Now that East Coast Supercharging has equipped Project LS1 with the Procharger P-1SC-1, an ATI balancer from Thunder Racing, and all of the relocated stock equipment, it was time to wrap things up. The standard 3.5-inch twin high-flow intercoolers were included in the kit as was a Diablo Sport tuner; however, Procharger had just finished developing a 4.5-inch intercooler upgrade that we were dying to get our grubby little hands on. We tested the kit as-is, then installed the new intercoolers and a custom tune from East Coast Supercharging into our Trans Am to see how much more power was to be had.
However, a simple track and dyno test wouldn't be sufficient this go around. The only thing we like at GMHTP more than $10 hookers and huffing Krylon is heavy tech (Editor's Note: the views expressed by Scott Parker do necessarily reflect those of the GM High-Tech Performance staff), and Procharger was happy to accommodate us (with the tech that is). President Dan Jones of ATI Procharger shipped us not only a bunch of testing equipment, but one of his engineers, too. With the help of Product Development Engineer Ryan Bosch and his testing equipment, we could compare the intake air temperature and pressure drop from the 3.5 and 4.5-inch intercoolers.
Before testing, there were still a few loose ends that needed to be tied up. The intercoolers needed to be bolted up with the plumbing connecting it to the blower and the airbox. In order to match the enormous increase in airflow, the stock 26-pound injectors would need to be upgraded to the 38-pound units supplied in the kit along with a new in-line fuel pump. The spark plugs would need to be taken two steps colder, so ECS supplied us with a set of NGK TR6s.Follow along for the remainder of our LS1 Procharger install and testing at the East Coast Supercharging facilities in Cream Ridge, New Jersey. As mentioned in Part I, this will be Project LS1's swan song, and we had every intention of taking one last trip down the 1320 without performing a coup de grace on the stock 10-bolt. So for the final drag test we returned to our home away from home Englishtown Raceway Park for a few hits on the Mickey Thompson drag radials.
It is no secret that intercoolers are the most effective and safe way of resisting detonation in blower motors, plus they offer the opportunity to increase boost--and horsepower. In high-compression applications such as Gen III motors, this becomes even more important. In fact, Procharger says that with the stock 10.1:1 compression the Gen III LS1 can handle very little boost on pump gas safely. This is precisely why its kits are only available with twin high flow intercoolers.
Since detonation is such a concern, Procharger opts for bar-and-plate-style intercoolers, which owner Dan Jones says is the most effective type of air-to-air intercooler. "It allows more pathway for air and the flow path becomes more effective, even though pressure drop is slightly higher than an extruded tube intercooler. By favoring effectiveness the decrease in temperature over other companies allows an increase in ignition timing that will make up for the loss of pressure."
Procharger's latest manifestation of this philosophy is a new intercooler upgrade option, which adds an inch of width to the twin high flows, now totaling 4.5 inches. Now, you might think that increasing the overall size would increase the amount of boost drop-off from routing the charged air through these babies, but that is not the case. In fact, since the passageway in which the air moves in and out of the intercooler increases, so does the boost. And that increases the effectiveness of the cooling. "If we just increased the depth then this would not be the case, however we made the intercoolers deep enough to begin with and adding width helped achieve more flow," Dan said.
Dyno and Track Numbers Explained
In the past few installments of our Project LS1 series, changing the torque converter and switching dynos has resulted in varying power readings. The naturally aspirated peak of 347.4 horses and 347.1 lb-ft of torque came after SLP's long-tube headers, exhaust, and LS6 intake. Soon afterward, the stock converter was swapped for a 3,500-stall TCI Super StreetFighter, which dropped our ETs from 12.85 to 12.36. After the converter was installed, the dyno horsepower never quite measured up to its former peak, even after a few more mods.
Due to variations between dynos and because we wanted a true back-to-back comparison, we re-baselined our Trans Am on ECS's Mustang dyno before the Procharger went on. ECS prefers to leave the torque converter unlocked while dyno testing, and the numbers came in at 301.5 horses and 348.9 lb-ft. On the same dyno with the converter unlocked, the Procharger with the larger intercoolers and some PCM fine-tuning netted 421.4 hp and 405.8 lb-ft of torque. While this 119.9-hp gain represents a 40 percent increase in power over stock, locking up the converter or doing this test on a six-speed LS1 would have put the power gains more in the ballpark of Procharger's advertised 50-55 percent range.
GMHTP tested this T/A's new converter in March 2004, and 54-degree weather and low humidity allowed us to break into the 12.3s on drag radials. This was a great ET for the mods, but most of the time the car ran 12.4s and 12.5s.The weather at Jersey's Raceway Park wasn't nearly as accommodating when we tested the Procharger kit. Seventy-degree temps and high humidity no doubt affected the supercharger's performance, yet the T/A still managed an 11.5 at 116 and change. Owner Heath is very happy with his Pontiac's power boost on the street and at the track, and reports an awesome seat of the pants feel with only a slightly higher coolant temperature seen on 90-degree-plus days.
Dan went on to say that the beauty of this intercooler upgrade is "it gives added insurance against detonation in areas where only lower octane fuel is available, and it gives the ability to upgrade the motor and add boost. Since our blowers are rated at much higher than they are used with the base kit, you can just crank up the boost or feed a bigger motor, and the intercooler will still maintain its effectiveness.