So whats the secret behind this motor? Buddy of mine has it in his 2005 GMC 2500hd with a standard transmission, (nv4500 i believe) and this fawking thing runs amazing. I mean i've never see a 3/4 ton, ext cab short bed truck run this good. Now granite he has a hypertech programmer on it, intake, and exhaust, but no motor work done what so ever. Beat an civic si the other night, beat an s-2000 the other night. Beat a few blown out cummins diesels, Powerstrokes, even duramax's. I just dont get it. He's raced the same truck only an automatic and its not even fair. GM definitely did something good when they designed this motor. Anyone know any secrets on it? Only thing I can think of is how the exhaust is. Now i'm not sure if its stock or what, but from the manifolds back, its two seperate pipes, with one cat in each, then they go into a 2-1 magnaflow muffler. Is this dual exhaust set up factory? He didn't do the exhaust, he bought it with it already on, but common, factory duals? pretty sweet if true and would surely help out alot.

Secret is in part cylinder heads .

LS-series motors work very, very good... I have the same engine in my '04 Silverado SS and it moves...

Works in the WTF-J! I added the GMPP "Hot Cam" and it rocks.

Whats funny is the 6.0L LQ4 (2500HD) is a pretty mild Gen III vs the LQ9('04 Silverado SS ) . It has low compression vs some of the others. Reason is its designed as a work truck and run on low octane gas and endure abuse.

The heads and high compression and PCM (for the higher compression) is what really makes those motors shine!

Now add a cam and they really start waking up!

Whats funny is the 6.0L LQ4 (2500HD) is a pretty mild Gen III vs the LQ9('04 Silverado SS ) . It has low compression vs some of the others. Reason is its designed as a work truck and run on low octane gas and endure abuse.

The heads and high compression and PCM (for the higher compression) is what really makes those motors shine!

Now add a cam and they really start waking up!


Yeah--it was almost too easy with a PCM4Less $170 PCM, a set of long tube headers, and a billet-servo shift kit for the 4l65...

anything small he could add to it to make it run that little bit better? He's thinking of a cam. Are you saying switch computers completely with one from an lq9?

my friend has on 06 2500 hd with the 6.0 and he also has an 08 2500hd with the 6.0, the 08 definately has more balls then the 06, its like a whole different monster. He said that the newer 6.0's have some changes on them and are a little different then like the 06 and older, anyone know anything about this? I know the 08 has a six speed tranny in it. I've driven the 08 and for a big work truck that thing hauls balls. Its a Z71 extended cab short bed. His dad owns alot of oil lease lands and he works for his dad and all of his trucks get the shit beat out of them. The 06 doesnt have a straight body panel on it and has been ran hard, but the motor is still strong though. Its the diffs and the transfer cases they have issues with...

my friend has on 06 2500 hd with the 6.0 and he also has an 08 2500hd with the 6.0, the 08 definately has more balls then the 06, its like a whole different monster. He said that the newer 6.0's have some changes on them and are a little different then like the 06 and older, anyone know anything about this? I know the 08 has a six speed tranny in it. I've driven the 08 and for a big work truck that thing hauls balls. Its a Z71 extended cab short bed. His dad owns alot of oil lease lands and he works for his dad and all of his trucks get the shit beat out of them. The 06 doesnt have a straight body panel on it and has been ran hard, but the motor is still strong though. Its the diffs and the transfer cases they have issues with...

The newer motors are actually 6.2L with broader availability of aluminum blocks. The LQ9's are great for NA operations and the LQ4's with their lower compression are preferred for boost.

I've driven the 08 and for a big work truck that thing hauls balls. Its a Z71 extended cab short bed. His dad owns alot of oil lease lands and he works for his dad and all of his trucks get the shit beat out of them. The 06 doesnt have a straight body panel on it and has been ran hard, but the motor is still strong though. Its the diffs and the transfer cases they have issues with...Its the LY6 in the new 07-up HD's has a iron block 6.2L with (VVT) Variable valve timing. They are basically the same motor as the L92 same heads and intake but iron block. A good tune and they will make 400hp+ easy! The six speed auto helps as well with the DEEP first gear.

anything small he could add to it to make it run that little bit better? He's thinking of a cam. Are you saying switch computers completely with one from an lq9?No No thats was a general statement on the PCM's of Gen III V8's ability to control the motors better for performance and saving the motors if they detonate.

He will love a cam 50+HP easy! Several companies make good all around truck cams. Short of new ported heads that's about it.

If he wants max power, tell him to get a dyno tune with a wide band o2 with a 93 octane tune.


The exhaust on the HD's is already pretty big stock! He might think about long tube headers though.

About that exhaust, does it come stock how i described? no y pipe? Looked stock, as I didnt see any clamps or anything out of the ordinary.

yes it comes stock that way (except for his aftermarket muffler). Two pipes w/cats going to single muffler, then single out to rear is stock.

The key to the Gen III motors is in the heads. Their design flows a crazy amount of air for their size. If he really wants to grab some extra power without changing the drivability much, tell him to get some ported heads and a new cam.

I'll be throwing a set of ported heads with an LS6 cam in this spring. Once we get it tuned in, it should make about another 70-80 hp without sacrificing fuel mileage