Re: 2.5 to a 5.7 mercruiser swap 16ft open bow
I Took a 4.3 Auto angine and modified it. The bolt pattern are already in the block to use the marine Engine mount. Coupler fits and so does the Bellhousing. So yes you can modify it. You might need to build new fittings for the enginemounts in the boat.
Just remember that auto motor drive accessories don't have the required spark arrest features for use in an enclosed space (I/O doghouse) that can have fuel fumes present (the blower does not count as safe & reliable substitute for a marinized auto engine). In particular, auto alternators, auto distributors & auto starters are NOT a good choices.
All of that ^^ info can be found in a search for automotive motor swap....
Spend some time & look around the engine forums & you'll find that there is a lot of info in here. See what other's have tried w/ various levels of success & failure. That way you can make a more informed decision about how you'd like to proceed.
I do agree w/ jimmbo, but would ask what's the weight difference between your straight 4cyl & the proposed 5.7 V8? I'd be willing to bet that beast will cause you to squat low at the stern, and that there would need to be some significant changes to the structure of the hull, engine mounts, transom, and transom connection to the hull bottom, sides & cap to support that V8. All of that will also add weight to the stern area. If you make that large of a jump in hp, torque & speed, the rest of the hull & all the stuff connected to it (seats, seat boxes, consoles & windshield, will need some attention to make sure they are great shape as well.
But that's all just IMHO, and as Bond-o said, yeah it's possible. Just make sure your gas credit card is in good standing, it'll guzzle gas compared to your current motor.
