It's a question as old as the automobile itself: How much horsepower isenough, and can you ever have too much?
The answer to that question is usually another question: Well, how areyou going to use it? To a Top Fuel pilot in the NHRA, "enough"horsepower is measured in the thousands. In a shifter kart, 35 hp willthrill you.
We're guessing your power needs fall somewhere between those extremes.Yet, to properly set up your car, the question still applies--how (orwhere) will you use your Corvette? Street, track, some of both? Or areyou looking for bragging rights at your local shop's dyno day?
For the two C5s that appear in this special "Undercover Speed" section,the magic number is 500 hp, or close to it. That represents asignificant increase over what a stock LS1 or LS6 puts out, somethingyou can really feel pinning you back in your seat as you nail thethrottle. Yet 500 horses aren't so hairy as to be temperamental on thestreet. That last word is important. Both the yellow '02 seen here andthe silver '04 Z06 in the story "All Motor" elsewhere in this section(p. 18) are primarily street-driven cars. This '02, in fact, is a dailydriver. But the owner sees just enough track time, and maybe a stoplightdrag or two (though he won't outright admit it), to need some extrapunch when the situation calls for it. (In typical street sleeperfashion, the owner has requested anonymity to maintain his competitiveedge.)
Reaching the 500-horse mark can be done several ways: heads and cam,increased displacement, forced induction, or some combination of allthree. In the case of this car, a supercharger was the answer.Specifically, this Vette breathes deep, courtesy of a Magnuson MagnaCharger.
The Magna Charger is a Roots-type blower. On top of the engine is acase, within which spin two rotors that are driven off the crankshaft.These rotors pressurize the air coming from the intake and push it intothe combustion chambers. More air, when matched with more fuel,increases the engine's volumetric efficiency and will make more powerthan the air/fuel charge under normal atmos-pheric pressure. In the caseof the Mag-nuson unit, the company claims its supercharger is worth anincrease of 130 rwhp.
One unwanted byproduct of the supercharging process is heat. Forcing airthrough the case and into the engine heats up the incoming charge,making it less dense (and therefore less efficient). To combat this heatgeneration, Magnuson has combined its twin-screw blower with anair-to-liquid heat exchanger--an intercooler--that's integrated into theintake manifold below the blower. While the 'cooler does provideunderhood heat relief, it also makes the whole supercharger package tallenough to require the use of an aftermarket hood. As it turns out, thebulging RKSport hood is the only clue that something unusual lurkswithin this yellow stealth bomber. Well, that and the titanium Z06exhaust peeking out the rear.
A&A Corvette Performance in Oxnard, Cali- fornia, installed the MagnaCharger on the yellow Vette. The blower, 48-lb/hr fuel injectors, and aGriffin aluminum radiator were the only modifications made under thehood--well, the only mods our stealth pilot would admit to, anyway. Hedid say that Unitrax in Anaheim, California, helped set up the Vette'srearend, and that he put a Yank 2,600-rpm-stall converter with lockup inthe driveline.
The combination worked just as our owner expected it to. In stock form,the '02 LS1 made 296 rwhp at 5,750 rpm and 292 lb-ft of torque at 5,000.With the Magna Charger and extra fuel from the fatter injectors, thatnumber grew to 443 horses at 6,000 rpm and 416 lb-ft of peak torque,which now arrives at 3,250 rpm.
Though the car's owner wouldn't tell us what he paid for themodifications made to his car, a little Internet shopping turned up apretty consistent $5,995 price for the intercooled Magna Charger. As faras bang for the buck goes, that's not bad. And, since the heads, cam,intake, and exhaust are still stock, there's plenty of power-makingpotential left in the engine, should he decide to go after biggergame--on the track, of course.