Re: Supercharger and 4.3 EFI
As I mentioned above, I've looked into the issue of trying to get a significant gain in performance and as a "newcomer" to i/o boats got told a number of times to go with bigger engine / more cubes.
I picked up a 350 ca. 1989 vintage from what I can tell, original 260-270 horse, roller cam block (with hydrolic flat tappet cam in it), and decent old style 1.94 / 1.50 heads, mercruiser engine with everything for $500 last weekend. If you look and are patient you might run across something similar or boat that has one in it and an owner that just wants it out of the yeard (or who's wife or x wants it out of the yard...). The one I dragged home needs a water pump, turns over by hand or with the starter and shows even compression on the cylindars. I'm going to build to either 383 with cleaned up / marinized late model vortec heads or fresh "stock" bottom end and new aftermarket heads, either set-up gets new cam, blueprinted, balanced, etc...
Point is that using a cheap used small block engine set-up and readily available off the shelf parts, I wind up with a total upgrade investment of max $2,500, will probably gain gobs of torque and 100 to 150 horse if I'm relatively conservative in the engine build. That's with a very mild small block that should be very reliable is easy to tune, easy to work on and has a new and very solid for the amount of power bottom end. Note that going with aluminum exhaust manifolds on the 350, I make up all of the weight difference between the v6 and this engine. Oh, and don't forget that I get to offset the upgrade cost by seling the v6 package... it onlyu has about 40 hours on it, and has vortec heads, roller cam, edelbrock intake and carb, new manifolds and risers, etc... Since the 350 came with everything including bell housing, y pipe, alternator, intake and carb (4 barrel q-jet), starter, etc... I can sell the 4.3 as a complete replacement or upgrade engine that runs great has been carefully tuned and is just broken in.
The minimum cost for the 4.3 blower set-up without touching the bottom end would probably be in the $4k or higher (maybe a lot higher when said and done), and MIGHT be a major tuning headache... then once you get it right, if you're pushing the same kind of power you can get out of an inexpensive smallblock set-up say 350 horse, who knows how long until it comes unglued... The really tough thing is that there is very little available for the 4.3 once you get out of the realm of the typical stuff so after market parts are hard to find and expensive. and then finally, the weight thing... have you looked to see how much weight you gain if you go with true marein blower set-up? it puts you pretty close to the small block with cast manifolds in mst cases i think...
Of course there would be something kind of cool to having a 4.3 set-up with the blower on it...
Note that in either case you have to add the expense of a gear change and reprop... I found a used upper gearcase complete that looks very clean inside and out for under $400.
Just food for thought - I'm no expert.... Sorry to ramble, I type way to fast for my own good sometimes... Cheers! Tim R
