I've been lurking on this site for years trying to plan something for my Hummer.
My tired LQ4 of 189,000 miles has finally lost oil pressure. I'm sure after reading this site for so long that its the dreaded oil pick up tune o-ring but I have always wanted to add some more power so now's the time to do it. Its a leaky pig too and my driveway will thank me later.

I can get a brand new LQ9 450hp engine for about half price, GM#19370163. It comes with square port heads but I have a set or ready to go 243 heads that I intend on putting on it for now. That will allow me to use the existing intake system. These heads will bump the compression up to 10.9 to 11.0 to 1 so it will basically be an iron LS2 Z06 engine that should be easy to tune. . I know the cam is not perfect for a truck but it won't kill me either and I can use the stock converter with no issues.

My concern is will I have enough injector and throttle body for this set up? I have no delusions of it ever being fast and it lives in the sub 2000 rpm range but am I overlooking anything with the induction side? I think my best bet would be a set of marine 8.1 but looking for advice.


Thanks!

Tim

 

I looked up the part number and some of those are "listed" as cathedral port; most pics are square, so I will trust your judgement on that

If you're slapping heads, look for a short block, IMO. And if you're doing heads, no reason not to optimize the cam choice for your ride as well

You can do an LS2 TB for additional flow, and you will need more injector, without a doubt. Hows your trans?

 

Or you could fix your oil pump with a pickup tube o ring and then do heads and cam of your choice on the LQ4 in your truck. Way cheaper... and no at 189000 miles your 6 liter is not wore out by any stretch. Unless of course you ruined it by running it until it made noise or seized lol. Oil cooler lines account for about 90% of leaks on these trucks lol.

 

I got such a deal on the long block I couldn't pass it up but don't want to go thru the hassle of tbss and the return lines. I might add a blower down the road so this seems to be the easiest thing to do for now without committing to one path in the future
I agree on the cam and guess I might as well swap it now. The trans has been built with the thought of power adder down the line. My trans guy threw a bunch of Sonnex stuff in it and he says other than some huge nitrous launches it should hold all that I want to throw at it. I never forget its a 8000 lb truck. If it goes I'll upgrade to the 4l80E. He runs a 4l65e in his twin turbo Avalanche so I hope he knows what he's doing.

Thanks for the advice.

Tim

 

It would be much easier but then I will want to add power some how. The Lq4 runs strong, no knocks, no noise, not even a peep from teh valve train which makes me curious about what is failing. It needs to come out and get re-sealed anyway. These pigs are not easy to work on at all, despite how big they look. I omitted the oil lines a year or so ago tracking down other leaks. It will need a rear main seal again so I'm thinking there's a little play in the thrust bearing but that too is a guess.

The engine builder guy will take it on trade, so with GM warranty I'll be in the new engine for $2800. I don't think I can pass on that.

Tim

 

I don't how so many leak oil in random places lol. I abuse all of mine and they stay dry no matter the mileage lol. I would rather keep my known good running one than some rebuilder special that could easily be trash but whatever floats your boat!

 

I still think its a wise choice to optimize the cam while the engine is on the stand. Optimized for the weight, stall and head design. Better now than when its in the truck!

If Im not wrong, the LS2 TB is a bolt on for your current manifold; you may need an adapter harness tho

Overall its a good plan, follow thru with what you desire!

I dont think she weighs in 8k tho. My Tahoe with lots of H2 parts, DOM bumpers, extra tanks, solid links; blah blah blah is 5920 with a full tank. The Tahoe and H2 share a lot more than you might imagine. Your H2 is heavy no doubt, but I dont think 8k heavy. Maybe like 6200 heavy.

 

Its a brand new GM engine with GM warranty, no rebuid or reman. Gm #19370163

 

You could sell the rec port heads to upgrade that LS6 camshaft to a cam/spring/pushrod kit of your choice with money left for injectors and then some. The TBSS return is a simple bolt on with the Corvette tank fuel line that connects to the C5 filter. The 50 lb/hr gen4 flex fuel injectors are cheap and have good data for the tune. What's the word on getting that engine deal... I know you're not getting two grand for an old LQ4 trade in

 

Don't get the marine injectors. Buy what Red said.