Generation IV Internal Engine - 09 LMG 5.3 Heads/Cam/Intake
03-13-2011, 09:33 PM
I am swapping a LMG I pulled from a wrecked tahoe with 900 miles on it. It's going into my 75 K5 Blazer with a 4L60e and NP241. Before I swap it, I'm willing to make any good "bang for the buck" modifications.
Is it worth going to LS6 Intake on this motor? What about the cam? I read on the forums that I basically have the LS6 heads. Is it worth changing to better cylinder head? If I can spend $1000 and get at least 75HP I will be happy to do so. What would you do, and how would you prioritize it?
03-13-2011, 11:06 PM
The ls6 intake is a good idea. The heads are actually not ls6. More of a ls2. Ls6 use hollow stem valves. And ls2 and trucks with 243/799 heads use conventional valves. Prolly make sense to go with a custom grind with the ls6 intake
03-13-2011, 11:09 PM
The 243 casting head is used with the hollow stem valves. For the ls6 designation. They are some of the best oe cathedral port head. So no need to upgrade really if u want to keep cost down. The ls2 also use the same casting along with other gm vehicles
03-14-2011, 08:58 PM
The LS6 intake isn't really worth the trouble most the truck guys stop swapping them years ago. Plus you have to mod the accesory drive. Plus the DBW TB will not swap over as its a 87mm unit and I am not sure there is a converter to run it, I know there is one for goin' early DBW to later one. Plus its an E85 motor so it has the larger injectors as well.
The new truck intakes Gen IV flow as well as the LS6. Theres data on the truck site somewhere.
The LMG is AFM (DOD) motor as well. I would ditch the Active Fuel Management too remove the lifters as well as the valley tray standard stuff etc etc...
I would have the heads ported and milled since you have to remove them anyway to remove the lifters. Then get a cam as well. Then port the TB and intake to 90mm. That should make some nice power.
IIR they were rated 315 or 320 HP stock
03-15-2011, 01:56 AM
k5's are beasts! haha
03-15-2011, 06:31 PM
ahh, how things can change overnight.
Last night I found a good deal at the local craigslist for a phab turbo kit for the LS1. I have been thinking about a turbo, but I didn't really want to do everything from scratch. I picked this kit up last night and I'll see how many modifications I have to make once I test fit the new motor this weekend. If I can make it work without too much cutting and welding, that may be an easy way to get to 400HP. Can't go much higher since I am on a stock 4L60E, but that should be just enough.
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