LQ4
2001-2004 GM P/N: 12561721
Cam is the same as Camaro, Corvette LS1 and LQ9 Cam
So I did a lot of research on the internet to try and find the stock specs, but found that there was some differing information out there on the specs and then they were always incomplete information to be able to fully define the cam profile. I ended up fully degreeing the stock cam in the 2004 LQ4 I got for my conversion, out of a 2004 GMC XL 2500. This engine is going in my 1991 V3500 Crew Cab. I used this information to compare a bunch of cam profiles that were available in the aftermarket to help me decide if I wanted to do a cam swap or not. For analysis I use Pro Racing Sim's DynoSim5.
For my purposes I wanted to have a lot of torque down low and as much or better than the 1991 TBI454 that came stock in my truck. Horsepower wasn't as big of a concern as this is a big truck that is lifted and running on 35" diameter tires, but I wanted to have more than the stock 454, which wasn't hard considering the stock 454 only made about 230 HP at 3,600 RPM!
In the end I was surprised at how well the stock LQ4 cam did compared to several "torque" cams available in the aftermarket. My choice was to stick with the stock LQ4 cam and just put headers on it and give it a good performance tune!
When I get time, I will post my graphs and numbers for the different cam profiles. BTW...my stock LQ4 analysis on DynoSim5 was pretty dang close to the numbers published by GM.
Specs: GM P/N: 12561721
(for reference: This engine had 96k miles on the odometer when pulled and I measured off of the side of the lifter body, not on the plunger to avoid any variability in the lifter plunger)
Adv. Duration follows the SAE J604 §6.1 specification of 0.006" Valve Lift for Hydraulic Lifters (0.004" Lobe Lift for 1.7 Rockers)
0.050" Duration is Lobe Lift
Advertised Duration: 281 Intake / 287 Exhaust
0.050" Duration: 196 Intake / 207 Exhaust
Valve Lift w/1.7 Rockers: 0.467" Intake / 0.479" Exhaust
Lobe Lift: 0.275" Intake / 0.282" Exhaust
Timing Events:
0.004" Lobe Lift (AKA: Advertised or Seat-to-Seat)
IVO 12° BTDC
IVC 89° ABDC
EVO 72° BBDC
EVC 35° ATDC
0.050" Lobe Lift
IVO 18° ATDC
IVC 35° ABDC
EVO 40° BBDC
EVC 13° BTDC
Lifter Ramp Rate = 2.17
My setup. Ignore the clutter in the background; I have things scattered everywhere at the moment!
DynoSim5 results for the stock 2004 6.0 LQ4. This is like stock configuration: stock manifolds with CATS and mufflers and with 14.0:1 fuel ratio. This gets the numbers pretty close. Stock ratings from GM are: 325 HP @ 5,200 RPM / 365 lb-ft @ 4,000 RPM
1
