The LS engine may well respond differently in a boat than in a car but our 2002 Corvette (5.7 350 h.p.) has 114,000 miles, uses no oil between changes, still gets the same economy and has the same power as when it was first broken in. With cam, heads, and headers it is easy to get 425 h.p. The LS3 makes that h.p. in stock form. The LS7 in our Z06 is a brute! I could only imagine a 29-32' stepped Fountain with twin LS7s. 85-90+ m.p.h?

One of these days I'm going junk yard scrounging and snagging a LQ9 out of an Escalade and putting it in a single 22-23' Bravo Drive boat to see how it works.

I drive a 2005 Escalade ESV with the LQ9 Police Edition and it snatches that 3 ton beast around like a rag doll. In comparison I have had Suburbans with 454's in the past that wouldn't stay close to my Escalade.

I think the 5.3 and 6.0 LS motors are the sleepers of this era. My brother has a '94 Silvarado Step Side 1/2 ton with the fiberglass bed and rear fenders that is a serious candidate for a 6.0 LS....talk about your classic sleeper!!

I'm itching to put a pair in a boat.

the corvette used a different type of pcv system if I'm not mistaken it uses a port in the valley cover and not in the valve cover. the valve cover location sucked up tons of oil. thats why most people are running catch cans to reduce the amount of oil in the intake.

the lq9 has 10:1 compression ratio just watch that in the marine environmen. but yes they are stout engines with out a doubt. lol the 2005? i believe and up lq4 got the same internals as the lq9 with the exception of the piston, dished vs flat top. but the rods are the stronger ones used in the lq9.

I ran a lq3 extensively for GM in a super light 24 Cigarette Firefox with a Volvo drive. I like the engine. It
was a 72 MPH boat would have been faster with a single prop. (boat went 83MPH in f1 trim hp 500 carb)
Steve

just run the the stock rockers with the CC kits, adding the heavier roller rockers upsets the lightweight valve train according to the LS people...thats all we used in out 1000hp 6.0

But what all would it take to get one of the lq4's to make 500hp? I know you said 450 with just a cam swap, headers and tune.

I'm probably being conservative on my figures. 500 hp is easy with some head work. I just want to keep my torque curve in the lower rpm range so I'm not porting the heads. Yes porting can make big numbers but can kill low end power. A stroker kit in my build I'd be pushing mid to upper 500... but that much more grunt to the engine would destroy my alpha drive. So I'm keeping the stock cubic inch. They cranked out 1200 hp out of a 4.8 with a turbo kit. A guy with an s2000 with a bone stock 5.3 junk yard engine put a turbo on it and broke 9's in the 1/4.

So a cam swap and turbo are they way to go on these motors? I am the same way on i don't don't want to be turning 7000rpms.
Id like to be making good power and never go over 5500rpm. Plus im still up in the air about doing this swap into my velocity 280.

You can alway build a stroker ls. The bigger cubes will help shift the power band. Match that to a good custom cam and headers with the truck intake and power will be brutal under 5500. Like I said they are 300 lbs lighter than a bbc. Talk to bob madara about a good cam. Yes there are issues you need to address. But ill be covering most of them on my scarab build and on this link as well. You could alwaya strap a magnuson supercharger on these bad boys and really pick up some major grunt. They usually pick up well over 100hp at the wheels on a stock motor. Have a cam made for that in mind and a custom tune and that will make all the powe you could want.

After some reading and research, your right they did make big power with the 4.8 on a dyno. But if you read into things more and think about it, a dyno isn't putting anywhere near the load on a motor that car/truck will. plus if your putting it in a boat you can multiply a car/truck load by 10, So you would never get that same motor to last very long in a car/truck let alone a boat. I'm looking for a good 500-600hp and not wanting to kill and engine by twisting it to the moon and back so i'll prob do a cam swap and maybe a little turbo setup. that should be enough to get the boat back into the 85-90mph range and it still hold together.