difference between a 2500 and caddy 6.0

[wolf396]

Just out of curiosity, does anybody know exactly what the differences were between the ls1 6.0 put in a 2500/3500 and the one in an escalade/denali/1500ss?

[carson84]

i'm not sure but probably the difference is in the cam. the 2500 is more for low end torque and the caddy is more overall performance

[2500ak]

Higher compression vs. lower compression. The LQ9 needs to have higher octane gas because of that. Also the Lq4 is cammed for torque, the Lq9 is cammed for higher horsepower. The higher compression comes from flat top pistons vs. dished pistons in the LQ4

[N0DIH]

According to my LS1/LS6 book.

From 01-up
Same cam PN 12561721 196/207 @ 0.050" 0.467/0.479 on 116
Same heads, PN 12562317, 210cc/75cc, 71.06 cc chamber volume (note boys and girls, 5.3L heads are excellent place to get heads that have smaller chamber, but some port work is needed to bump up flow as the 5.3L have smaller ports and only 200cc/70cc volume in the ports, but 61.15cc chambers...
Same block, 99-01 12551364 (LQ4/LQ9), 02-04 12551364, 12573581 and 12577184 (LQ4/LQ9). Service part replacement PN 12551366 (LQ4/LQ9)
Same pistons, PN 12575663 but up to 2002 LQ9's got moly coating on skirts and heat rejection coating on tops to stop cold start noise. All 03-up have same side coating on the pistons, these are erutectic cast aluminum with no valve reliefs
Same 80mm throttle body
Same MAF
Same Intake
Same Crankshaft, PN 12559768
Same Rods, PN 12568734 (shared with all 5.3L V8's)
Same Valvesprings PN 12553696

LQ9's have a Premium fuel program, LQ4's don't.

Now the 99-00 LQ4's do have different cam and heads (iron heads on some). If you need details there, let me know.

LQ9's had coated piston skirts, later LQ4's got them too.

The early LS6 cam would be a sweet one in the LQ4/LQ9, and the late one a bit better yet. But you will be losing some bottom end, but get some killer top end....

Now to make matters worse (this book has its share of minor errors). It lists:
LQ4.....364 CID.....6.0L.....9.4:1......12575147 and 12575148
LQ9.....377 CID.....6.0L.....10.08:1...12499467

Now, note the CID. It is incorrect. The latter part, 12499467 shows up at as the LQ9. So that is correct, but the specs on the compression, I highly suspect pistons ARE different contrary to the book's PN. Watch this post for more details....

[ATMINF]

I have also heard that the LQ9 had better rods(early on), but not sure that later years of the LQ4 and LQ9 had the same. Also the heads were different (even the aluminum ones) in the early years, but about midway thru the heads were the same on both motors.

[mabutler]

Higher compression vs. lower compression. The LQ9 needs to have higher octane gas because of that. Also the Lq4 is cammed for torque, the Lq9 is cammed for higher horsepower. The higher compression comes from flat top pistons vs. dished pistons in the LQ4

[Stratosman]

Higher compression vs. lower compression. The LQ9 needs to have higher octane gas because of that. Also the Lq4 is cammed for torque, the Lq9 is cammed for higher horsepower. The higher compression comes from flat top pistons vs. dished pistons in the LQ4

Well put-exactly. LQ4 is made to work, not fly around town all day, though a goot tune will almost get you the LQ9 horsepower anyway.

[N0DIH]

Pretty much 02-up, 100% identical
99-00, LQ4 only
01, both, but VERY minor diffs, nothing to snivel about. Except what I suspect, pistons...

What it comes down to, 01-up they both make the same hp, same reliability, same everything assuming the same tune and fuel.

Same rods, all trucks, 5.3L & 6.0L, only the LR4 4.8L had different ones.

I have also heard that the LQ9 had better rods(early on), but not sure that later years of the LQ4 and LQ9 had the same. Also the heads were different (even the aluminum ones) in the early years, but about midway thru the head were the same on both motors.

My book is sorta confusing on the LQ4-LQ9. It shows same PN's on heads, same pistons, but yet confirms a few places that there is a compression difference. It talks about not supercharging a LQ9 due to compression, and ok on LQ4. Same with dropping on LS6 heads on a LQ4 and LS6 intake/cam will make same power as LS2. But on LQ9 the compression would be too high. Go figure. So if you ask me, the pistons MUST be different, the PN's there MUST be wrong in the book.

Anyone got a LQ4 and LQ9 that can find the head part numbers? Anyone got any LQ4 and LQ9 VIN's and I will call up GM and dig around at a dealer?

Allthough it is a good book, it is chock full of errors, like the book was rushed into production and didn't get a real good lookover to check for data errors.

[N0DIH]

See my updates to the post on 14FEB08 @ 08:54pm my time....

Watch it for updates.

[Stratosman]

Pretty much 02-up, 100% identical
99-00, LQ4 only
01, both, but VERY minor diffs, nothing to snivel about. Except what I suspect, pistons...

What it comes down to, 01-up they both make the same hp, same reliability, same everything assuming the same tune and fuel.

Same rods, all trucks, 5.3L & 6.0L, only the LR4 4.8L had different ones.

Then why does Chevy list the 2003 for example at 300HP in the Silverado HD and 340 HP in the Escalade?

[N0DIH]

Like I pointed out the book is somewhat error prone, so take it for what it is worth. I would put it at 98% accurate....

I do suspect pistons are the ONLY mechanical difference. So the slight bit of compression bump up and 91 octane PCM tune will account for it.

Still same cam, heads, rods, MAF, etc. So if you want near LQ9 performance, get a high octane tune, or simply just toss in a LQ9 PCM tune OEM. More or less the same.

Then why does Chevy list the 2003 for example at 300HP in the Silverado HD and 340 HP in the Escalade?

If Ed Wright can get 31 hp more out of a L29 454 on 87 octane, it would be easy for GM to do the same with half point more compression and a 91 octane tune.

Run a LQ9 on 87 octane and I would bet the power would drop into the 330 range.

[ATMINF]

I remember a post in (I think) SilveradoSS.com that talked about this and I recall that there was a difference in the rods. The LQ9 rods were a little bit more beefy. I remember pics the guy had posted between the two motors(I don't know if that was for earlier motors or the entire line). I think the poster had said it suprised him, because he thought the only big difference was the pistons. Hell I say that the motors are so darn close, that a good tune makes the LQ4 close to the LQ9 power anyway.

[N0DIH]

If we get a VIN from a LQ4 truck and LQ9 truck, the local GM dealer can give us the rod P/N's.... Last 8 digits of VIN is all we need. And what year so we compare year to year...

[wolf396]

so its safe to say at least more compression and a different program... makes sense. lots of interesting stuff here, guys.