In the world of Corvettes, there's no doubt that the C6 ZR1 is the pinnacle of performance, thanks in large part to the highly acclaimed LS9 powerplant. This supercharged LS engine features 620 hp and is ready to unleash mayhem on anything that lines up next to it. The ZR1 is everything a Vette owner wants—aside from the hefty six-figure price tag that comes along with the glory. Its reign might be nearing an end, however, as Edelbrock is arming the C6 Z06 with an E-Force supercharger system. Throwing a little boost on top of the big-cube LS7 has its advantages, vaulting the Z06 past the ZR1's supercar horsepower level.
Under the hood, the Z06 packs an LS7 small-block with some of the wildest features ever included in a production vehicle. It was the first production Corvette to utilize a dry-sump oiling system and titanium connecting rods. It breathes easily through a killer set of aluminum cylinder heads, and its roar comes from 427 ci. Howard Tanner of Redline Motorsports says a typical Z06 will throw down 450 rwhp and 427 lb-ft of torque on the company's in-house chassis dyno. As a comparison, the late-model ZR1 cranks out a stellar 535 rwhp and 525 rwtq on the same chassis dyno. Add the Edelbrock E-Force and the story changes, as a boost-tickled LS7 will far exceed its LS9 sibling's output—especially when the test subject benefits from a Redline Motorsports Stage III package.
Tanner and Redline are no strangers to Corvette performance, as the Schenectady, New York, shop is a booming facility that churns out big-power Vettes and other LS-powered GM vehicles on a regular basis. He offered up a C6 Z06 belonging to longtime customer Bonnie Jones as a test mule for the Edelbrock blower. Her '09 Z06 produced 541 rwhp and 520 rwtq with the aforementioned Stage III setup. It includes Kooks long-tube headers, a catted X crossover pipe, a custom Redline Motorsport camshaft, and a Vararam intake. Naturally, the ECU contains a custom program by Tanner. Jones' Vette sees a lot of action on the streets, and the Edelbrock blower was exactly the kind of extra power she was seeking.
Edelbrock started with a clean slate when designing the LS7 supercharger system. The only holdover was the use of the Eaton TVS 2300 supercharger rotors. The unit has the same internals as the LS9 supercharger, but Edelbrock has done some things differently.
According to Edelbrock's head supercharger designer, Rob Simons, the company designed and cast a completely new manifold specifically for the LS7 cylinder heads. It features long runners, as opposed to an open plenum design, to help promote low-end torque and throttle response. The supercharger features a large intercooler and still fits under the factory hood. One unique feature we like is that Edelbrock includes a ZR1 liquid-to-liquid oil cooler to replace the front-mounted LS7 air-to-liquid oil cooler. It's a more efficient design and allows a large heat exchanger for the supercharger's intercooler to be mounted in the front. This helps cool off the intercooler water and keep inlet-air temps at bay.
The supercharger comes assembled and nearly ready to bolt onto the car. The accessories—specifically, the heat exchanger, water pump, fuel injectors, and oil cooler—took some time to add, but the only major modification was pinning the crankshaft. Thankfully, Redline performs this procedure on a weekly basis, and head technician Bruce Hotaling handled it easily. Pinning the crank allows the blower pulley to lock onto the crank snout. (The stock balancer is pressed on, instead of using pins or a keyway.) Without this modification, the power needed to turn the supercharger will cause the pulley to spin on the end of the crank. Adding a keyway is impossible to do without removing the crankshaft, so pinning it is the only option.
Once Hotaling was finished under the hood, it was time for Tanner to step in and start tuning the car. Using EFI Live, his major adjustment was to run the Lambda air/fuel ratio at 11.5:1 and adjust the ignition timing.
"We run it a little richer because of the instant boost of the E-Force. It helps the cooling factor, due to the higher compression of the LS7," he says. He used a ramp-in strategy for the ignition timing curve that started with just 12 degrees down low and 17 degrees at redline.
The E-Force produced a maximum reading of 8 psi at 6,400 rpm, resulting in a peak output of 632 rwhp—some 92 rwhp better than naturally aspirated trim. The results were obtained on 93-octane pump fuel.
"Most Eaton TVS 2300 kits have an aggressive boost curve up front and then tail off, whereas the E-Force design produces a flatter curve and the boost peaks toward the end," says Tanner. If you're looking to bolt the E-Force onto a stock or near-stock LS7, you can expect to see 565 rwhp on 91-octane. Those are out-of-the-box power numbers, too, using the Edelbrock-supplied ECU tune.
For now, keep an eye out for Jones and her yellow Z06, because it packs serious power—and she knows how to bang gears better than most guys.