WhichCar
Powered by
  • WheelsWheels
  • MOTORMOTOR
  • 4X4 Australia4X4 Australia
  • Street MachineStreet Machine
  • Trade Unique CarsTrade Unique Cars

Turbo SBC-powered Holden LH Torana sedan

By Iain Kelly | Photos: Michelle Porobic & Chris Thorogood, 26 Dec 2018 Drag Challenge

Turbo SBC-powered Holden LH Torana sedan

Dave Johnston was aiming for nines on debut at Drag Challenge with his turbo blow-through small-block Torana

EVEN builds taking more than a decade can end up as a mad thrash to get ready for Drag Challenge, and Dave Johnston found that out this year when he decided to debut his LH Torana sedan in the Haltech Radial Blown class. Dave’s crisp white four-door rocks a turbocharged small-block Chev, running a blow-through carburettor instead of EFI.

Holden Torana“The goal for the car has always been to drive to the track, run a nine, and drive home,” said Dave. “It’s taken 15 years to build the car, so that might not seem so impressive today when there are seven-second street cars around, but I built pretty much the whole car in my shed.”

Under the slick, straight white tinter paintjob is a 400ci small-block Chev running forged internals and a solid-roller cam, topped by AFR 210 alloy heads. Boost is created by a BorgWarner S475 turbocharger and rammed with force into a CSU 750cfm blow-through carb, where it mixes with a strict diet of 98RON pump juice.

Holden Torana“I will start on 11psi and eventually work up to 20psi once I’m used to the car, as it is all a learning process,” said Dave at the beginning of Drag Challenge. “The bottom end should hold 2000hp safely, and if I max the turbo out it should be making 1500hp pretty easily.”

Backed up by a Powerglide and nine-inch, the car has taken up space in Dave’s shed for 15 years, with the build lasting 11 of them. Impressively, he’s done the lion’s share of the work himself. “I built the motor and did all the body prep in my shed, while a mate painted the car for me,” he said.

Holden ToranaBut even with such a long build time, it still came down to the wire to get the car to DC. “We got to the dyno very late on Thursday night, then had ignition issues,” Dave said. “Because it is a blow-through turbo set-up, we don’t have access to datalogs to help tune the car, so we used trial-and-error to get it sorted. Unfortunately we ran out of time on the dyno and only made 336rwhp on 3psi.”

Dave got the issues fixed and had a good first day at the track, with a 9.74@113mph over the 1000ft at Calder, before having to pull the front of the car apart on the side of the road to fix a horror oil leak from the front main seal. After several hours, the boys got it fixed and turned up ready to party in Swan Hill at around 10:30pm.

Holden ToranaUnfortunately the racing gods decreed that Day Two would be Dave’s last in his first crack at DC, with the converter completely disintegrating on his first pass of the day. Despite spending several hours on the phone in an attempt to source replacement gear, Dave decided to call it a week and not risk his beloved Torana any further.

“The shop that took it apart said it’s the worst they’ve ever seen; they can’t even explain why it broke because there’s nothing left to analyse,” he said.

Holden ToranaDave didn’t let it dampen his spirits though, and was proud that his 100 per cent shed-built Torana made an appearance at DC. He can’t wait to give it another crack next year. “We’ll definitely be back next year; we’ve all vowed to come back again and even my wife has said I have to go back and try again.

“I’ve already bought two mufflers to quieten it down for next year because it was painfully loud on the road, and we’ve figured out what we need to do differently to survive the week.”

DAVE JOHNSTON
1975 HOLDEN TORANA SL

Class: Haltech Radial Blown

SPECS
Engine: 400ci small-block Chev
Turbo: BorgWarner S475
Transmission: TH400
Converter: TCE 4300rpm
Diff: 9in, 3.25:1 gears
Power: 338rwhp (3psi)
Previous PB: N/A
Best Drag Challenge 2018 Pass: 9.74@113mph