I have a pair of 1993, 330 hp 454's in a 31' Profile. We are getting ready to install a set of headers, shorty drives, and am considering engine upgrades. I run a pair of bravo 1's.

What would you do to up grade these engines as cost effectively as possibe? I am thinking a 450 hp or so motor, and wondering about a rebuild with upgrades, or a pair of crate 502's.

Thoughts? Thanks.

Beware of upgrades on the 330. That has a cast crank and I broke mine in two. There is a forum open right now that talks about the 330HP 7.4L. You are on the right track with the exhaust. I replaced mine with the EMI's. If I had to do it all over again that would have been the first thing I would replace.

Skip the EMi's and get some tubular headers like Lightnings or CMi's I've run both and the tubulars are way better than the manifolds.....my .02 I have 330's making close to 500 hp no crank failures, with good assembly they will live at 5000 rpm no problem.

i recommend 502 marine crate engines over rebuilding 330 will end up with 450hp 560 tq I have 1 new one in stock will sell for 5300 plus shipping 410-956-5381

We can offer you many options for your project, give us a call.
Mike
Roccard Marine Engines
www.roccardmarineengines.com
[email protected]
570-956-2840

what hp can you reasonably expect to get from a 330hp stock motor with light headwork, aluminum intake, Holly carb, headers, maybe a roller cam, but leaving the bottom end of the motor alone. I am wanting to get about 450 hp per motor but keep them very much daily drivers.

Next questions is cost....

Thoughts?

A resonable number to expect for a well behaved 454 NA that is a low maintenance engine is about 1 HP/cu.in. Although you can keep you peanut port heads, rework them with bowl porting and larger valves, they will limit you horsepower above about 400. It will have good throttle response and low end torque with the peanuts. To get up in the 450 HP range you will need to go to better oval port heads. Many guys like the World Products for the money. I use a set of the old 049 BB heads. The cast iron crank should be ok, but be sure to change to better rod bolts, and check for main saddle alignment. The cast crank will work if the machine work and assembly are proper. Go to a dual plane aluminum manifold,(air gap), upgrade the push rods to 3/8" go to a roller rockers and by all means upgrade the exhaust. The q-jet can be made to work with some tweaking, although some guys go to a Holley. A roller cam for a Mark IV I'm not sure is cost effective. There are many good flat tappet grinds available for what you are trying to do. Check with RMBuilder on this website for valve train selection. Get the engine balanced and make sure your bottom end machine work is on the nuts.
Good Luck

I failed to mention, that a goal of 450 HP you are going to need to address compression. The cast iron pistons should be upgraded to forged. I did however get good service out of a set of quality hypernutetics but if you can spare the cost go to the forged. Make sure you check quench and run around a 9.0:1 CR.

Very good advice and important. Cam, heads, intake, exhaust, and compression all have to match. if you are determined to leave the bottom end alone you could get a set of edelbrock oval port aluminum heads which have a smaller combustion chamber and will up the compression some. Its risky to leave the cast pistons in but Ive seen a couple people do it and survive.