As discussed in Part 1 of this story in our last issue, '04 GTOs are being resold at bargain prices right now. The opportunity that this affords the industrious Pontiac speed demon is that he can buy a GTO for little coin and use the excess cash for upgrades.
Case in point is Vortech's new '04 GTO supercharger system, PN 4GJ218-018SQ, that adds well over 100 hp at the rear wheels and is emissions compliant in all 50 states (certification pending at press time). It has a suggested retail price of $5,950.95 (or $5,686.95 unpolished) and can be installed in a weekend. Sure, normally $5,700- $6,000 for a single upgrade would be a tough nut to crack, but with Goat prices as low as they are, all of a sudden it's well within the realm of possibility. And with that kind of power injection, the GTO will have nothing to apologize for on the street.
In Part 1 of this story we introduced you to Vortech's new kit, took you inside the V-2 SQ S-Trim supercharger and began the installation. Certain engine parts like the airbox, inlet ducting, engine covers, passenger-side coil mounts, and the harmonic balancer were removed to make way for the supercharger and its associated kit components. The balancer was replaced with an upgraded SFI-approved unit that featured the correct pulley arrangement, which was included with the supercharger system. Coil spacers were installed on the passenger side, the clutch slave cylinder was moved, an oil-filter adapter was added, and the supercharger's oiling system was plumbed. A set of 42 lb/hr injectors were added as was a new power steering pump pulley and supercharger bracket. Then the V-2 SQ S-Trim supercharger was bolted in, followed by the air ducting, the Gilmer belt, the air filter system, the flex hoses, and the MAF. The power steering fluid tank was relocated to make way for the Vortech aftercooler (read Power Cooler). With the Power Cooler installed, the primary and secondary discharge tubes were then mounted.
For this issue we will pickup the installation where we left off and then dyno test the GTO to gauge the improvement. So come along for the ride and see what 7 pounds of boost from a Vortech can do for your GTO.
Dyno Testing And Driving Impressions
Before the addition of the Vortech centrifugal supercharger, we recorded naturally aspirated baseline outputs of 244.4 hp and 262.9 lb-ft on the Vortech Mustang chassis dyno. Though the test car showed only 2,202 miles on the odometer, these numbers are a bit lower when compared to other stock six-speed GTOs we've seen tested on the brutally honest Mustang treadmill.
After the Vortech installation, we wanted to make sure we got real-world test results and didn't get caught up in the heat-soak controversy that's plagued some GTO supercharger tests of late. Immediately after the final bolt was tightened and the reservoir filled with 2 gallons of room-temperature coolant, the GTO was strapped to the rollers and given a 5-minute warm-up period. The best reading was 364.1 hp at 5,800 rpm and 359.3 lb-ft at 4,750 rpm (chart shown).
To make sure the gain wasn't a fluke or due to the dead-cold engine, we took the car on a 15-mile thrash to get everything up to normal operating temperature, and most importantly, to make certain a true representation of boost effectiveness could be measured.
During the warm-up loop, the extra power was easy to feel and hear, and the Vortech produced a neat whine under boost. Though rain prevented much gear ripping or truly hard launches, it was easy to feel the added urge at just about any throttle position above idle. As the accompanying dyno chart shows, the Vortech increased peak torque output by 96.4 lb-ft and moved the peak torque point from 2,650 rpm stock right up to 4,750 rpm, a detail that gives the car excellent midrange capabilities. On one stretch we were doing 110 mph before we knew it.
After the heat-soak loop we drove the GTO directly onto the rollers and recorded 346.6 hp at 6,100 rpm and 355.9 lb-ft at 4,500 rpm, the diminished output (17.5 hp, 3.4 lb-ft) proving the merit of the remote supercharger positioning and the effectiveness of the aftercooler at maintaining charge density. Granted, the weather was damp and rainy on test day and we'd predict a further drop in the 100-degree heat of an Arizona summer, but nothing that wouldn't affect any other engine in a similar fashion. The correction factor for all the dyno runs was 0.978.
Accessorizing The GTO
With dealer bargains and/or private resale, you can add a Vortech to your '04 GTO and still possibly have cash left over for some brake and rolling stock upgrades. To prove the point, Vortech accessorized the test car, and the total cost is still shy of the original $33,000 MSRP. Pontiac's loss is your gain.
