I have a 25' 78 carrera ss with 454 merc trans and trs outdrive, im not to sure on whats inside, it has a torker 2 intake Holley dp (750/850) stainless log manifolds. I havnt checked but was told it has rect port heads (could very well be ovals) it has rod knock and needs a rebuild, i bought a reground stock crank. And am lookin at hyper pistons 30 over, but for $10 more i can get the same pistons for 4.250 crank with stock rods. Seems all things being equal (gotta hot tank, bore, balance both set ups) $300 more for a stroker is a no brainer. Im just wondering if there will be a down side to goin bigger? Im lookin for 9.5-1 comp power under 6000rpm id like to hit 500hp also could use a cam recommendation?

The crank is what creates the stroke and you already bought a stock one???? Are you going to buy a 4.25 crank????

Go with a better forged piston like some SRP's. Log manifolds are junk.

Making 500hp from a 461ci is not very hard with the right parts.

Pull your heads and see what you have for pistons, heads, and see what you have for bores.You might not need a rebore. And for all you know, you might have forged domed Pistons already. And you might have a forged steel crank already. It would probably take a little clearancing in the bottom of the block so that the connecting rods don't hit the block with the larger stroke crank.

Yes i would be buying the stroker crank if i decide to go with the stroker pistons, the 454 come out of a 76 monte Carlo in early 90s (according to p.o ) and since montes didnt come with 454s in 76 it really is a toss up. I suppose the smart thing to do, would be pull it apart figure out whats inside. I just figured on cast everything with original bores and 30 over being a safe bet of working out. You dont think speed pro hypers will hold up in a boat?

1) I've never heard anyone say "gosh this stroker motor is just too much power." Ever

2) Hyper pistons will work, but I'd recommend paying a little more for a forged unit.

I like were your going with that, ive read dozens of posts on this very question and it seems to be 1/3 sayin no brainer more cubes more power, 1/3 sayin stock stroke is more then enough to make so n so power, then the last 1/3 says everything being equal (comp, heads, intake ect) the stroker will make more torque but some how less hp unless u work the heads too

P.s im really tryin to get as much hp as can below 6000-5500rpm ive read lots on the trs out drive (basically bulletproof as long as u dont buzz it to death above 6000) the trs was actually main reason i bought the boat, it was between this and a 10yr newer boat that was same lenght and nicer but sbc (with rod knock) with alpha. It waa more of a cruiser then speed boat. But i didn't want to biuld a hot sbc then spit out alphas

At least pull the valve covers and see what heads are on it . If they are rect ports , then start pricing gen 4 rotating assy with dome's to match a 489 with 120cc chambers possibly a matching flywheel and balancer . Make sure whatever cam is in the motor now is not a street cam .