Budget turbo LS1-powered HQ Kingswood at Drag Challenge 2018

Justin Mitchell has ditched the much-abused aspirated LS1 in his HQ Kingswood for a turbo iron 5.3 and is ready to send it

Photographers: Chris Thorogood, Michelle Porobic

DRAG Challenge veteran Justin Mitchell has ditched the aspirated 5.7-litre LS1 in his ‘50 Shades of Brown’ HQ Kingswood in the pursuit of getting the full-weight sedan down into the mid-10s.

Holden KingswoodJustin moved into the Haltech Radial Blown class for Drag Challenge 2018 to help him keep to the schedule he wants to maintain. “We want to get in early, do our runs and get out while the air is good, so running in Radial Blown will help that,” he says.

The new combo is an iron truck 5.3-litre LS motor with a BorgWarner S475 snail that can run from 14psi up to 18psi, with pump gas in the tank instead of an ethanol blend.

Holden Kingswood“After torching a couple of pistons, we first found the fuel system wasn’t up to the task, and then we discovered the intake air temps were through the roof,” Justin says. “I’ve added a water-methanol spray to the intake pipe ahead of the throttlebody and those intake temperatures are perfect now. The car hasn’t been dyno-tuned; we did it all on the street.”

Backed by a 3500rpm converter and TH400 three-speed trans, with the spooled HiLux diff and 3.5 gears in the rear, Justin drove the HQ to the event from Sydney, with mates Kris Reberger and John Grech along for the 900km ride.

Holden Kingswood engine bay“We just cruised along and it ran great on the road. This car goes everywhere!” says Justin. “This car has done it all, including burnout competitions and even done a few trips through the Summernats burnout pad, but it keeps on going.

“I’m hoping to knock out a 10.6 at some point over the week, depending on what the tracks are like and if we can get a clean pass.”

After plenty of on-road tweaks, Justin laid down an 11.75@127mph on Day Two at Swan Hill, then a 7.54@103mph on the eighth-mile at Mildura on Day Three.


Class: Haltech Radial Blown

Engine: 5.3L LS
Turbo: BorgWarner S475
Transmission: TH400
Converter: 3500rpm
Diff: HiLux, 3.5:1 gears
Power: N/A
Previous PB: 11.1@129mph