Tuff Mounts LS1-swapped Sigma ready to tackle Drag Challenge

Tuff Mounts boss-man Jason Waye hopes to smile his way through Drag Challenge in this tidy 235-class LS-powered Sigma

Mitsubishi Sigma 4 Jpg
Gallery23

PLENTY OF US have good – or maybe not so good! – little-kid memories of the back seat of a Chrysler Sigma, one of Australia’s most popular family cars of the 1980s. But even with the ground-breaking Sigma Turbo in the model range, it’s not often you read ‘Sigma’ and ‘performance’ in the one sentence.

LS-powsered Mitsubishi Sigma
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Jason’s is not the first Sigma to front up at Drag Challenge – Sydney’s Domenic Pelle brought an turbo LS-powered Sigma to DC last year and is bringing it back this year – but with the build of Jason’s Sigma being a development program for his Muscle Garage/Tuff Mounts bolt-in engine swap kit, it’s certainly not going to be the last V8 one we see, either!

But that’s not to say you can’t bulk-up a Sigma… as Radelaidian Jason Waye hopes to prove at this year’s Street Machine Drag Challenge. He’s shoved one of GM/Holdens formidable all-alloy LS1 V8s into one!

“It was dying to be done!” chuckles Jason, the boss at Muscle Garage and Tuff Mounts.

Mitsubishi Sigma boot
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Why a Sigma? “I saw a Sigma when I attended Drag Challenge Weekend in Queensland and I thought – what a great idea! They have a big engine bay!” There was another reason, too – Jason wasn’t confident he’d get his Barra-powered 1980s Ford Mustang completed in time.   

The due-by-DC build began in late June. A few mates around the country kept their eyes open for a suitable project car but Jason found his Sigma – already swapped with a carby Holden V8 and Trimatic – in Victoria.

LS-powsered Mitsubishi Sigma
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This Sigma was re-painted when the carby Holden V8 was dropped in. That was around 20 years ago so it’s not perfect – but it’s certainly nothing to be ashamed of. For DC, Jason has fitted a reverse cowl bonnet. Inside it has its grandma-comfy quilted-and-buttoned top-line trim but Jason will be driving DC with a Kirkey drag-spec alloy seat in the car so he can fit the cabin with a helmet on!

To repower it, Jason bought an ex-WK (VY) Statesman engine, trans and ECU/loom. Showing 140-ish thousand kilometres, it was disassembled for a look inside. The heads were sludged with carbon so were cleaned and serviced with new springs and stem seals. The piston/rotating assembly – and compression – wasn’t touched, but a VCM 710 cam and oil pump kit was installed before Jason made it all fit the Sigma engine bay. With the modest mods it makes 260kW at the wheels.

LS-powsered Mitsubishi Sigma
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Big-engine, smaller-body sleepers have been a part of street machine society for decades. But not all sleepers make sense. Just because you can, doesn’t mean you should! The Sigma makes sense: the engine bay has plenty of clearance and the stout body can be torqued up with big power without popping the door latches. The beefy body – and its weight – plus parts interchangeability with other Aussie cars (such as brakes) make it a relatively simple engineering exercise and a great home for a V8.

The 4L60E four-speed overdrive autos aren’t known for strength under pressure, so it was rebuilt with upgraded clutches, bearings and valve body.

LS-powsered Mitsubishi Sigma
23

“Done properly, these are a reasonable trans,” Jason reckons. “I wanted one because it needs to be a road car for Drag Challenge – not just for down the strip. If you pump up the pressures and change the shift points in the tune, it doesn’t work for long; you need to do it properly internally.” The JRM Transmissions-built ’box runs an AK 3600rpm convertor and fits the Sigma trans tunnel with little more than a few hammer hits for clearance. The rear axle is a narrowed ex-Commodore BorgWarner that was already there.

“It already had a lot of the stuff we needed,” says Jason of his bargain buy. “Buying it like that [with a V8 swap] didn’t make the engine transplant any easier but it saved us time and some money as it already had a [tougher transplanted] diff in it and it had bigger V8-spec VR Commodore brakes all around.”

LS-powsered Mitsubishi Sigma interior
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Now the car is completed and registered, Jason knows from test launches that it has a tricky torque-bias type centre in it, too – but he’s not sure what brand!

“It was a pretty quick build, really, and I can’t wait to hit the road in it!”

Jason Waye
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Jason will be contesting the Tuff Mounts 235 Aspirated class at Drag Challenge.

JASON WAYE
1981 MITSUBISHI GH SIGMA

Engine: GM/Holden LS1 5.7-litre alloy V8
Cam: VCM
ECU: Holden LSI with modified loom
Trans: GM/Holden 4L60E four-speed auto
Convertor: AK 3600rpm
Diff: Holden/BTR with 4.1 cogs and torque-sensing diff

 

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