THERE'S AN UNDENIABLE allure to a supercharger. The debate over whether to go normally aspirated or forced induction in building power is a worthy one, but the academic reasons often fall to the simple fact that a blower is cool.
Blowers look cool, and they certainly sound cool, and with the benefits of modern tuning-and the fact that modern Corvettes have never been better equipped to handle them-they're relatively efficient tools for making big horsepower in an otherwise stock vehicle.
We've seen plenty of Roots-type blower systems on C5 and C6 Corvettes, most of them versions of MagnaCharger kits, but comparatively few centrifugal blowers. So when we had the opportunity to follow the installation of a Vortech-based, intercooled system from Oxnard, California's A&A Corvette, we loaded up our camera gear and camped out at Detroit-area tuning shop Stenod Performance for the wrench-turning session.
"We were impressed with the kit," says Stenod's Joe Borschke. "From our experience installing and tuning it, it seems like a good value for our customers."
Although Vortech offers a specific, intercooled kit for the C6, A&A's system is priced approximately $1,800 lower. Differences between the two include things like fuel injectors and A&A's inclusion of a Kenne Bell Boost-A-Pump for the fuel system, but the biggest differentiator is tuning software. Vortech's C6 kit includes a plug-in programmer, while the A&A kit does not.
"We don't believe in a pre-programmed tune," says A&A's Steve Padfield. "Each project is unique, so we believe it's best to have a custom tune performed at the time of installation."
Of course, that presupposes a qualified tuner is available in a customer's area. But assuming one is, it's definitely the method that ensures optimal performance. In the case of our project, additional engine modifications necessitated a custom tune that would have rendered a pre-programmed calibration unusable anyway.
The test vehicle for this story was an '05 automatic with a mere 4,000 miles on the odometer. Like all '05 models, it features a 6.0L LS2 rated at 400 hp and 400 lb-ft of torque.
As with any intercooled system for a late-model Corvette, the installation involved removing the front bumper cover to provide room for the heat exchanger and related plumbing. Generally speaking, the kit was well engineered and used first-class materials. Kevin Gluski, the installer at Stenod Performance, found some of the instructions in the downloadable assembly manual to be a bit vague, but the overall impression on the fit and finish was one of admirable quality.
That's not to say the project wasn't without its difficulties. Regardless of whose kit is used, stuffing an intercooled supercharger system into the tight confines of a Corvette's nose isn't easy. Care must be taken to ensure adequate clearance for a variety of hoses, tubes, electrical lines, and more. There are a few other details worth mentioning:
Like all late-model, LS-engine vehicles, the precaution of "pinning" the crankshaft is necessary, because the balancer is press-fitted to the crank hub. Pinning the crank involves drilling a hole or two between the balancer and crank, and inserting a dowel-type pin to provide a simple lock between them. This prevents unwanted slippage that could occur under the greater load imposed by the supercharger.
Pinning the crankshaft requires the removal of the steering rack, which includes holding the steering wheel in place to ensure it aligns perfectly when the rack is re-installed. Otherwise, driveability will suffer, and the rack will likely need to be removed again to correct the problem. Reinstallation of the steering rack automatically means a trip to the alignment shop, too.
Finally, the routing of the plumbing between the blower, the intercooler, and the engine requires the permanent removal of the factory power-steering cooler. A&A Corvette says only hard-core road racers in hot climates should notice a difference in performance, and that the average street enthusiasts shouldn't have a problem.
A lift and the tools typically found in a house-sized Snap-on chest make the job easier, but after watching Stenod Performance work on the car for a couple of days, it seems like a job best left to professionals.
Of course, there's more to the installation than just the blower's head unit, the intercooler's heat exchanger, and the hoses that connect them to the engine. The fuel system is upgraded, too, with higher-capacity fuel injectors and the electronically controlled fuel-pump "amplifier" in the Boost-A-Pump from Kenne Bell. It maximizes the output of the factory fuel pump without the need to drop the tank and replace it with a higher-volume unit. Also, the kit's intercooler is a simple, air-to-air design, rather than a liquid-to-air air design that requires a dedicated coolant supply, an electric water pump, and complementing wiring upgrades.
Before we divulge the chassis-dyno results of the project, we should address a couple of points: First, as we mentioned early in the story, this Corvette received additional engine mods that included a blower-spec camshaft (also from A&A Corvette), a set of L92 cylinder heads and an LS3 intake manifold, Dynatech long-tube headers, and a Corsa exhaust system. So the engine was already set up for deeper breathing capabilities than in its stock configuration. The mods were smart additions, however, as they better exploited the pressurized air that would be crammed through the throttle body.
Stenod Performance took care of the specific tuning calibration for the combination; it was designed for pump gas and the system's approximately 10-pound boost level. The other thing to note is that it's always difficult to get a good, accurate chassis dyno reading with an automatic-transmission car, as the electronically controlled lock-up design of GM's modern automatics doesn't allow for full run-outs on the rollers. That said, the newly blown Vette put down 508 hp and 439 lb-ft to the tires, or roughly 600 hp/520 lb-ft at the crank. The numbers represent a power increase of more than 50 percent, along with nearly 33 percent more torque over the baseline test.
The heads, cam, and exhaust system definitely contribute to the performance gain, with the heads and intake essentially bringing the engine to LS3 specs and enabling a greater rev range. Nevertheless, we were surprised by the dyno results. They were terrific for a combination using all bolt-on or off-the-shelf components.
Subtracting the cam-and-heads part of the job, the blower, installation labor, and dyno tuning cost the Corvette's owner, Mike Lucas, about $7,700. That's about average in our experience and represents good value in a performance-to-dollar evaluation. The accompanying photos provide an overview of the major steps involved in the installation process.
To paraphrase a popular advertising line: Supercharger kit: $5,200. Installation labor and tuning: $2,500. The sound of a fully wound supercharger as you leave a trail of F1 Supercar residue on the pavement: Priceless.