boat. Mine's an 18', balsa-cored mod-v Checkmate with a pad, and will weigh a little over 2000 pounds fully loaded, gassed-up and running down the river with the new engine in it. On speed, I'm getting 55-60 now with a lightly modified 4.3 and am looking for mid 70's with the stroker set-up. Once you approach upper 70's blowout becomes an issue with the alpha drive (basically prop cavitates / loses hold due to low pressure zone created by the gearcase pushing through the water).
I'm installing a "mild" pro built 383 stroker... I started by buying a complete used 350 package and taking the block to an accomplished marine / race engine builder who happens to be local. At this point the original gm / mercruiser parts that are part of the new set up would fit in a shoe box... everything else is aftermarket / performance or in a couple cases new (ie. water pump).
The (marine) engine builder I used said the drive should hold up as long as I kept good lube in it, checked it often and didn't do too much of things like catching air jumping big wakes under heavy throttle...
bottom line is this, the more horsepower you push through any gearbox the sooner / more likely it is to come apart and the faster the contact surfaces are going to wear. Propper set-up, tolerances, lubrication and heat removal become more important...
I've got a spare drive in case I frag the first one and enjoy "playing" with this kind of thing or wouldn't be doing it.
The last point I'll make is that most of the stroker engines built for "mild" street rod applications have bottom ends in them that won't hold up near as long in a marine application as a stock engine. I was told that if I didn't go with a good forged crank, rods, etc... have it carefuly balanced, add a good oil cooler, run good synthetic oil after break in, etc... that the engine's lifetime would be limited if I ran it hard...
The other question you want to ask yourself is if your hull will be stable at higher speeds or if it will get scary, and whether or not you want to take the chance...
Is that what you're looking for?
Chances are that if you go with a good, stock configuration vortec era 350, add a good aluminum intake and carb, aluminum manifolds (weight loss where it counts!), it'll make a big difference already.
Do some searches on here and other places, there's some good information if you dig for it...
