Budget 454 Build
 

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

That truck LE8 smog engine, in stock form circa 1985, used a 800CFM quadrajet if memory serves me right.

Rated at 230HP at 3600RPM. 385ft lbs at 1600RPM. Dead at about 3800RPM cam.

The "marine" version of that engine, simply got a larger camshaft, no real changes to the long block.. The cam, Which was simply the old GM LS5 camshaft. Used in the 350HP 396ci, and the LS5 454 engines from thlate 60's early 70's. 214/218* with .461/.480 lift, 115lsa. That cam is about dead at 4800RPM.

Like I said, that stock RV cam would need to be the first thing to go in the trash.

Be very careful, especially if it's not a completely stock rotating assembly. The cheap rebuilds people use for trucks /rvs use hypereutectic pistons instead of the cast used in Mark IV Mercs and Chebbies. They will not take much punishment like a cast piston, and not at all like a forged piston.

My boat had one of these rebuilt truck blocks in it. Guess what happened one day? Boom. A little extra heat on a cylinder and it went.

Also, if you do re-use the hypereutectic pistons, make sure your ring gaps are on the high side. If the ring ends even lightly touch each other, those pistons are gone.

the hypereutectic piston is stronger than a cast piston,but not as strong as a forged.

True.

However with the high ring placement on the Hypercracking pistons, I believe this makes them more suspeptible (sp?) than the cast in mild builds.

Susceptible* don't make me hijack an informative thread because of your spelling disasters! Get your priorities straight!
1, spelling
2 hear say
3 theory read on the internet
4 factual real life experience.

All mostly true !

LOL.

that short block runs good leave it together. once you push pistons out of a bore you can't justify reinstalling dished pistons. mebbe replace the bearings without removing crank. scare up a set of alum heads with 113 cc chambers and you will be in high 8's CR.

vortec heads. l29 engine. 100cc chambers large oval ports with ski jump in the intakes. cheap easy to find in boneyard. a little port work and they do 440 or so hp. 500 ft/lbs torque.

I may have what you need. 1991 454 mag parts that will all be coming off. Heads, pistons, rods, Crane 242 cam and lifters. I also have a

Wieand Stealth intake manifold. /then you may still be able to use your carb.

This is a very common question that people ask all the time. There is tons of valuable and great info on this site regarding this very question. I went through this about 4-5 years back with a bone stock merc 454/330hp. If you click on my name a drop down will appear letting you been my previous post. If you go back to near my first post and scroll through the titles you start seeing post about getting more power from a stock 454. I asked a lot of questions, got a lot of good info and posted updates on all the upgrades I did. When it was done I had changed the heads to large oval ports with closed chambers and stainless steel valves, a crane hyd flat tapped cam, roller rockers, I ditched the circulating pump for a cross over, installed comp cams pushrods, a Edelbrock performer rpm intake (not the air gap), a marine holley 750 double pumper, a K&N flame arrestor, stainless marine exhaust, a Cloyes true roller timing chain, Msd marine distributor, marine ignition box, marine rev control box and Taylor plug wires.I found parts on eBay, OSO, etc.... Most of these parts you can find used at 1/3-1/2 the cost of new. I got lucky on several parts like the carb (it was almost brand new), the msd box & rev limited were new (I found them on eBay new for $180.00). The roller rockers, pushrods, exhaust and distributor were used also and picked up at decent prices. Msd will also completely rebuild your distributor (with new cap, rotor, pick up, etc.... For around $140.00 (I had mine done 2 winners ago... it came back looking brand new!). I also picked up a set of Teague Marine valve covers on eBay for a great price. You just need to shop and look as often as you can because the great and good deals are jumped on quick! If you need any help feel free to message me your number. I'd be more than happy to point you in the right direction or answer any questions you might have. I run a blown 516cu bbc now with a M3 Procharger that pushes around 850hp. I've just keep building and changing things! Lol But for the most part, I've done very close to what you were asking about in your post. Good luck! Mark