DOMINIC PELLE
MANY street machiners will have a begrudging respect for the Sigma, Chrysler Australia’s bigger-than-most four-cylinder family car, even though it more-or-less killed the Valiant. Designed by Mitsubishi in Japan but adopted, extensively re-engineered and manufactured in Australia, the Sigma was to Chrysler Australia what Commodore was to Holden at the dawn of the 1980s: a smaller, lighter, fuel-efficient family car.
But Dominic Pelle didn’t care about all that, because for Drag Challenge 2018, he stuffed a freakin’ enormous LS2 V8 into one, plumbed it with a turbo, had it all legit engineered for street rego, and hoped to throw down a string of eights!
Dom isn’t new to the DC game; he’s participated in the past couple of events with a turbo Ls-powered HK Kingswood that he drove down from Sydney. The Sigma, too, is a driver, fully engineered and legal with its new LS.
Fitting the 6.0-litre, all-alloy, ex-commodore V8 to the Sigma involved a modified front crossmember and GM Performance Parts switcheroo sump intended to fit an LS into a Fox-body Ford Mustang. The turbo – a Borgwarner capable of spooling enough air for 1000hp – lives not in the engine bay but under the boot floor, installed on a laser-cut flange plate and its own crossmember, and fed from two 2.5-inch primaries that meet under where the back seat used to be. Dom and his mates who helped – Simon Render and fellow DC participant Nathan Clarke – are all ‘in the back shed’ blokes, so the exhaust was fabbed from bits of scrap pipe.
The fuel system – PULP and E85 – is based on an Aeroflow dual-chamber tank in the boot, sealed from the cabin and drained by two Walbro pumps. It’s intercooled too: water-toair for the street, and with a bit of extra cooling provided by an icebox in the boot. With the turbo out back, the easiest path for the intake plumbing was through the cabin. No back seat; it’s engineered and registered as a two-seater.
The trans is a Shift Right-built, Reid-cased Powerglide that required a few tunnel modifications to fit under the Sigma’s floor. The diff is suspended on coil-overs; it’s a tough Ford nine-inch with Mark Williams axles and an alloy carrier. The rear tyres are Mickey Thompson 275/60s on 15x8in wheels.
Dom has also put plenty of effort into making the old classic look good, fitting a stack of newold-stock components such as light lenses and bumpers. The Starion Turbo steering wheel is a respectful nod to the car’s JDM heritage, too.
Like a lot of Drag Challenge participants, Dom had a few dramas in the weeks leading up to the event, particularly with the torque converter (it managed to rip free of its flexplate while the car was on the dyno!) but he arrived at Calder rarin’ to go after towing the just 4km-old car from Sydney. “I wish I’d driven it down, as it turned out it was perfect on-road,” he said.
Towing a trailer for Drag Challenge, the mighty Sigma sipped just 14L/100km on Drag Challenge’s cruising sections. But on-track, Dom had some ‘new-build blues’.
“I could only get about 1.5lb boost on the startline,” he explained. “Put simply, the converter was too tight, so I couldn’t get it above 1800rpm, so with the big turbo it couldn’t build boost against the transbrake.” The result was a lowly 2.4-second 60-foot – Toyota Corolla territory!
Another issue: The intercooling wasn’t as effective as it could have been, which meant higher-than-ideal intake temps caused the management system to safeguard the engine by retarding the timing.
“So, it had a soft start and a soft top end,” Dom laughed. “But it was bullshit fast in the middle! Phenomenal – it will be much stronger than the HK!”
Dom’s best quarter-mile ET was an 11.83@130mph – well short of the car’s potential – but the times will tumble as he chips away at the teething problems. We’ll be watching with interest!