Supercharged C6 Corvettes - One Thing Leads To Another

So we were hardly surprised to find that Andy Green of A&A Corvette Performance went through some wheelin' and dealin', plus some serious motor massaging, to fully realize the potential of his '06 C6 "Grand Sport."

"I've always liked [the Grand Sport] color scheme," Green explains. "But the original version was down on power, and I knew I could fix that." Fix indeed, since by the time he was done breathing on the engine bay, he had 735 ponies pounding the pavement.

It wasn't just about power, though. "I thought an '06 C6 would serve as sort of a 10th anniversary tribute to the original '96 edition," he adds.

Green eventually unwrapped five blowers-count 'em, five-to see what sort of power he could pull out of the LS3. Along the way, he experimented with a couple of camshafts and two different diff ratios, before finally settling on a 2.73. He also modified the exhaust four times before arriving at the current setup (a 3-inch B&B Fusion), along with bolting on Brembo brakes and Pfadt coilovers.

Still not satisfied, he later switched to an Si-trim head unit on the car. That's because Green is fanatical about forced induction, making sure he squeezes out every bit of boost from his blower setups. As part of that process, he's figured out how to optimize the efficiency of the airflow. More about that in a moment, but first, a note on how this obsession with continuous improvement got started.

About nine years ago, and 10 Corvettes earlier in his personal collection, Green invented a simple little part called a Frame Saver. He hated scraping the nose of his C5 on a steep driveway or speed bump, so he welded up some brackets with casters on them and ran a small ad in the back of VETTE magazine. (Enterprising entrepreneurs take note: you too can become an overnight success, just by advertising in this magazine!).

One of his Frame Saver customers came into the shop complaining about the slipping belt of his blower (not a Vortech unit, though), plus some overheating issues. Green stared intently at the installation for a moment, and then a light went on. By adding an extra idler pulley, and moving the tensioner over a bit, the problem could be solved-almost. He also saw how much the airflow to the radiator was blocked, so he laid it down at an angle and relocated a couple other obstructions.

The customer was so happy, word of mouth prompted even more guys to show up at Green's shop to sort out their super-charger woes. Today, Green has more work than he can handle, but he's not complaining. He installs more than 100 superchargers per year, and ships out three times that number in mail orders. And business has never slowed, even in a sluggish economy.

Green's approach emphasizes improving airflow management (for both the charge air and the ambient cooling air), along with custom tuning and a few other mods. Cooler air in a supercharger is especially important, as it improves efficiency with less risk of detonation on pump gas, allowing higher boost levels. Green points out that the positioning of the intercooler is critical, since a large intercooler located behind the frame is not as efficient as a smaller intercooler exposed to full frontal airflow. So A&A not only uses a larger intercooler, but also forces more cooling air through its core by means of a ram-air system. It scoops cooling air from under the front fascia and guides it directly into the intercooler.

Lastly, since a slipping belt can reduce supercharger efficiency (recall Green's first blower customer), A&A has developed a bracket system with more wrap for additional surface contact.

Getting back to his yellow C6 testbed, in addition to all the mechanical change-outs, Green also threw on some Z06 fenders and a grille. But he admits that the latter item wasn't so much for airflow as for improved looks.

Green installed a set of 9.5:1, 22cc dished Diamond forged pistons, along with his own custom blower cam (228/236 degrees of duration and 116 degrees of lobe separation). In addition to a new Vortech centrifugal supercharger, he refined the install with some trick-looking constant-tension clamps, an eight-rib belt, and American Racing headers, and then backed up the powerplant with an ACT clutch. Pfadt coilovers and sway bars settled down the chassis, and Wilwood's big-brake kit brings it to a sudden stop. He also modified the mufflers by inserting straight-through pipes, and threw on a set of '09 "Spider" wheels and Nitto rubber (275/35R18s up front and 335/30R19s in the rear).

Now that he's done, everyone thinks Green has some kind of special-edition mystery Corvette. And he likes it that way, keeping people off balance and not revealing all his secrets. But don't expect him to leave well enough alone, since he has even more plans for revamping his Vettes.