 The center section (lower...  The center section (lower plenum) of the manifold is placed into the lower section. VMax Motorsports' Pete Incaudo points out that the sealing surface directly behind the 90mm throttle body opening is challenging to seal, from a manufacturing standpoint. |  The center section contains...  The center section contains the lower portion of the intake runners. Incaudo notes that the upper section seals to the lower plenum between each intake runner. Any mismatch at these sealing junctions results in minor variations in port flow from one runner to another. |  The upper plenum or top section...  The upper plenum or top section of the manifold has a sealing surface corresponding to the previously shown lower section. |
 During production, the upper...  During production, the upper section is vibration welded to the lower. Aftermarket three-piece manifolds, meanwhile, use a traditional O-ring-type gasket and fasteners for sealing. The resulting removable top section allows additional porting access to engine builders. |  A cutaway of the front section...  A cutaway of the front section of the intake runner reveals the joining line between the upper and lower plenum sections. Since this press fit is not welded together, it's susceptible to a small amount of leaking. This leakage results in a reduced transfer of air to the cylinders. |  Since the manifold's internal...  Since the manifold's internal sealing is virtually impossible to address, VMax came up with a porting program designed to flow more air. The runners are shaped using 1/2-inch and 3/8-inch carbide cutters and polished with 60- and 240-grit roll sandpaper. Porting is accomplished using a Dumore straight-handle grinder. |
 A close look reveals that...  A close look reveals that in addition to the material removed from the intake port, the top and bottom of the runner entrances have also received a significant rework. Note how the manifold joins in the runner. |  On average, the initial port...  On average, the initial port width on a stock LS2 manifold averaged 0.94 inches, while the ported LS2 manifold averaged 1.051. As shown on the ported manifold, this center port measured 1.0455 inches. |  After completing the intake...  After completing the intake porting and carefully replicating the porting template, attention turns to the 90mm throttle-body opening. The focus here is on the floor and roof, allowing the air to transition to the runners more smoothly. A careful measurement of the area directly behind the opening indicated that it was increased from 91.6mm to 94.8mm by the rework. |
 Dyno testing was done on Real...  Dyno testing was done on Real Performance Motorsports' (Lewisville, Texas) Dynojet 248C chassis dynamometer. Our stock, manual-trans C6 registered a peak-hp figure of 345.6, with torque cresting at 342.9 lb-ft. (All figures are SAE.) Average hp and torque from 3,100-6,100 rpm were 286.5 and 328.2, respectively. |  After swapping out the intake...  After swapping out the intake for the ported unit, the C6 delivered peak readings of 355.8 hp and 352.1 lb-ft, for gains of 10.2 with 9.2, respectively. In addition to the peak gains, average hp increased by 8.2 (up to 294.7), while torque jumped 9.2 lb-ft (to 337.4). |  A comparison of stock versus...  A comparison of stock versus ported-intake hp highlights the effectiveness of the port work. Gains as high as 13.6 hp (and, though not shown here, 13.7 lb-ft) were registered at 5,200 rpm. Even more telling are the double-digit hp improvements at each 100-rpm increment from 4,900 through 5,800. |
Conclusion
All told, VMax's intake-porting regimen resulted in increases of 10 rwhp and 9 rwtq, all for only $300. Even better, most enthusiasts can perform the swap at home in less than an hour. Best of all, the ported manifold is completely stock-appearing and will fly under the radar of fellow enthusiasts...as well as the dealership.
"I am really impressed by the additional power gains that the ported manifold provides," says car owner Tammi Douglas. "The car feels more responsive around town as well as in the upper rpm range. Knowing that the manifold isn't restricting performance gives me confidence that additional modifications will yield results without having to invest in an aftermarket [unit]."
For C6 Z06 owners, VMax has been hard at work on a porting program for the LS7 intake. In fact, a fully ported LS7 unit should be available by the time you read this. For the stock-appearance purist looking for additional performance or anyone intent on having the most powerful C6 around, the need to purchase an aftermarket manifold just became less acute.
| Dyno | HP | HP Avg. | Torque | TQ Avg. | A/F Avg. |
| Baseline | 345.6 | 286.5 | 342.9 | 328.2 | 12.9 |
| Ported LS2 | 355.8 | 294.7 | 352.1 | 337.4 | 12.8 |
| Increase | 10.2 | 8.2 | 9.2 | 9.2 | NA |