Hey guys i'm looking to squeeze a little more power out of my 454 for next summer. Im looking to put together a reliable set up without breaking the bank.

I have a 24' Banana 454 TRS set up currently running 54mph gps in the chop. I'm spinning a 23p Mirage at 4500rpm.

My current motor is a 1991 454 4-bolt main truck motor out of a Winnebago. It is all stock, smog cam and everything except for a Marine DUI distributor, a couple carb spacers and a 850cfm marine double pumper. I'm also running a Stainless Marine exhaust. The long block is very similar to a Merc 330. It has penut port heads, cast crank, and i belive 7.8:1 compression.

First let me say that im thrilled that the boat even made it past 50mph with this motor! It has been super reliable for the past two seasons but i would like more for next season. I would be happy with a solid 60mph.

My plan is to re-ring, replace the bearings, swap to a double roller timing chain, and swap the cam and valve springs. Its a very low hour motor so im hoping to reuse the stock rotating assembly. I have an oval port Weiand Stealth intake that im considering port matching the heads to. What do you guys think about this practice? Im really shooting for maybe 400hp and do not intend on spinning it past 5000rpm. Also would anyone like to recomend a cam?

I'm really looking to just get some respectable, reliable speed for next season without killing my TRS. Im finishing up my degree and paying tuition in cash so my funding is a little tied up at the moment! Next year is a different story, this is a one season motor and after that its just a spare. So what do you guys think???

"330 on roids" comes to mind.

Damn that rv motor isn't doing to bad . If it was a non catalyst carb eng could be the exact same gen 5 mill with the non emissions cam that came in boats rated at 330 .if it was orig a tbi egr motor you have a ringer .
Take.some good cell phone vids of it doing its thing sell the heads for top peanut port dollar and go big

Its a Mark IV block. Had a Quadrajet on it stock. Deffinitely an odd motor for '91 being carbureted. It had some god awful twin smog pump emissions system on it.

Unless you do something to get the compression up, you aren't going to gain much. I would look into finding some closed chamber heads, gasket match, radius, and bowl blend.

I think and know, one season....ah one year even...goes by real quick.

The "RV" engine has an anemic camshaft. Its NOT the same cam that merc used in the 330 engine. The "RV" engine, had something like a 194/204 camshaft. That would be first on my list to go, along with the smog pump lol.

A set of the large oval mid-70's heads would probably help airflow and compression, especially if you open up the valve pockets and add the 2.19/1.88 valves. I believe the 820 casting GM head had something like a 114cc chamber, which might gain you a point or so of compression. You could also run a thinner head gasket - I think Cometic makes one that is .020 thick. Add a Performer RPM Air Gap intake and you are good to go! Also, there are a lot of take-out 454 / 502 mag roller cams laying around out there if you look for them. Of course, you would have to spend the money on a set of retro roller lifters and the correct pushrods.

I threw a 224/224 108LSA cam in one of those 7.8:1 truck engines, stuck it in a kid's 80's buick 2dr with 3:42 gears, 3000 TCI converter and the f*ker ran 12.8's. Headers of course. What a piece of crap that car was, and it was a stock Mustang with Flowmaster's killer. LOL.

right now that 850 killing you..way to big for that engine...a merc 502 HP500 only used a 800, you need more compression 9-1 or so some of the large port ovals would work well and a decent cam for sure...can get to 500hp without to much issue