If the tech was mature enough I'd use a brushless motor. Internal combustion is silly. But until capacitors can match battery storage I'll wait.

For now I'll use what is on hand, an SBC. If I were to spend the money on a whole new engine it certainly wouldn't be an ancient big block, that's like going from FI to a carb. It will be LS based but not until the budget can cover a crate engine and mods.

I wouldn't say BBC's are ancient in comparison to an LS. The LS motor is still 80% SBC 1950's tech from a architectural standpoint. Yes it has a different main web setup, they changed the timing, some blocks were aluminum however millions of 4.8/5.3/6.0's were iron, moved the oil pump, better cylinder heads(any good marine BBC will have capable aluminum aftermarket heads) and other revisions, however it is and always will be a SBC... It's still an overhead valve motor and is fitted with some nice new tech and revisions, however it is not one bit revolutionary from a design aspect.

If I were in your shoes I would look nowhere but towards an LS motor. 6 liter preferably so you can run rectangle port heads which flow north of 300cfm out of the box.
You can get LY6 dropouts(rectangle port, iron block 6 liter with the good Gen IV rods) for under $2,000 around here. Closer to 1500 if you shop.
Put another $1,000 in cam/springs/pushrods and harness mods and you will have a 500+hp screamer that loves to turn RPM.
Sure, you can build a 500hp BBC cheaper but it's going to eat gas and have nowhere near the reliability of the Gen IV motor. There are guys making over 1000hp on stock bottom ends over on LS1tech.

There are no common parts between an old SBC(junk) and LS motors.

Edit - don't waste your $ on a crate engine. Go to the JY and get a complete takeout. If $ is an issue get an older LQ4 (pre-07, 05/06 would be best so you get Gen IV rods which are stronger than earlier), cathedral heads will also make great power, they actually outperform rectangles down low.
Return line, 255lph inline, C5 fuel pressure regulator is all you'll need for a fuel system. I've done a few LS swaps, they are VERY easy.

Please show me where I stated or claimed "common parts".... I stated design or general architecture and the LS has everything to do with a SBC. Id really love to see a 1,000hp stock bottom end LS live in a marine endurance application. Wouldn't never happen. There's a reason companies like ERL re engineer the factory blocks. I agree they are impressive stock, but not at 1,000hp.

I never said you said that they shared parts, easy killer.
I also never said they would live at 1k+ with stock internals in a marine environment.
That they will make that power is just a testament to how much more durable they are than the old SBC/BBC's which puked at 1/2 that power.
OP has a fairly light hull, an LS motor would handily push it around reliably(likely faster) and with much lower fuel consumption than an old carbed 454.

small boat or not, they all need a decent amount of torque and the only way you get that is cu inches. if you think a 600 hp sbc will be good on fuel, you are only kidding yourself lol. i'm not so sure a sbc is that much more durable either?? marine application is tough on any motor but when you don't have to wring out a motor to get hp from it (bbc) they will last much longer

+1 for me small block in a car rev it up have fun in a boat need the torque bigger is better work less to keep boat at speed but that being said i think small blocks have there place always wanted to see a 24 formula with twin hot ls's

An LS motor is NOT a slobbering old SBC.
There's another member with I believe a 24' skater or cigarette with 2 STOCK 5.3's that runs north of 100, he was shocked at the fuel consumption, to the point the gauges were questioned.
My old H/C GTO that made 550 would throw down mid 20's on the highway.
I have yet to read of someone putting one in something and being displeased with the performance.
FWIW, the L92 in our Denali has no problem propelling it to low 14's and it's stock other than a quicky home tune. The truck weighs almost 6000#.
Go look at some dyno #'s before you condemn them as having no torque like the old SBC's. Technology is here, time to embrace it.

Found the guy with the Skater:
http://www.offshoreonly.com/forums/s...-bravo-1s.html

5mpg @ 70 - terrible mileage.

Bor also has a 21'er with a built LS2.

I don't think anyone stated 1. A LS is exactly like a SBC(architecturally they are very very similar). I've gone over this in detail above already.. 2. Nobody said SBC's have no torque, BBC's just happen to have more for the most part, ie why they dominate this sport.

I've invested about 10k so far into my BBC and it's by no means some old turd running on antiquated 50's technology. I invested in Holley EFI for one. Trust me, I and many others here have the budget to buy a super duper LS, we don't because there is no benefit to doing so with the vast availability of a more powerful platform, the Big Block Chevrolet.

To the OP, sorry to de rail the shiz outta your build thread. Back to the original topic!

I'm not doubting that 500+" BBC will make more power/tq than an LS motor. It better. Nor that folks can afford to buy whatever they want.
OP was concerned with cost of building an LS motor when IMO and simple cammed LY6 will get him where he wants to be and will handily push the boat around.
I too apologize for derailing OP, just don't want you to make a choice based on bad info or facts.

not sure where the bad info is???? these are simply our opinions, just like yours, an opinion. nobody ever sad a sbc was a bad candidate just gave a few FACTS as to why he may want to stick with a bbc. don't compare a cats fuel millage with a v bottom, apples to oranges. btw, i've been down the sbc road with a pair of blown 355's. it was my decision to never run small blocks again because of reasons i have already stated. the op asked for advice and that is what he is getting, everyone has their opinion, he can take it or leave it. this shouldn't be a pissing match over sbc and bbc. we could start a whole new thread for that and i'm sure you would get lots of opinions, some good, bad and totally worthless

Up to 500hp I'd consider either. 600+ really leans in the BBC's favor especially if the boat get's a bunch of use.

Wow, its been a while since I've checked this.

If/when changing the engine platform from an SBC... I'm using an all aluminum LS engine, for weight, power and general maturity of the design. I understand there is no replacement for displacement. But a high hp motor can still generate adequate torque at the propeller with proper gearing. The concern of longevity for the engine is a little out of skew, Its a small boat, cranking WOT for long periods of time is exhausting for the driver as well. It only moves top speed maybe 10% of the time.

As for the progress, its pretty much at a stand still. Last time I was working on it, I was cutting out the rear bulk head and stringers. Got my finger with the grinder pretty good but its healed up now. Hoping to find time to get the stringers put in in the next couple weeks.

Looking forward to your updates on the hull/stringers.

Been busy remodeling our house and taking a late honeymoon to London, but coming back with all resources pointing to the boat.
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The Return
I made some final decisions on the direction of the build. It will be a fuel injected supercharged LS2, bravo one upper and either an SC or SportMaster shortened lower, the boat will have a 16" X-dimension and a -2 lower puts the prop shaft 4" below pad. So the blades should pierce the water and i hear a hydromotive P5 works well on these boats. Any higher on the x and the engine will be a balancing act i think.
Parts have started to arrive, I bought a new HP bravo transom assembly, Mayfair 2 ram full hydraulic steering kit and Lightning LS headers. Next on the list is a new B1 upper and engine. I haven't decided if I want a crate LS2, or rebuild a used one with beefier internals. If I can find a high mileage LS2 for $2k then it will be about even to buying a crate engine. In any case it'll take a while to buy everything to complete the boat. More coming soon while I begin replacing the stringers...

Click...
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Another Part
Still around, slowly buying more parts. Had a drive built for me. Bravo X upper and -2" shortened lower. Next on to gathering the engine parts and having a long block built. Once the engine is about done there will be more frequent updates.

Click...
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How did the project end up?