This is Concerning my 28 scarab excel with single 454(330)/bravo1
I was having serious performance loss with my boat.
Did a compression test, all cylinders are low, i actually have one at 0psi, my highest was 128 and all the rest between 90 and 30...
Somehow the boat was still getting me around.

The engine has already seen a rebuild and still has cast components.(from previous owners)
Is this engine even worth putting money into? if it was a 454mag i would simply rebuild it but its not.
I was leaning toward buying a 502 and rebuilding it and adding some sort of tbi ( sniper efi) or doing an LS engine and rebuilding to 4-500hp.
The bbc is more expensive as an engine but i dont need to buy new manifolds and wat ever else is needed for conversion.
The LS is attractive because i can get it with wiring and ecm in runing condition for 1000cad.
I want to get the most out of my next engine as my drive can safely handle.

Im in Canada and have winter to fix this up, let me know your toughs on this.

i dont ,,dont think an LS could or would use same exhaust set up as 454?????
not sure ,,i dont know anything about ls motors,,,only BBC
i see there is a lsx454,, for 12,000 bucks...
so i can get an ls motor running for 1000 bucks??? sounds like deal ,,but will exhaust fit???
good luck.
fyi,,,i spent close to 20k,,upgrading my 510s to 547,,but everything was upgraded..

Taken the engine you have to your machinist of choice and have him install a kit to stroke it to 496cui. It's that simple. Find the proper marine cam to go with it. Have the heads brought back to spec or buy a good set of aluminum heads from FloTek for about the same monies. Also a good aluminum intake.
Personally I'd go the aluminum head route as you get superior flow capability which is easy HP. I'd also upgrade to a roller cam profile. Once again a little more cost for a serious boost in torque.

LS will be very expensive with the peripherals. It will be $10G CDN. with bolt on stuff if you go with headers, plus build the LS.

What is your budget ???

Thanks all for your input, keep it coming
The LS does have a different exhaust, and buying those marine ls manifold is just the beginning of all the LS specific stuff to adapt. The cheaper initial engine cost will probably be quickly balanced back by all the conversion parts to fit it in. It seems to be less common then i expected.

I will be looking into this, is going for a forged crank critical for a 500 hp goal application or way overkill? cast crank rotating assembly's are everywhere from 1500 to 2500.
No idea if my block is 2 or 4 bolt main

Thats wat im afraid of, initial cost is attractive, but the whole conversion cost gets you back pretty fast.

I don't have a budget, wat ever gets me close to 500 hp and dunking the boat in the lake by Mai 2022.

Going to a forged crank now will be exponentially cheaper than finding out a cast one isnt up to the task....Aluminum heads will let you squeak by with aq little more compression too.

Also given some parts are currently hard to get, You probably should figure out what your going to do and start it sooner than later.

Check out this budget 496 build.
567hp at 5,700. More than 550 ft# of torque from 3,000 to 5,300.
Uses a cast Eagle stroker kit, Iron Summit/Dart heads, hydraulic flat tappet cam, rpm airgap intake and a swap meet Holley 4150.
For a boat, the cam should be on a 114 Lobe Sep instead of the 108 in the article.
The Howards 129261-14
Might be a better marine choice for you, has a 114 lobe separation, less intake duration, and gentler ramps..

Thru Merc BBC exhaust manifolds and thru hull exhausts, this build will yield over 500hp at 5,200rpm.

The Eagle cast kit as listed in the article is fine for the power levels and sub 5,500 rpm range you are looking at.

If you plan to run WOT at 5200 rpm for ten minutes solid with no breaks, then you are better served with a 4 bolt main block. Your block may or may not have 4 bolt mains.

One thing to remember us that the Eagle cast cranks are cast steel. Unlike the factory cast iron. Cast steel is much stronger. Plus the factory rods in the 330hp 454 have 3/8 rod bolts compared to the 7/16 in everything aftermarket. Once again much stronger. So the Eagle cast kit will more than handle the power your looking for. A factory block can easily be converted to 4 bolt mains. Though I really don't think you'd need to unless you might want to make more power down the road.

And... This is what it looks like if you take the cast crank gamble and the house wins... (how much more is a forged crank?)