Last month we showed what gains were available from three aftermarket Three-Valve intake manifolds in naturally aspirated trim. This month we're going to try the same three intakes, only now we'll see what the C&L, FRPP, and JPC intakes can do with a little boost behind them.
We headed back to Boca Raton, Florida, where the crew at Blow-By Racing was buttoning up the engine install on the '06 GT of Jillian Gastright. The new combination consisted of a BBR-built 302ci modular short-block, stock Three-Valve heads, BBR Stage 2 cams (which are locked out), and a TR-6060 six-speed transmission. Boost comes from a Vortech T-trim centrifugal supercharger, which is pullied for about 18 pounds of boost.
Looking for big power, Chris Jones, owner of BBR, went to work tuning the GT with the stock intake manifold. As the test got underway, we realized we couldn't perform the test the same way we did with the NA S197. The ignition timing was the same in every run in the previous test, which made for a great apple-to-apples comparison. But this time, we adjusted timing to optimize each combo. Each manifold performed differently with only slight timing changes. We still made sure the ambient temperature and the water temperature remained as close to the same as possible.
When the tuning with the stock intake was complete, the combination laid down 645 rwhp and 543 lb-ft of torque with 17 degrees of total timing. These numbers are pretty stout, and we were excited to see what difference the aftermarket intakes would make.
As the test went on, we discovered the unported stock heads were likely a restriction, and the addition of ported heads would make the gains from each of the intake manifolds significantly larger. In a high- horsepower combination like this, every car is different, and will react differently to modifications such as manifold changes.
C&L Performance PN 720
The C&L Performance Three-Valve intake manifold was designed to work well in numerous combinations. Its cast aluminum construction makes it great for boost (or nitrous), as it can handle loads of pressure without any fear of ballooning or breaking. Its 10.25-inch long-runners give you a great combination of low-end torque and mid-range power, which is great in cars that see mostly street time. The C&L intake is also a great race option, as it can hold as much boost as you can throw at it, and if you ice the intake, the aluminum will hold the cold long enough to make the incoming air denser for more power potential, but only in very short increments of time.
The C&L was the first intake installed on Gastright's '06 GT. Given that the C&L intake has the longest runners of the group, we expected to see the least amount loss down low, and good gains up top. With these expectations in mind, Jones went to work on the tune.
The timing and fuel changes were handled with SCT software, and when Jones was finished with initial tune, the S197 laid down 649 rwhp and 561 lb-ft of torque, but looking at the amount of timing and the air/fuel curve (on the rich side) we knew there was more. After about a half dozen pulls with more power, Jones found the sweet spot and was not able to make any more power. With the timing set at 18 degrees, the end result was 658 rwhp and 572 lb-ft of torque, giving us a peak gain of 13 rwhp and 29 lb-ft of torque.
Below the peak, power and torque were nearly identical until 4,000 rpm, only losing about 5hp and 10 lb-ft of torque between 3,000 and 3,5000 rpm. Between 4,000 and 4,600 rpm, power and torque was up by as much at 22hp and 18 lb-ft of torque. From 5,000 rpm to redline, the C&L intake pulled away from the stock intake, quickly gaining about 15 hp and 15 lb-ft of torque and carrying it till the end of the run. Given the gains over stock, the C&L Performance intake manifold is a great street or race option.