hi guys, i was kickin around the idea of doing the top end on the 454 twins in my 1985 42ft. wellcraft Excalibur. It has TRS drives, edelbrock 750 carbs, k&n air cleaners, but other than that bone stock 400 hp 454's . the boat is heavy and runs 55 with a good tailwind. i was planning on shaving the heads a little, some new hi flo valves, clean up the ports, portmatch, edelbrock cam, (non roller), timing chain, the usual stuff. but i was wondering if (hypothetically) if the horses were upped to 550 max;( i realize more is required to attain 550hp) how much top end would i pick up. obviously i don't tow skiers, i don't care about holeshot much, i just would like to be in the low sixties. i was also thinking about new manifolds but am not sure how much horses stock manifolds are good for; should i change them and what kind of after market manifold is good without spending more than $2500 on both of them.( low budget hp) from what i read, lab finishing the props is a good idea too. any thoughts or suggustions? i don't know what shape the ports are of the valve sizes offhand as they are still on the boat. i also have a 1976 24 foot donzi with new crate engine and bravo drive for $14k if anyone is interested.

A few years ago I did the 370 horse engines in a 42 Eagle with Gil exhaust, generator, and a/c. Heavy boat but very nice to ride in, especially in rough water. That boat ran 52 gps at 5200 rpms, and cruised at 42-43 at 4000 rpms. I'd guess 60 would be about all you'd want to hope for with reliable 454's (read turn-key, pump-gas motors without blowers). You've got good motors to start with though. Get the compression up to about 9.5, have JimV at Valako Race Heads trick up the heads (everyone will probably tell you to go to Darts or Merlins but I like the Chevy heads), call Ultradyne Cams for a camshaft recommendation, and get a good shop to machine the block/crank/rods, and get some GOOD exhaust. You might be able to buy a faster boat but I don't think you could find a better rough-water boat than the Eagle. Fred from this board is looking hard at one.

I know of a 42 that would run in the low 60's with two 509's-they were good for about 550 hp. You may be hard pressed to get 550 out of 454's and still be reliable.

A built 454 with a good exhaust and roller cam will make 470hp. If you want more, you'd be looking at a blower. Either a 174 or a 250 (prefered) will get you to 550hp.