Chevy LS1 engine in the boat

[HorizonblueDK]

I have a 4.3 V6 in the Draco 1800 (18 feet). It runs fine, but I would still like to have a V8 :joyous:.

But I don't want to add a heavy lump in the back of the boat, so I'm thinking about what can be done. An SBC is a heavy piece of metal.

It seems like the all aluminium Chevy LS1 is the answer for me. As far as I have found out, it has the same bolt pattern as the SBC, so it can be bolted onto the bell housing I have today. I don't know if the crank has the same boltpattern as the "post 1986" SBC, but it's no problem for me to machine something, so the coupler can be bolted on.

In general it's not really a problem to fabricate special parts for converting an engine into marine use; exhaust manifolds, brackets etc.

I would probably replace the EFI intake manifold with at carb one and find an MSD controller for the coils.

It may sound like I have already taken the decision, I haven't and I would like to hear some opinions on converting an LS1 engine into marine use.

 

[Alwhite00]

Re: Chevy LS1 engine in the boat

You would need closed cooling with the aluminum i believe. also need a crank spacer to match up to the old bolt pattern, flywheel? mounts?

lots of $$$ in a 18' boat.

LK

 

[xjdriver]

Re: Chevy LS1 engine in the boat

Lol idk how "easy" it would be to fab watercooled manifolds for the ls1 unless they are already made. And i highly doubt your drive would handle it. The boat would be a rocket tho

 

[mr 88]

Re: Chevy LS1 engine in the boat

Sell your boat.Take the money you would of spent on the engine and all related parts including new outdrive / prop and buy your bigger turn key go fast boat. A lot less headache and everything fits and works from the get go.

 

[180shabah]

Re: Chevy LS1 engine in the boat

The V8 is only 100lbs heavier than the 4.3

Aluminum intake and exhaust manifolds would cure that, but you would need fresh water cooling (a full not half system)

 

[Scott Danforth]

Re: Chevy LS1 engine in the boat

since the LSX motors are being used, you san most likely find marinized parts. however as stated, it will be cheaper to buy a new boat.

If it was my boat I would do one of the two:
First option - build a stroked 4.3 with aluminum heads and a decent cam putting out about 260-275hp (all bolt-in plug-n-play)
second option - pull the 4.3, go with a 388 stroker using aluminum heads and you are now double the hp of the 4.3 for less weight (however about 3 times the cost)

 

[Scott Danforth]

Re: Chevy LS1 engine in the boat

update, the billet stroker cranks for the 4.3 have jumped in price in the last few years to the outrageous catagory.

 

[HT32BSX115]

Re: Chevy LS1 engine in the boat

I would probably replace the EFI intake manifold with at carb one and find an MSD controller for the coils.

It may sound like I have already taken the decision, I haven't and I would like to hear some opinions on converting an LS1 engine into marine use.

You could absolutely do it. But there's still the problem of the camshaft likely being all wrong (reversion with a "wet" exhaust) and switching to a carb with an EFI cam etc.

ALL wrong ignition. You'd still have to install a marine (SAE J1171) dist/electronic ignition.

Everything that makes the LS1 a REALLY cool engine: electronic spark control, knock sensing, EFI would have to come off (which would reduce performance)

I think GM DOES have a marine rated EFI and ignition for that engine but plan on serious bux!!!

The compression ratio might also be too high for a marine application too........ and of course, you'd need a closed cooling system as mentioned above.....

 

[xjdriver]

Re: Chevy LS1 engine in the boat

You could absolutely do it. But there's still the problem of the camshaft likely being all wrong (reversion with a "wet" exhaust) and switching to a carb with an EFI cam etc.

ALL wrong ignition. You'd still have to install a marine (SAE J1171) dist/electronic ignition.

Everything that makes the LS1 a REALLY cool engine: electronic spark control, knock sensing, EFI would have to come off (which would reduce performance)

I think GM DOES have a marine rated EFI and ignition for that engine but plan on serious bux!!!

The compression ratio might also be too high for a marine application too........ and of course, you'd need a closed cooling system as mentioned above.....

