Americans have this strange fixation with “or.” Work or play? Beer or liquor? Blondes or brunettes? It turns out “and” is so much better. Why not work and have fun? Why not have a shot of Jack and chase it down with a Guinness? And why should any grown man have to choose between Scarlett Johansson and Olivia Wilde? Ridiculous! The same logic applies to power-adders. Why choose between a turbocharger and a supercharger when you can have both?
That’s exactly what Morris Malone did with his 2009 Corvette ZR1. By feeding the stock LS9 supercharger with a rear-mounted 88mm turbo, Morris has boosted his C6 up to 36 psi and 1,490 rear-wheel horsepower. With an even bigger 94mm turbo on the way, his dreams of running 205 mph in the standing half-mile is destiny in the making. Eurotrash dumb enough to rumble with this compound-boosted beast aren’t just going to eat its dust. They’re going to eat its flames.
We can already hear the haters. Rear-mount turbos suck! Just add spray and call it a day! What haters don’t realize, however, is that some people are too creative to hang out with the sheep. After throwing a standard regimen of mods at his ZR1, Morris reached the limits of the stock LS9 supercharger very quickly. “I started out with a set of American Racing headers, a smaller pulley, a Lingenfelter front supercharger snout and a ported throttle body and blower housing. Next, I installed a plate nitrous system,” Morris recalls.
Although the ZR1 ran great, he still had a craving for more power. With plans to up-jet the nitrous to 400, Morris felt it was prudent to fortify the short-block. Late Model Engines answered the call by matching up the factory LS9 block and crank with a set of Callies billet connecting rods and Diamond forged pistons. Since big boost calls for stout cylinder heads that won’t lift under pressure, Morris topped the short-block off with a set of Mast Motorsports Black Label LS3 castings. To optimize the valve events, the stock camshaft got replaced by a custom 238/254-at-0.050 hydraulic roller with 0.630/0.630-inch lift.
Right out of the gate, the new combo didn’t disappoint, laying down 1,080 rear-wheel horsepower and posting 186-mph runs through the standing half-mile. Unfortunately, Morris found himself in familiar territory once again, as upping the horsepower ante even further required another major round of mods. “I tried to up-jet the nitrous from 200 to 400, but it was hard to push any more nitrous through the motor. Ported heads, a bigger cam, and nitrous is a cookie cutter combination for these cars, but I needed more headroom for horsepower,” says Morris. “I had seen compound-boost setups done before on some factory-supercharged Mustang Cobras so I figured it would work even better on a ZR1 because it has a bigger blower. Since no one else had tried it, I thought why not?”
After sharing his plans with D3 Performance Engineering, Morris shipped his car out to the shop’s Houston facility to transform his vision of compound boost into reality. The D3 crew quickly got down to business fabricating a custom rear-mount turbo system based on a Precision 88mm Pro Mod huffer. The trick setup mounts in the space once occupied by the factory mufflers and tailpipes, then routes pressurized air to the front of the car where it plumbs back into the throttle body.
A pair of TiAL wastegates regulate the boost, dumping bypassed fumes into a big oval tailpipe shared with the turbo’s exhaust outlet. To take full advantage of the turbo’s high-rpm potential, D3 upgraded the camshaft to a 250/265-at-0.050 solid roller with 0.730/0.730-inch lift. “The ring-and-pinion options are limited in these cars, so I needed the car to turn more rpm. The engine revs to 8,500 with the new cam and turbo, so now I can take it up to 204 mph in Fourth gear,” says Morris.
Bumping up engine output by nearly 500 hp required some upgrades to the supporting hardware as well. To keep inlet air temperature cool, D3 installed its ZR1 HX heat exchanger system that includes a larger coolant core, water tank and pump. The fuel system was also enhanced with a Fore Innovations triple in-tank pump kit and Injector Dynamics 2,000cc squirters. Managing the fuel and spark is a ProEFI engine management system that features integrated anti-lag, traction control, boost control and launch control. An in-cabin knob allows turning up the boost on the fly, and the system also incorporates a Flex Fuel system that allows Morris to switch between pump gas for street driving and E98 for track duty, all without touching the laptop.
Incredibly, the bulk of the suspension and driveline is still stock. Granted that an RPM Level 7 TR6060 trans and an RPS quad-disc clutch have replaced the factory hardware, the torque tube and axles are still stock. “My first project cars were a twin-turbo Nissan 350Z and a 240SX with a built LS6. I realized pretty quickly that imports weren’t that reliable at very high power levels,” Morris recalls. “The ZR1 is a much better platform to start out with because the engine, driveline, brakes, and suspension are already set up for big power. You don’t have to redesign the entire car to go fast.
Although standing half-mile events are the ZR1’s preferred arenas of competition, Morris loves driving it on the street as well. The car’s interior has plenty of wear and tear to prove it. “I built this car for half-mile events, but it’s a fun all-around car. I love cruising the streets near Seattle where I am from and taking road trips to Las Vegas and Arizona,” Morris reports.
The true beauty of Morris’ outside-the-box approach to forced induction is that it flat-out works. In fact, the ZR1 doesn’t perform well despite its compound-boost system. It performs well because of its compound-boost system. “I’m very impressed by how linear the power is,” Morris opines. “The supercharger kicks in right off idle, then the turbo starts spooling up at 3,000 rpm and pulls hard all the way to 8,500. There’s no drop-off anywhere in the powerband.”
Words like that make you wonder why anyone would want to choose between having a turbocharger or a supercharger when you can have a turbocharger and a supercharger.