Of all the myriad body styles the HQ Holden was offered in, the humble wagon tends to live in the shadow of its siblings among street machiners. Joe Murphy’s 850rwhp, slammed 1973 Belmont wagon shows why we should be paying them more attention.

First published in the March 2025 issue of Street Machine

“I wanted a single-front-light HQ in either a ute or a wagon,” says the West Aussie. “I found this one, so we fixed it up and I cruised it for around seven years with the old 173 and three-speed.”

Slammed on AccuAir airbags, it was a damn cool cruiser, but Joe decided he wanted more. “I’ve known Jeff Johnson since I was young, and I’d watched him build tough stuff and LS engines for years,” he says. “I was inspired by that, and originally wanted a turbo LS with 1000hp.”

With that goal in mind, a revamp began. Joe’s a diesel mechanic, so he did the bulk of the car’s assembly himself, with Jeff guiding him through all the dos and don’ts. “Jeff was mega; he built the engine for me, tuned the car and walked me through setting up the driveline right,” he says.

The Mexican Bowtie in the engine bay is an LS1, still measuring up at 5.7 litres and retaining the standard crank. Aftermarket additions include Lunati rods and forged Mahle flat-top pistons, along with a Crow Cams bumpstick ground to boost-appropriate specs. The heads and intake remain stock, taking up to 22psi from a Proboost SXE-480 turbo. “We capped it at 22psi. I wanted more, but that’s where Jeff said it was happy,” says Joe.

Behind the mill is a Turbo 400, and Joe has MacGyver-ed a genius way of controlling it via the factory column shifter. “We mounted the ratchet shifter on the side of the trans tunnel under the dash, and we spent a few nights working out rods so the factory column shifter operates the aftermarket ratchet one on the tunnel,” says Joe. “It works really well and keeps the interior looking standard, which is what I wanted.”

Punching all that power through to the ground is a Borgy diff from a VN Commodore, and in street trim, Joe runs custom BCI 18×7 wheels that take the original hubcaps. “Since the photoshoot, we’ve also built some custom-width 15s to take the hubcaps as well, but either way, it’s about the sleeper look,” he says.

The suspension is still the AccuAir airbags the car had before the driveline conversion; they were a bolt-in replacement to help the big ’Q lay rail. “It gets close to rubbing, but I got lucky and it all just fits,” says Joe. “It is pretty wild to drive in anger on the ’bags, but it’s still heaps of fun.”

Since the car’s completion just over 12 months ago, Joe has hit up Motorvation twice, as well as Gazzanats in Darwin, where we shot these photos and he won the roll racing competition. “No proper drag racing yet, but I’ve done some more roll racing in Perth,” Joe says. “I love loading the car up with mates in the cruise sessions at events and blazing tyres. The wagon loves it!”

The party car still sees its fair share of street duties, too, with Joe often loading it up with the kids for a Sunday cruise. “It has two boost settings, so we can roll it down to around 500rwhp when I want,” he says. “I’ve already done 6000km since it was rebuilt, so we use it quite a bit.”

As for future plans, Joe isn’t ready to let go of his ambitions of a 1000hp sleeper just yet. “I have a 6.0-litre engine we’ll build in the background that’ll hopefully see 1000hp,” he says. “I built the rest of the car for that, so it’d be mad to have a sleeper with 1000hp – that’s every kid’s dream!”

JOSEPH MURPHY
1973 HOLDEN HQ BELMONT WAGON

THANKS
Jeff Johnson for help with driveline set-up; Matthew Wilson at MKW Engineering for all the fab work; Mitch Shean and Ryan Lazarakis for the panel and paint; Richard’s Trimming & Upholstery Services; Ignite Auto Electrics for wiring the car front to back; Luke Milligan; my wife Hannah Sharpe.

Got a car that looks mild but goes wild? Email pics, car details and contact details to [email protected].