Well not necessarily true..... LS1 5.7 Holley HP Computer and Harness 24x Manual Throttle - Turn Key Engine Supply

 

[thumpar]

Re: Chevy LS1 engine in the boat

Well not necessarily true..... LS1 5.7 Holley HP Computer and Harness 24x Manual Throttle - Turn Key Engine Supply

It doesn't say anything about J1171 or marine compliant. Unless you like blowing up boats you need to stick with j1171 parts. The LS1 is probably going to have the wrong torque curve also. It is made for a car not a boat that runs the RPMs we run.

I am not familiar with Volvo drives but would think your ratio would be way off and need something stronger.

 

[xjdriver]

Re: Chevy LS1 engine in the boat

Marine/shmerine, i love blowing up boats.its efi how is an "automotive" as you guys like to say efi system going to blow up a boat? Now i could understand a carb bieng dangerous. In the end it comes down to you, run the blower make sure you have no fuel leaks. I know im gona cetch flak for this

 

[thumpar]

Re: Chevy LS1 engine in the boat

Marine/shmerine, i love blowing up boats.its efi how is an "automotive" as you guys like to say efi system going to blow up a boat? Now i could understand a carb bieng dangerous. In the end it comes down to you, run the blower make sure you have no fuel leaks. I know im gona cetch flak for this

Well stay away from my lake please.

 

[xjdriver]

Re: Chevy LS1 engine in the boat

Well stay away from my lake please.

Dont worry a have an outboard, lol

 

[HT32BSX115]

Re: Chevy LS1 engine in the boat

Marine/shmerine, i love blowing up boats.

Yeah, The "Slip & Fall" Lawyers would REALLY LOVE YOU!!

 

[HorizonblueDK]

Re: Chevy LS1 engine in the boat

Thanks for the inputs.

I'm not gonna trade the boat for one that already has a V8. I've had it since 1996 and it means a lot to me. But I'm not willing to spend a fortune on an LS1 swap.

I was thinking about finding an engine from a low mileage Camaro, stripping it from all unnecessary stuff, including EFI and then start building.

The manifolds are the biggest issue. There seems to be a limited production of these, Indmar produces them, but I haven't found them sold as separate parts.

A company in AUS makes them, but I don't think they could fit a sterndrive boat.

Chev Gen III LS1 Manifolds Cassell Marine

One possibility could be to fabricate an adaptor that could be bolted onto the LS1 heads and onto these, Ford 351 manifolds. There are a few 351 manifolds to choose from, also stainless steel.

Last option is to weld them myself. I'm a professional welder, but I know it's not done on a Tuesday evening.

I'm not that worried about the camshaft, I mean, any LSX engine would perform better than the 175 hp 4.3 I have in the boat now, right?

If I was going to replace an old 454 in a 27 feet boat, then I would probably be in trouble.

Water reversion; well if the engine is running right, and the risers are a good distance above the water and there are flappers in the exhaust (I have that in my custom made system for V6) is it that big a deal then?

 

[thumpar]

Re: Chevy LS1 engine in the boat

If you are going to start with a vehicle motor use a truck motor. The cam in a truck motor is very close to a boat spec cam. Reversion is not the only issue with using a car cam. You will not have the right torque curve.

 

[HorizonblueDK]

Re: Chevy LS1 engine in the boat

If you are going to start with a vehicle motor use a truck motor. The cam in a truck motor is very close to a boat spec cam. Reversion is not the only issue with using a car cam. You will not have the right torque curve.

Yeah, but as far as I know, the truck LS1 engines have a cast iron block, and I would like to have the all aluminium engine.

Cam swap........

Regarding the question about the outdrive, will it hold the power from an LS1 engine?

It will, I have no doubt. Volvo drives are strong and I'm not punishing my boat.

 

[Alwhite00]

Re: Chevy LS1 engine in the boat

An alpha drive is good for 300 hp,

LK

 

[Scott Danforth]

Re: Chevy LS1 engine in the boat

LSX marine parts are available. There is an LS3 variant, and an LSA variant. However it would be expensive compared to dropping in an SBC with alumum heads.

As far as cams go, automotive cams have too much overlap, and that is where reversion comes into play

 

[xjdriver]

Re: Chevy LS1 engine in the boat

Hmm think i got the answer for the reversion and exhaust manifold issue- these babies,