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LS Engine Cam Test Comparison - Ultimate LS Cam Test

Hands On

By Richard Holdener, Photography by Richard Holdener

LS3 vs. LM7

Despite similar specs to the LS2 (increased intake lift), low-speed power production with the LS3 cam was down compared with the LS2. This was evident from the fact that the LM7 offered more torque up to 4,200 rpm. As expected, the LS3 offered plenty of power, producing 405 hp and 398 lb-ft of torque. This represented a peak gain of 91 hp over the LM7 at 6,500 rpm. We expected the additional lift offered by the LS3 grind to increase power over the LS2, but that was not the case on this application.

Engine Designation: LS3

Displacement 6.2L
Lift 0.551/0.525
Duration 204/211 degrees
LSA 117 degrees
Idle vacuum 21.3 in-Hg
Cranking Compression 175 psi
Peak HP 405 at 6,100 rpm
Peak Torque 398 at 4.900 rpm
Average HP 303
Average TQ 368
HP/TQ gains (over LM7 cam) at 2,500 -21 lb-ft
3,500 -6 lb-ft
4,500 +5 lb-ft
5,500 +47 lb-ft (49 hp)
6,500 +73 lb-ft (91 hp)


LS6 vs. LM7

The LS6 cam is a favorite among LS enthusiasts, but it seems from this testing that it falls short on the 5.3L compared with the LS2 and LS3 grinds. The LS6 offered a few more horsepower at the top of the rev range but was down compared with the LM7 up to 4,500 rpm. Compared with the LS2 and LS3 cams, the LS6 offered less power through most of the rev range, only equaling their outputs at the very top of the rpm band.

Engine Designation: LQ9 (Shared with Late LS1)

Displacement 6.0L
Lift 0.479/0.467
Duration 196/207 degrees
LSA 116 degrees
Idle vacuum 22.5 in-Hg
Cranking compression 185 psi
Peak power 376 at 5,900 rpm
Peak torque 389 at 4,500 rpm
Average HP 296
Average TQ 362
HP/TQ Gains (Over LM7 cam) at 2,500 -8 lb-ft
3,500 0
4,500 0
5,500 +23 lb-ft (24 hp)
6,500 +32 lb-ft (40 hp)


LQ9 vs. LM7

Though it did not offer the top-end charge of the LS2-LS6 grinds, the (late) LQ9 cam offered impressive power gains over the LM7 and would be a good upgrade for a 5.3L truck owner or someone looking to improve performance without sacrificing low-speed torque production. The slight loss of 8 lb-ft was more than offset by the 40 extra horsepower at the top. It's important to note that the power gains offered here would likely be magnified had we tested the cams on a larger 6.0L.

Engine Designation: LQ9 (Shared with Late LS1)

Displacement 6.0L
Lift 0.479/0.467
Duration 196/207 degrees
LSA 116 degrees
Idle vacuum 22.5 in-Hg
Cranking compression 185 psi
Peak power 376 at 5,900 rpm
Peak torque 389 at 4,500 rpm
Average HP 296
Average TQ 362
HP/TQ Gains (Over LM7 cam) at 2,500 -8 lb-ft
3,500 0
4,500 0
5,500 +23 lb-ft (24 hp)
6,500 +32 lb-ft (40 hp)

L33 vs. LM7

Contrary to popular belief, the L33 cam is not the same as the LQ9 grind. The L33 was essentially a high-lift version of the LM7 with a few extra degrees of duration. In terms of power, the L33 offered additional power over the LM7 cam but did not increase power as much as the LQ9. As expected, there was no change to idle vacuum, and cranking compression was within a few psi of the LM7. Though the L33 offered more power than the mild LM7, it's hardly worth the effort. Grab one of the hotter factory (or Crane) cams if you are going to upgrade.

Engine Designation: L33 (H.O. 5.3L)

Displacement 5.3L
Lift 0.479/0.479
Duration 193/193 degrees
LSA 116 degrees
Idle vacuum 22.4 in-Hg
Cranking compression 182 psi
Peak power 362 at 5,300 rpm
Peak torque 387 at 4,500 rpm
Average HP 290
Average TQ 357
HP/TQ gains (over LM7 cam) at 2,500 -4 lb-ft
3,500 0
4,500 +4 lb-ft
5,500 +9 lb-ft (10 hp)
6,200 +12 lb-ft (14 hp)

LS7 vs. LM7 (Plus Rockers)

With the highest lift and longest duration of any factory cam, it was not surprising that the LS7 offered the greatest power gains. Since the LS7 was designed to be run with 1.8 rockers, we ran the cam both ways. Equipped with 1.7 rockers, the LS7 cam increased peak power from 353 hp and 384 lb-ft to 422 hp and 395 lb-ft. Up to 4,500 rpm, the LM7 offered more power, but the LS7 pulled strong all the way to 6,500 rpm. Installation of the 1.8 bolt-in aluminum roller rockers from Crane increased peak power by another 10–12 hp but resulted in an earlier valve-float point. Adding dual-springs would solve that problem.

Engine Designation: LS7

Displacement 7.0L
Lift 0.558/0.558 w/1.7:1-0.591/0.59 w/1.8:1
Duration 211/230 degrees
LSA 121 degrees
Idle vacuum 19.6 in-Hg
Cranking Compression 162 psi
Peak Power 422 at 6,300 rpm
Peak Torque 395 at 5,000 rpm
Average HP 300
Average TQ 361
HP/TQ gains (over LM7 cam) at 2,500 -40 lb-ft
3,500 -19 lb-ft
4,500 0
5,500 +51 lb-ft (53 hp)
6,500 +92 lb-ft (115 hp)


LS9 vs. LM7

Given the similarity in specs, it is not surprising that the power curve offered by the LS9 mimicked that of the LS7 with 1.7 rockers. The LS7 offered slightly more peak power, but only slightly. We did not run the LS9 with 1.8 rockers, as the LS9 was factory-equipped with 1.7 LS3-based rockers. Equipped with the LS9 cam, the 5.3L produced 420 hp and 393 lb-ft of torque. Note that peak torque production never varied by more than 15 lb-ft with any of the factory cams; the duration simply shifted the torque curve higher or lower in the rev range. Whereas the LM7 produced peak torque at just 4,300 rpm, the LS7 and LS9 cams produced peak torque 700–800 rpm higher.

Engine Designation: LS9

Displacement 6.2L
Lift 0.558/0.562
Duration 211/230 degrees
LSA 122.5 degrees
Idle vacuum 20.1 in-Hg
Cranking Compression 163 psi
Peak Power 420 at 6,200 rpm
Peak Torque 393 at 5,100 rpm
Average HP 303
Average TQ 360
HP/TQ Gains (Over LM7 cam) at 2,500 -41 lb-ft
3,500 -20 lb-ft
4,500 -2 lb-ft
5,500 +51 lb-ft (53 hp)
6,500 +90 lb-ft (112 hp)

By Richard Holdener
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1 comments
gallonoffuel
gallonoffuel

I know this is an old article but the data you have for LS6 is wrong. That whole table is a copy of the LQ9 table, and is very low in cam specs and I predict its also low for the power output based on previous research. 

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