Home-brewed crusty L98-powered HQ sleeper

Brian Petrass had never built a car before, but his patina-cloaked, 409hp HQ is all killer, no filler

Photographers: Caprice Photography

Having spent his life running a farm in Horsham, Victoria, Brian Petrass recently found himself with time on his side and an itch to finally build a car for himself. However, while he chose Holden’s most popular 70s model for his project, he’s no one-eyed fanboy. “I had an HQ as a young bloke, but I couldn’t wait to get rid of it, because they drive like a bucket of shit,” he laughs.

First published in the January 2024 issue of Street Machine

The HQ you see here certainly doesn’t, though – not once Brian was finished with it, anyway. “I looked for one for ages, and this one was in a shed 10km from where I live,” he explains. “It sat outside for several years, and I was going to paint it, but my mate Jeff Umbers introduced me to patina, which meant instead of spending money on paint, I had money for mechanical stuff.”

Two years’ worth of work has left Brian with a killer streeter, and one that hides almost all of its smarts. “I wanted modern running gear in an old car,” Brian says. “I hadn’t built a car before, but the HQ was all done at home in my shed. I went and bought a Commodore ute from the auctions to get the [6.0-litre L98] engine; the only reason I bought it was because it had an aftermarket exhaust. I didn’t know it had a big cam until I got it home and started it!”

Many people would have been tempted to show off all the hard work, but Brian likes his cars understated. “I like wolves in sheep’s clothing,” he says. “I wanted something to look like a piece of crap but it is actually far from it, so everything you can’t see is painted nicely.”

There are plenty of quality parts under the HQ’s farm-fresh skin. A full Castlemaine Rod Shop front end, including tube control arms, steering rack, Viking coil-over struts and four-pot disc brakes, offers a significant upgrade, while the Geelong Diffs-built nine-inch puts the power down better than any banjo ever could.

“The Rod Shop front end means it actually stops and steers nice, and is a really good thing to drive,” Brian says. “Everyone does autos, but I love my manuals, so I fitted the six-speed, but it did involve a lot of cutting of the floor to make it fit. Still, it’s awesome, as my nine-inch diff has 4.11 gears, but I’m still doing 1800rpm on the highway!

My mate Jeff, who was instrumental in helping me with the build, came with me for a drive, and we couldn’t work out why it was going so good. Then we worked out [the HQ] was 500kg lighter than the Commodore [the engine came out of].”

Brian is enjoying taking his HQ out and using it, especially if it involves pulling the wool over the eyes of some enthusiasts who aren’t expecting such a well-specced build upon first glance. “I went to the SA All Holden Day in Glenelg and kept my hat over the gear shifter in the middle, and I kept the bonnet shut,” he laughs. “The odd person clues in, and I know when they look underneath, then you’ve got them, so I’ll sneak over, pop the bonnet and move the hat and people start talking about that HQ they’ve seen. It would be hilarious to record people’s reactions when they see the engine bay.”

It’s a seriously impressive job to knock out such a well-sorted machine for your first car build, but Brian is a practical fella.

“I built the entire car in my shed at home with Jeff and my kids Brendan and Brooke,” says Brian. “All I’ve done is change the oil, plugs and leads, and that’s about it. It drives so good!”


Engine:GM 6.0L L98
Cam:Aftermarket, unknown specs
Transmission:Tremec T6060
Diff:9in, 31-spline axles, 4.11:1 gears

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