We wanted to know how an aftermarket cam of equal (or near-equal) duration compared with the stock stuff. Check out the results to see how your favorite cam compared with the factory LM7.

Baseline: 5.3L LM7 Cam Being such a diminutive factory cam, it is not surprising that power fell off so rapidly past 5,500 rpm.

The LM7 cam offered more low-speed torque (by as much as 22 lb-ft) up to 4,400 rpm, but the LS1 cam pulled away there after.

Such is the effect of extra duration, as the LM7 cam was designed to build torque in the 5.3L.

The LS1 cam would certainly offer additional performance if you kept the revs above 4,000 rpm, but know that below that point there was a torque loss.

LS Engine Designation: LS1 (’98–’00)The odd thing about the LS2 test was that this was the only factory cam with which we experienced valve float.

Credit the Holley Dominator EFI system for the ability to accept and tune all of the different cam profiles.

While we were on factory cams, we decided that in addition to the peak power gains, it would be interesting to document things like idle vacuum, cranking compression, and average power and torque gains lower in the rev range.

Run on the high-mileage 5.3L, the stock 5.3L cam produced peak numbers of 353 hp at 5,200 rpm and 384 lb-ft of torque at 4,300 rpm.

It is interesting to note that the same cam was used on the smaller LR4 4.8L, and that combination (same heads, cam, and intake) makes peak power 300 rpm higher.

Obviously tuned for low-speed power, torque production with the stock cam exceeded 350 lb-ft from 2,700 rpm to 5,300 rpm.

We tested the LR4 and LQ4 cams, but these produced identical power to the LM7. LM7Measured out at 6,500 rpm, the early LS1 cam offered 63 hp over the LM7 cam, but the results illustrate that the gains did not come without a trade-off.

The LS2 also required a front cam sensor (no provision on the cam for rear sensor), but the LS1 and all other (early) three-bolt cams required a rear sensor.