Hennessey's 1000hp Commodore

North America’s Australian-built Chevrolet SS, based on the Holden Commodore SS, has been given a massive 1000hp (745kW) tune-up thanks to American high-performance outfit Hennessey.

Needless to say, the Hennessey HPE1000 Twin Turbo SS Upgrade kit transforms the V8-powered four-door from sports sedan to ballistic missile.

Most famous for its record-breaking, Bugatti-beating Venom GT supercar, Hennessey has worked its magic on the humble Holden Commodore, giving it a steroidal power boost thanks to an engine transplant and a pair of massive turbos.

The regular Chevrolet SS is most closely related to the Commodore SS V Redline Fitted with similar suspension and Brembo brakes, the US model gets more power than the Aussie version's 270kW/530Nm 6.0-litre V8, thanks to its larger HSV-style 6.2-litre V8 worth 310kW/563Nm.

Nevertheless, Hennessey has decided there's a suitable market for an ultra-powerful version of the Chevy  SS, which forms the basis of Chevrolet’s NASCAR campaign, and has dropped a 7.0-litre (427ci) V8 powerplant dubbed LSX into the engine bay.

But the fun doesn't stop there, as it has developed a twin-turbocharged and intercooled kit that hikes power to an earth-shaking 745kW, or 1000 horsepower.

In order to reach 1000hp, Hennessey has had to make several changes to the V8 powertrain, including a full blueprint and engine balance job, new intake manifold, custom crankshaft, stainless steel exhaust system, recalibrated ECU, an air-to-air intercooler, new pistons and con-rods, beefed-up fuel-injectors and more.

A pair of twin ball-bearing turbos are matched by dual wastegates and managed by an electronic boost controller, and a high-flow K&N air filter is also added.

Although the company has not listed torque output, it's likely to eclipse 1200Nm, based on the fact the engine pumps out 1000hp/745kW at 6300rpm.

Hennessey is not the first US company to tune the Commodore-based Chevy SS, with Callaway offering its own less radical take on the large rear-drive sedan.

Hennessey offers a one-year, 12,000-mile limited warranty on the upgrade, which also requires transmission upgrades, including a dual-friction clutch for the six-speed manual and a performance build and torque converter upgrade for the six-speed auto.

The HPE1000 kit sits at the top end of the scale, Hennessey also offering HPE550, HPE600, HPE650 and HPE800 kits, some of which use superchargers. Suspension and brake upgrades are also available.

The most powerful aftermarket tuned Holden Commodore tested by motoring.com.au thus far is the $92,000 Walkinshaw W497, which belts out 497kW/955Nm via a supercharger kit.

We clocked the Walkinshaw's 0-100km/h sprint at 4.5 seconds (in damp conditions), so a vehicle with an extra 250kW such as the Hennessey would go even faster, the only limitation being rear-wheel traction.

Note: Image of engine bay is of HPE800 model which uses a supercharger, not twin turbochargers.