||01-14-2012 3:34 PM
^ This. There's no displacement to be had from boring. You're talking a few cubic inches. Even on a motor with a longer stroke you're not likely to get more than 10 cubes out of it. Blocks have been thin wall castings since the 60s for the big 3. .060 is about max, .080 is really pushijng it, and every block is different. In a marine application you want your cylinder walls thick and strong due to the loads as well as raw water cooling and corrosion from the coolant side.
Stroke is where you get displacement. Heads are what make the power. If you want more power look at heads first, unless you're bottom end is due for a rebuild. Upgrade the heads to aftermarket or do some port work on your iron. Get rid of the restrictive cast center risers and get some proper headers or at least higher flowing cast manifolds. On stock displacement this will make a big difference in power and should improve efficiency as well. I'm not a Chevy guy so I can't recommend what components you use in a SBC stroker. If it were a Ford I'd be able to tell you, but don't want to guide you wrong for a Chevy. If you're handly with mechanical work it would be a fun winter project, though I wouldn't pull apart a perfectly good engine to do it... I'd wait until it needed a rebuild unless it was really struggling.
Stroke, as we discuss it in your typical SBC/SBF or BBC/BBF doesn't mean much to RPM. The differences are that small. For higher RPM you need to be worried about using good rods and keeping rotating weight light (lighter pistons, good valvetrain, etc.). I shift the BBF in my truck at 6500 RPM, and I consider that a lower RPM build and cheap with stock rods. I've had people tell me everything from big blocks won't turn that kind of RPM at all, or it'll self destruct if you try. Some people just don't get it, typically Chevy guys which is likely because the BBC is such an inferior platform and is very limited in what you can do.
Whenever the BBC is my boat dies it'll be getting a 460 based stroker (545). With the 454 I'm turning 2300-2400 RPM at 21 MPH with 1320 lbs in a 23' boat with no struggle at all. Not much difference with or without the weight in how the engine pulls. With more weight I might have to drop some pitch and gain a few hundred RPM but I can't fathom seeing 4000+ RPM to do riding speed. It's just not necessary with a bigger engine. In a 545 package you can easily get 600 HP and 800+ ft/lbs and maintain a nice idle so it has good dock manners. Heck, is a 393 stroker (Ford 351w) you can push over 400 HP easily and not need to turn that RPM. I'd assume you should be able to get similar from a SBC as SBF and SFC are very similar. If you're turning 4000+ with a stock 350 you should be able to shave at least a 500 RPM, if not more, with a 383 stroker build with torque in mind (build it like a truck engine). Focus on your rotating assembly, valvetrain, and oiling system if you'll be turning sustained high RPM. Oiling can be a major issue in stock engines at sustained high RPM.