GM Performance Parts LSX 454 - Is Everything Bigger In Texas?

The next dyno test left all variables the same, but replaced the stock LS7 intake manifold with one that was hand-ported by Jeremy Formato at FasterProms (PN, LS7 Port, Retail $300). Formato notes, "The LS7 intake flows tremendous in stock form, but by enlarging the intake ports and taking out factory deviations, such as casting lines behind the throttle body opening, the ported intake will provide greater airflow."

When the results came in from the ported intake, the engine made 692.1 horsepower at 6,700 rpm with 611.7 lb-ft of torque at 5,200. Not only did the ported intake gain 12.3 horsepower with 7.5 lb-ft of torque at the peaks, but the gains were consistent across the entire dyno-pull range.

Next, Precision Race Components' (TSP's affiliate company) ported LS7 heads (PN 199-265LS7, Retail $1,899 a pair) were bolted on. On-site CNC porting increased intake flow from 359 to 402 cfm (at 0.650 lift) and exhaust flow from 214 to 246 cfm. PRC also installed Manley titanium intake and stainless-steel exhaust valves, and performed a five-axis CNC, performance valve job.

The addition of the ported PRC LS7 heads really woke up the engine, and horsepower jumped to 718.1, a gain of 26. Torque peaked at 621.1 lb-ft, an increase of 9.3. Peak horsepower and torque were achieved at the same rpm as before the head swap and each plot on the graph is higher with the ported heads. The R&D on the PRC LS7 head is evident, as increased port size alone, without maintaining or improving port velocity, often results in decreases in torque at lower rpm. With no losses in torque and huge gains in horsepower over 5,200 rpm, the heads are showing tremendous potential.

Since the engine benefited from additional head flow, the final test would swap in a more aggressive cam. The LS7 intake was removed, along with a Meziere LS-Series electric water pump. A Quick Time Performance Quick Cam two-piece timing cover was utilized so that cam swaps could be done on the dyno without having to remove the crank dampener and pulley, which in this case was an optional PowerBond Race Series SFI-approved 10 percent underdrive balancer pulley (PN 25-PBU1480-SS10, Retail $199).