Twin-turbo Granatelli sleeper Camaro

Words And Photos: Cam Benty

When retired LA Fireman Chris Sweasey stomps on the throttle of his 2010 Camaro, a lot of things happen. For one, his gunmetal gray Camaro launches far faster than the stock exterior would ever portray. Most recently, a Hellcat Challenger learned a valuable lesson as Chris unleashed more than 650 rwhp on the unsuspecting Mopar owner, kicking a little sand in the bully’s face. It’s that kind of fun that Chris enjoys these days after years of service in Los Angeles’s most dangerous living quarters: the South Central district.

But a peek under the Camaro’s hood reveals little, as the power source of this inferno fast machine doesn’t leap out at you. Sure, there are the cool Granatelli valve covers that dress the top end of the engine, along with ruby red air inlet tubing, but there is no supercharger, either centrifugal or Roots. Even the factory exhaust manifolds are still in their stock location, and the underhood heat, so prominent in turbocharging systems, is also absent. So the question becomes — why is this Camaro so fast?

A peek at the underside reveals Sweasey’s secret weapon. Tucked up ahead of the lower exhaust tubing connection but above the frame are a pair of PTE6265 turbos and boost-regulating waste gates. Each of the turbos features a 4-inch inlet compressor, making them capable of 65 lbs/minute. The PT 46mm waste gates feature adjustable springs that allow for a range of 4.5 to 15 psi (the factory setting is 7 psi). The exhaust is 100 percent 304 stainless steel, the heat temperature-coated system delivering excellent durability. Protecting the system from ultimate disaster is a 1 x 50mm TiAL blow off valve.

In the case of Chris’ Camaro, boost adjustment has been tested on the Granatelli dyno to find out not only the capabilities of the engine, but also to make sure the stock engine, transmission, and rear end are not overtaxed. It is for this reason we did not create some smoky burnout lead photo, knowing that if those big 275 tires twist the wrong way, so could the drivetrain.

As for tuning, a simple selection of right colored spring for the waste gate gets you either 5, 7, or 9 lbs of boost equating to between 500 and nearly 700 rwhp. That’s rear wheel horsepower for those with scorecards, and a clear reason why that Hellcat Challenger was overmatched. In essence, we are talking about close to 800 hp at the flywheel!

Why does it work?

If you recognize that last name, you must be either really old, or really automotive tech savvy.

If you fall into the older category, you probably know the name Granatelli from the famous massive, trench coat-wearing Indianapolis 500 Race Car Team owner, who won more that his share of races with racers bearing names like Parnelli Jones, Graham Hill, and Mario Andretti. But Andy Granatelli may be best known for the STP racers that did not win, his Turbine cars of the late 1960s resetting every record at that legendary race track, and missing the win in 1967 due to a failure of a $6 transmission bearing.

For those in the latter category, you know the name Granatelli for the efforts of Joe (JR to his friends) Granatelli and his advanced automotive emporium in Oxnard. There by the sea, JR cranks out some crazy fast stuff, be it road racing track cars, high performance trucks, super fast street cars, or even King of the Hammers high-speed sand dune attack vehicles. The Sweasey Camaro is just one of his latest brainstorms-turned-tire-frying machines. Goodyear and Michelin should send him royalty checks!

The design for the turbo system is pure genius. While most turbo systems start with an aftermarket exhaust manifold that mounts a turbo or two, Granatelli decided to use GM engineering for this base, retaining the factory exhaust manifolds that deliver the ultimate durability. This ensures excellent exhaust sealing and avoids the cracking often found with header systems.

Aptly named the One G for Two G’s suspension system, Granatelli developed a kit that includes this impressive bracing system tying the frame rails in a highly efficient manner. Best of all, there are no issues with ground clearance, especially with this daily driven Ca-maro. Chris Sweasey insists on maintaining factory ride height to haul around his “valuables.”

Granatelli offers two levels of turbochargers, either journal bearing or ball bearing. The difference: the ball bearing turbo delivers the peak of performance, the journal bearing system saves the buyer $1,000 — it’s that simple. For anyone looking to run hard and long, such as running the Silver State Classic or Texas Mile, check the box for the ball bearings.

The tubing system, mentioned earlier, is connected with a series of high-end V-Band clamps that negate the need for gaskets that can wear in high temp applications. But by positioning the turbo low in the system, protected by the Camaro frame, the turbo is naturally cooled by airflow under the car. That means greatly reduced underhood temp that diminishes engine efficiency and robs potential engine power.

Helping to cool the intake charge and generate the greatest power is the High Flow Bell front-mount intercooler. With 3.5-inch in-lets and a 4-inch diameter discharge pipe, the airflow is massive. For added appeal, black powder coated tanks dress the intercooler itself, while fiberglass-reinforced silicone hose couplers provide solid durability.

While the turbos sit just high enough to gravity feed back to the oil pan, Granatelli opts to include an ultra-high-flow scavenge pump to ensure the turbos are “dry sumped” as soon as the oil does their job cooling the bearings. This pump simply sucks the oil from the common drain tank and pumps it back up to the passenger side valve cover, where it interacts with the proper PCV.

Two G’s for one G

Aiding traction with the Camaro is the Granatelli Motor Sports 1 G Suspension System that delivers the structure needed to help Chris Sweasey “stick the landing.” The system includes an assortment of suspension braces that bolt to the frame in key locations. For Sweasey, having the stock ride height was key to his daily driver purposes behind the Camaro. To maximize handing, dropping the height would be advised.

With all that power, Granatelli Motor Sports includes a recommended brake upgrade. While they use the factory Camaro Brembo calipers (also available through Granatelli), Granatelli modifies an Alcon rotor adding a series of science slots and drill holes, different front and back, to dramatically improve high-speed stopping. Granatelli uses the factory brake pads, which he feels are more than adequate for high performance driving.

In our test drive, the Camaro’s power was plenty evident, coming on like a strong tidal wave of torque. Since the Camaro features a stock automatic transmission and rear end, stabbing and steering is ill-advised. Instead, the best technique is to achieve about 30 mph before kicking in the turbos, to keep the power from tearing up the driveline. And kick in it does. The power band starts quickly — no turbo lag — followed by backside compressing force.

The Granatelli Twin Turbo package offers a complete solution to turbocharging that is perfect for the street or racing. Having conquered such high-speed events as the Silver State Classic, a flat out, 180-mile speed test through the Nevada desert, and many other road racing events, the turbo system design has an impressive “track” record. But its street manners are what set it apart — the perfect street-strip-race combination. Uncle Andy would be proud.