Keith

Could the EGR fittings in the truck, or any LSx manifold be used to make wet manifolds with?

That seems to be the major stumbling block when installing LSx's into boats, since the Indmar and PCM manifolds seem to be prohibitively expensive.

Shawn MacAnanny

iTrader: (12)

I was actually considering installing an LS1 into a boat and know nothing of boats. What are wet manifolds?

G-Body

iTrader: (4)

Normal marine exhaust manifolds are water jacketed to keep temps in the engine compartment lower, because theres a lot less airflow in a boat than a car.

G-Body

iTrader: (4)

Do you mean used by putting water in them?? If so than not really. You could put water into them so that they are water injected which will help cool them, kinda like running a set of water injected bassett headers. But true marine manifolds have a complete water jacket around them. I have heard of people wrapping automotive manifolds with copper tubing (the aussie aluminum jetboat guys do it a bunch because they frequently use oddball engines that are not normally marinized)

I just had a thought though. I know a lot of people use BBC headers and weld flanges on. If the port spacing is the same you could use BBC marine manifolds with a 1/4 or 1/2" aluminum plate adapter. I think I know where my set of BBC exhaust manifolds are and I have a set of LSx manifolds......I will have to grab a tape measure and measure it up. It might be monday before I get to it though, I have to work sat and sun this weekend

What are you doing for marine accys? The ignition system is sealed so that would be ok, but what about a marine starter? Will a SBC starter bolt on?

Your giving me bad ideas, I have a jetboat and it needs a motor And I have just about gathered up all the parts to bolt a SBC into it....but a LSx would be soooo much better.

Keith

The whole thing got going when I bought a 5.3L to stick into my 4.8L Silverado. I plan on making the 5.3 into a nice 9.5:1 5.7 for the truck. That leaves me with a well running 4.8 that I could stick into my 1974 Caravelle project boat. It currently has a ~250 hour 250" Chevy six. Being that the bellhousing pattern is the same, I think I could run it in there. Plus it would allow me to make the motor cover shorter, giving me another foot or so of interior room, which would help in this little 17' boat.

You are right that they would not be jacketed manifolds, but water injected like the headers you speak of. I think it might be enough to keep them cool for enclosed hatch running.

I think the bore spacing of the BBC headers is too big. The Bore spacing of a SBF could work though. I've heard of LSx fox body guys hacking a set of 351 headers and putting them on LSx flanges.

G-Body

iTrader: (4)

I know some people have used SBF headers, but I have also heard of using BBC headers. I know where my BBC exhaust manifolds are and on monday I have the day off so I will go measure them and see how close it is.

Another thought I had today was to build a set of water jacketed headers using stainless steel pipe and fittings like parish did for his nova. It would take a bit more time because you would have to build a header inside a header but it is another option.

G-Body

iTrader: (4)

I checked the measurements today and the BBC manifolds spacing does not line up. The LS series center ports are about a 1/4" closer together each (1/2 closer together total) And the outer exhaust ports are about a 1/2 inch closer to the center each (1 inch closer together total). Hopefully the ford manifolds are a better match.

LS1GMCTruck

iTrader: (2)

There are no shortcuts to marine exhaust. You must use water cooled/water jacketed exhaust manifolds. The reasons are numerous. Having a pair of one-off, water jacketed tubular headers made is cost prohibitive. Trust me on this. I have been installing/rigging performance engines in boats forever. You have to step up to the pump & buy the proper marine exhaust manifolds.

Keith

hmmm...

Adapted SBF manifolds might be the way to go then.

LS1GMCTruck:
Since I'm ignorant to the reasons other than heat, would you mind listing the reasons for the proper manifolds for myself and others?

G-Body

iTrader: (4)

Another problem with running non-marine manifolds is reversion. You don`t want any chance of getting water back in the motor or to hit the back of the exhaust valves. Marine manifolds will have risers to prevent water from flowing back up the exhaust on deceleration.

Also the cooling water is not mixed with the exhaust stream until after the riser. The only exception to that is water injected headers, but in that case there is very little water injected and the water flow is basically cut off at idle because there is not enough exhaust volume to be sure it is pushed out of the engine. With water injected headers you need to either run a gate valve and constantly adjust the water flow based on your throttle position or run an automatic control valve (banderlog valve)

GraphicNature

iTrader: (6)

i think some boats come with a 6.0 in them check with the your local sea ray dealer and check on that just some food for thought, i have a ls1 on a engine stand for a spare and i have been thinking about putting it in my sea ray with a torquer 2 cam and a carbed the ls1 will bolt right to my alpha out drive lol

garys 68

iTrader: (1)

Even water injected headers are not made for a closed engine compartment.
Try finding a marine exhaust that is close to the LS and make an adapter.
I saw boat with a blown Chrysler hemi that used an aluminum adapter so he could bolt up BBC headers.
There are a lot of different marine exhaust manifolds that have been made for V8s; BBC, SBC, big/small/FE block Ford, Lincoln, Chryslers, etc. I wouldn't doubt you could find one where an adapter would work.

Rodder

iTrader: (2)

The Mastercraft LY6 comes with a variant of the LQ9:

http://www.indmar.com/ProductLine/In....0L/index.html

LS1GMCTruck

iTrader: (2)

One good reason(of many), is that the United States Coast Guard says you must use marine exhaust, which local marine patrols honor as standards of safety, or you take the boat home, and/or get cited, or get the boat confiscated in some areas of the country. That one reason alone should be enough. Need any other reasons?

pist0lpete

iTrader: (3)

I know mercruiser should soon be coming out with a 6.2L LSX based boat engine however I am unsure exactly when it will start showing up in boats.

LS1GMCTruck

iTrader: (2)

Neal, with MerCruisers main engine distribution plant being right there in your home town, you'd think you would know EXACTLY when they ship out the 6.2's!!! LOL! I imagine Merc is a big employer around you there. By the way, real nice '67 Chevelle you got there...