Engine Rebuild Stroke or Stock

[shackmaninc]

Hello all, My dad and i are rebuilding the volvo penta 570a that came with our boat. We are trying to decide whether or not to stroke it or keep it stock. Would like to hear anything you guys have to offer whether it's been something you've heard or experienced. We are thinking we might need the extra torque and better gas mileage. The boat is a 1972 searay 4200 lbs 24' It came with a volvo penta 290DP-A duo-prop. We are mainly going to be using it for fishing and strolling. We are doing all work ourselves minus the machining. so that will save a bunch. Please any advice or knowledge you guys have is appreciated. Thanks

 

[gbeltran]

Re: Engine Rebuild Stroke or Stock

Extra torque and better gas mileage do not go in the same sentence. A bigger engine is going to use more gas, especially in a carbureted boat application. If it were me, I'd want the larger engine in that boat. The cost to build a 383 is almost the same as rebuilding the 350, as long as you weren't just thinking rings and bearings. Choose your parts wisely, don't go too high on the compression ratio, pick the right cam as the stocker you have now will be undercammed in a 383.

 

[shackmaninc]

Re: Engine Rebuild Stroke or Stock

Alright yeah, i was thinking to keep the compression around 9.2. also do you think running hypereutectic pistons would be fine? And how much Added HP should we expect to see?