LSA-powered 1963 Chevrolet Impala

A big car like a '63 Impala needs serious grunt, so it is lucky Robert Chauvet's packs a 580rwhp LSA!

Photographers: Ricky Rigutto

This article on Robert’s Impala was originally published in Street Machine’s LSX Tuner #8, 2018

THE early 1960s was a golden era for fans of full-size, high-performance American tinware. All major manufacturers offered horsepower-rich, big-inch V8s packed into large, stylish two-door coupes and convertibles sitting on wheelbases over 115 inches. They put the frighteners up the hot rodders on the drag strips, and southern good ol’ boys turned them into bona-fide race cars in NASCAR’s Grand National series.

“I’m happy with how the car is coming along, especially where the power and the motor is now,” Robert says. “It sounds awesome and the car is very quick for its size!”

But even the fearsome Impala Super Sport 427s doing battle on the NASCAR super-speedways would have a tough time trying to catch Robert Chauvet’s LSA-powered ’63 Impala. With some minor upgrades, his blown 6.2-litre small-block puts out 580rwhp, which is way more than anything GM had in its production car stables back when JFK was still president!

“I’ve always liked full-size American cars,” says Robert. “I like the cruiser and lowrider cars more than the Australian muscle cars, but this car didn’t quite end up turning out like that!

“I got myself into the position to buy one, so my dad and I started looking around, and then I found this car in Queensland. It had a 454 big-block in it and sounded nice and lumpy. The guy I got the car off had done a lot of the work himself, including lowering the car and fitting bigger wheels, though it still had a Powerglide in it.”

The big B-body Chev rides on King Springs all ’round with Bilstein shocks set up by the gurus at Heasman Steering, who also added Polyair helper airbags to the rear to help tame the tail-happy characteristics the Impala had. “When we went out first time, the back was sliding around,” says Robert. “We had the airbags added inside the springs to help stop that and stiffen it up a bit”

While that sounds like Robert was ready to cruise off into the sunset, the temperamental nature of old-school engines killed his buzz only six months into the ownership of his dream car.

“I used the car for a bit, but the carburettor-fed engine took a while to start up and didn’t run perfectly,” Robert explains. “It was one of those moments where it was midwinter and my dad and I wanted to go for a cruise, but the car was just spluttering and wouldn’t run. I wanted the car to be more reliable so I could just jump in and go for a cruise, and not worry about the engine on trips as much. Then I got carried away.”

Carried away sometimes means buying the polished rocker covers instead of the plain ones, but Robert went a bit further with his plans and wound up doubling his horsepower goals.

“Initially I was just going to get a basic LS1 engine and fit that, but then I found an LSA,” Robert admits, adding that he actually scored himself something of a bargain. “I was on eBay one day and found a VF GTS LSA with about 30,000 kilometres on it. The package included the engine, transmission, wiring and ECU for $15,000, so I bought it.”

Sitting behind those awesome American Legend Thunderbolt wheels are Wilwood four-piston calipers and discs. You’d be hard-pressed to see them given the fat 8in front and 10in rear diameters of the polished hoops

While the stock 580hp LSA would be plenty in an Impala, given the top-spec Z11 factory race cars were only rated at 430hp, Robert wanted more.

“I sent my engine to the guys at Russo Performance because they’re close to my house and they have a great reputation for building and tuning LS engines,” says Robert.

GM’s 6.2-litre supercharged LSA is arguably the cheapest way you’ll get yourself a brand-new, reliable 580hp small-block with service and repair parts available at any auto parts store. With a cam and some more aggressive pulleys they can make impressive amounts of power without breaking the bank or turning them into undriveable pigs.

Robert’s Impala now makes 580hp at the bags thanks to the upgraded cam, double valve springs, 1000cc injectors and a hike in supercharger boost pressure to 11psi, all tuned through the stock GM ECU.

This has been paired with a TH400 – the same trans found behind mid-60s big-block muscle cars – built by Craig’s Automatics in Sydney to handle all the power and torque the LSA can throw at it. It’s paired to a 3000rpm Dominator converter and a built nine-inch diff out back that now spins a Truetrac centre and 31-spline billet axles, so Robert knows his drivetrain will never let him down no matter how froggy he gets on the loud pedal.

He just needed someone to fit the new hardware to his Impala, and he found them around the corner!

“I found Daniel who runs Metal Mavericks and specialises in LS swaps 10 minutes from my house,” Robert says.

Metal Mavericks handled the donk swap by fabricating engine and transmission mounts to sit the LSA and TH400 in the Chevy X-frame. While the Impala is not a tiny car, the Metal Mavericks team still had to take two inches out of the stock engine crossmember to allow the motor to sit flat in the bay and align the TH400 with the stock crossover point in the chassis.

So far the cabin is as GM intended, but Robert has the Impala booked in to be fully re-covered in leather, just days after this photoshoot. The B&M shifter banging gears in the TH400 will remain

“Initially my idea was to fit the VF’s six-speed auto, too, but Daniel explained it wouldn’t fit with the X-frame chassis,” Robert says.

Having also fabricated a full twin three-inch exhaust, the boot floor was modified to allow the Hooker mufflers to sit neatly under the car and point the tailpipes out the rear beaver panel. While they were down the back, the Metal Mavericks team also fitted the Aeromotive fuel cell and 1200hp pump set-up, running half-inch braided line to take the 98RON PULP up to the smoothed engine bay, while the gargantuan Impala boot now plays host to an electric-hydraulic power steering pump out of a Holden Astra.

“When the car was first built, Daniel took me for a drive and it’s a solid car,” says Robert. “I don’t know a huge amount about cars so I trusted him to help me out and he really did. I took people’s opinions and did some research on the internet because I thought that if I’m going to do it, I wanted to do it right, and so I’ll do it right the first time.”

If this killer ride isn’t right, then we don’t mind being wrong!


Anniversary Gold

Brand: GM Gen IV LSA
Capacity: 6.2-litre
Supercharger: Stock TVS1900
Cam: Russo Performance custom-grind
Pushrods: Trend
Fuel system: Injector Dynamics 1000cc injectors, Aeromotive 1200hp pump
Oil system: Custom sump
Cooling: Custom aluminium radiator, thermo fan
Exhaust: Custom 3in system, Hooker mufflers

Gearbox: GM TH400 three-speed auto
Converter: Dominator 3000rpm
Diff: Ford 9in, Truetrac centre, 31-spline billet axles

Front: King springs, Bilstein shocks
Rear: King springs, Polyair helper airbags, Bilstein shocks
Chassis: Stock
Brakes: Wilwood four-piston calipers and discs (f & r)

Rims: American Legend Thunderbolt; 20×8 (f), 20×10 (r)
Rubber: Pirelli (f & r)