1000hp twin-turbo LSX HQ Holden

Greg South’s sweet HQ sedan hides its twin-turbo LS bones so well you’d never pick it for a 1000hp monster.

Photographers: Ben Hosking

Greg South’s eye-punching HQ Kingswood looks good enough to take trophies at our best indoor shows, and, thanks to a twin-turbo 427-cube LSX, it has enough power to smoke out the straight at Powercruise. But he didn’t build it for either.

1000HP Twin turbo LSX HQ Holden frontWe’ve all got one mate who has the fastest or angriest car in the group, and so it was for Greg. One day, he decided enough was enough: “I thought my mate’s twin-turbo V8 Commodore needed some competition, and I had an HQ sitting in my mum’s field for a few years,” he explains.

1000HP Twin turbo LSX HQ Holden frontAs the proprietor of G Force Automotive in Narellan, NSW, the mechanic and engineer has had some cool toys, including a couple of hot rods, a C10 pick-up and an LJ, but it was practicality that drove Greg’s choice of an HQ. “I’m six-foot-three and just don’t fit in Toranas,” he says. “I wanted the bigger car, and I only like the plain HQ sedan – I don’t like GTS guards, twin-light front-ends, HQ coupes or HJ rear ends, I prefer the lights in the bumper. Another benefit of having an earlier model is that it makes it easier for emissions laws and engineering.”

It wasn’t until he had it blasted that Greg discovered the shell he’d stashed at Mum’s turned out to be too far gone for what he wanted. “All the sills, cowl and inners were gone when we got it back; it was cactus,” he says. “Then Cain from Xtreme Fabworx called and told me he’d found a better shell. I went to inspect it and it was 90 per cent straight, in high-fill and already mini-tubbed. The price was great, so I left the new car with Cain and he started straight away.”

1000HP Twin turbo LSX HQ Holden rearThe Xtreme Fabworx boys then set about cutting, bashing and grinding to Greg’s requirements. “Most of all I wanted no holes or scoops in my bonnet,” he says. “A flat bonnet is a must, but Cain got it done!”

Xtreme modified the bonnet to clear the intake and the inner guards around the turbos, fitted a hidden parachute mount in the boot, and a custom six-point rollcage with removable taxi and side bars. Greg also dove in and made up the custom radiator panel and bonnet latch to work around the radiator and intercooler.

The slick sedan also features tucked wiring, fuel and brake lines, an auto trans cooler and fan under the boot floor, and a modified grille to clear the intercooler.

Rodney Piper then got the job of laying down the 2K clear-over-base top coat to Greg’s exact specifications of “the brightest red you can get”.

1000HP Twin turbo LSX HQ Holden engine bayThe lairy colour matches the mega-power twin-turbo engine under the bonnet, which came about with a little help from Greg’s neighbour.

“I was having a chat to my neighbour Sam, who said he had an engine sitting around he wasn’t using,” he says. That neighbour just happened to be Sam Fenech of Westend Performance, who is rather used to building massive-horsepower engine combos.

The 6.0-litre LSX block has been stuffed with a Callies crank and rods, with Arias pistons pushing the cubes up to 427ci. CNC-ported heads from Mast were used, fitted with heavy-duty pushrods, 1.8-ratio T&D shaft rockers and topped with that awesome Ozmo carbonfibre intake manifold that inhales through a billet 102mm Nick Williams electronic throttle.

Twin Precision 6766 turbochargers have been mounted up in the breeze on custom high-mount mild-steel manifolds, which were HPC-coated for better thermal efficiency. The front-mount intercooler and matching radiator come courtesy of Shaun’s Custom Alloy. Greg chose an Aussie-made Haltech Elite 2500 to control the stout combo, wired up by Justin at Ultimate Wiring with a custom loom to suit, and tuned by Haltech and LS guru Dale Heiler from Castle Hill Exhaust.

1000HP Twin turbo LSX HQ Holden rearA Paul Rogers-built TH400 has been stuck in the trans tunnel, rocking a 3300 TCE converter and passing torque down a custom 3.5-inch tailshaft to a sheet-metal nine-inch diff that copped bracing, a Moser centre, Mark Williams end caps, 3.55 gears and Strange axles.

Rather than sending it to the tip, Greg and his mates used the buggered shell as a dummy to test-fit the drivetrain and suspension components, which Greg went above and beyond on to ensure the HQ handles better than ever. The rear end copped the bulk of the work, with custom adjustable Strange coil-overs on custom mounts, custom adjustable triangulated four-link and a Panhard bar, all by Xtreme Fabworx.

1000HP Twin turbo LSX HQ Holden boot openHaving made a PB of 1008hp on 20psi, the original engine was torn down in December last year after it hurt a bearing. Greg bumped compression from 8.5 to 9.5:1 and stuck in a larger custom-ground hydraulic-roller cam, but he was yet to get the new combo on the Mick’s Motorsport dyno as we went to print.

While it has horsepower for days and a show-winning finish, one of the most impressive aspects of the build is the fact it was done in nine months and just in time for Greg and partner Kristy’s wedding! “The hardest part was the deadline,” Greg admits. “A week from the wedding I pulled the pin as it needed the tune and engineering and I thought it wasn’t going to make it.

“My wife-to-be and I were devastated, but Andrew from Motorsport Connections said we were too close to quit. I turned up to get it tuned and Dale Heiler from Castle Hill Exhaust was there and his first words were: ‘You’re getting married and I’ll get you there, no worries’. Three hours later it made 606hp at 9psi boost with a leak, and I was going to my wedding!”

If he can build a stunning, slick 1000rwhp twin-turbo pro tourer in less than a year, we can’t wait to see what Greg does with his long term ’40 Ford pick-up project!