Supercharging a late model GTO
ProCharger force feeds our Goat
It really wasn’t that long ago that a 400hp street car was something special. To have that much horsepower and retain true street manners was sometimes as elusive as the mighty unicorn.
That certainly isn’t the case anymore. The big three U.S. automakers have been building cars with that much power at the flywheel for years now, and even a few trucks can produce the same results with nothing more than a dyno tune session.
The Pontiac GTO made its short comeback from 2004 to 2006, and although sales were not as aggressive as GM had hoped, they are very popular with the latest generation of hot rodders. The LS1 in the ’04 model made 350hp, while the LS2 touted 400 flywheel horsepower bone stock. We wanted to see what kind of power we could muster from the LS2 by installing Procharger’s D-1SC supercharger, all without going to an aftermarket block or rods and pistons and still run a modest amount of boost.
Our project car is a ’06 model owned by Chris Chaffin of Boise, Idaho. His car already has a few mods to the engine including a pair of LS6 heads, a mild camshaft from Livernois Performance, COMP Cams roller rockers, and a set of JBA shorty headers. We dialed in a tune with our HP Tuner’s software and strapped her to our Dyno Dynamics chassis dyno. The six-speed Goat responded with 359 rwhp, which equates to approximately 460 flywheel ponies. One thing we’ve found is that the LS engines respond very well to the right combination of parts, and this one was no exception.
Accessible Technology’s Procharger kits use top quality components, and their support is second to none. We opted to upgrade the kit from the standard P-1SC head unit to the D-1SC. It will provide more boost later, when the owner steps up with a beefier short block. All Procharger kits are intercooled, which is a huge plus when it comes to supercharging. The blower itself super-heats the air charge, sometimes as much as 100 degrees, before it enters the engine. That in itself can defeat the purpose, and cost horsepower. These ATI intercoolers drop the air charge temperature significantly, and actually help create more boost.
The GTO kit was fairly simple to install, and although tight in places, it fit like it was supposed to. All in all, the install took about 10 hours, and that included pulling the tank to install a high volume fuel pump. Performance Solutions in Boise handled the installation and dyno testing of the Pontiac as they have done the lion’s share of all the work on Chris’ Goat since the car was factory stock.
Vince at Trifecta Performance of Seattle, Washington, handled the custom tuning end and provided the ECM with just the right tune to get us what we wanted. The results? We got the supercharger to make just over nine pounds of boost and were rewarded with 522 rwhp. Just to clarify, if this car were tested on a Dynojet inertia dyno, it would have shown a tick over 570 wheel horsepower due to the difference in correction formulas. Either way, that comes out to over 650 flywheel horsepower and enough torque to move the Earth!
We can’t wait till the iron 427ci short block is finished so we can turn the wick up on the Procharger to 14 pounds and see what this force-fed Goat will dish out!