598-cube big-block Holden HG Monaro GTS

How do you improve on an HG GTS Monaro? Throw in a 900hp big-block and wrap the whole thing in the blackest of cloaks

Photographers: Jordan Leist

FOR plenty of people, owning a Monaro is a lifelong goal, something they’ve dreamed of since they were kids. Perth’s Brad Durtanovich, on the other hand, was always more of a Torana guy: “My first car at 17 years old was a genuine GTR XU-1, and then it went bad from there,” he laughs. “I went through basically every form of Torana, and the only thing I wasn’t that keen on in the early days was Monaros!” The Torana affliction culminated in a four-door A9X that Brad restored; it was awarded Best Four Door at the A9X Nationals in 2003.

First published in the July 2021 issue of Street Machine

But don’t worry, Brad didn’t turn into some rivet-counting restorer after that. In fact, he’s built a couple of seriously tough cars since then, including an EK Holden and a ’57 Chev, both featuring blown small-blocks.

The HG GTS Monaro you’re looking at now entered the picture around 10 years ago. “I bought it from Karratha, sort of on a whim,” Brad says. “A few mates had Monaros at the time and one of my mate’s sons showed me the ad. It was already mini-tubbed and had a small-block in it. I believe it was at Motorvation sometime in the 90s, and it already had 15x12s on it back then.”

When Brad purchased the car, it was fitted with a small-block, but it wasn’t long before he had the late Jeff Clarke build a mild big-block for it. Brad drove it around like that for two or three years before pulling it off the road for a full rebuild. “It was starting to get a bit ragged around the edges and a bit of rust was coming out here and there,” he explains.

To whip it into shape, Brad entrusted the car to Neil Moneypenny at XclusiveFX. Neil had the car for around seven months, during which time the rear quarters were repaired, and new guards and bonnet, supplied by Todd at Rare Parts, were fitted. It also scored a colour change: “There wasn’t really any intention to go black; it was more about making it a respray in a decent colour, as it was white when I got it,” Brad says. “Neil’s probably the most reliable guy that I’ve ever come across in terms of knocking out a paintjob in a reasonable amount of time for a reasonable amount of money.” A rare statement from a feature car owner, that’s for sure!

What sets this car apart from all the other killer black Monaros out there is what’s in the engine bay. Nestled between the gloss black firewall and inner guards is a beautifully detailed 598ci big-block Chev. While it’s not polished, chromed and smoothed to show car standards, there isn’t a single thing out of place in the engine bay, and the mix of satin and polished aluminium ties in really well with the black surroundings. The centrepiece is that awesome Edelbrock tunnel ram that was polished to perfection by Wheelgleam, to which Brad added a couple of Quick Fuel Technologies 1050 Dominator E85 carbs. All those cubes needed a healthy diet of corn juice, which is stored in a massive 100-litre custom tank that was beautifully crafted by Nelg’s Ali Mods. An Aeromotive fuel system makes sure the fuel gets to where it needs to go.

The mill was screwed together by legendary West Aussie engine builder Derek Paulik, who started out with a Dart Big M block punched out to 4.600 inches and then filled it with a Scat 4.500 stroker crank, Scat H-beam rods and Diamond pistons. A Crane solid-roller cam gets the massive 2.30 and 1.88 valves moving in the AFR Magnum 357 heads, which dump out the waste and sweet sounds through a set of two-inch headers from Castle Headers. Mufflers R Us then finished off the exhaust with a set of twin 3.5-inch pipes that run all the way to the back of the car.

On C&R Motorsport Developments’ engine dyno, the motor punched out over 900hp, which resulted in 748hp at the tyres when the car went to George Separovich at Blown Motorsports for a final tune-up – I would call that ample.

The rest of the drivetrain is just as bulletproof, and features a Reid-case Powerglide, a Dominator converter with 4500rpm stall, a driveshaft from Final Drive and a nine-inch filled with a 35-spline Strange centre, Truetrac and 3.5:1 gears.

Brad’s obviously got the show and the go parts covered, but how about the whoa? Yep, that’s all good too, thanks to a Wilwood braking system that includes drilled and slotted rotors on all four corners, and a Wilwood master cylinder. Even the handling has been improved with a Southern Chassis Works front end, rack-and-pinion steering and Viking coil-overs front and rear.

With the major parts of the build handled, it was time to send the HG off to Dicker’s Speed Shoppe to button everything up. “Dicker’s did the fuel system, brakes, wheels, full rewire, interior and under-car love,” Brad says. By “under-car love”, he means all of the brake and fuel lines as well as the clips and brackets to make everything neat as a pin.

Rare Parts was also tasked with sourcing and supplying the beautiful Sandalwood interior trim, which was installed by Nick from ANF Automotive Interiors while the car was at Dicker’s.

The Monaro was finished just in time to be unveiled at Motorvation 35 and scored Judges’ Choice, a Top 10 spot and a Superstars invitation. If I was giving out trophies, it would have got one from me as well! After all, what’s not to love? Perfect paint, a pristine interior and enough horsepower to keep a smile on your face all day long.


JUST as we were finishing our conversation about the Monaro, Brad mentioned he’d just purchased the late Adrian Tally’s LC Torana. The brown more-door with a white roof might not sound like something a bloke with a 900hp Monaro might want, but the little Torry holds a special place in the hearts of many West Aussie street machiners, as it was a legendary performer at Motorvation and other burnout competitions throughout the 90s, and was a regular at Ravenswood Raceway as well, running 11.006@125mph with a nitrous-fed junker 308 back in 1996!


Type:598ci BBC
Inlet: Edelbrock tunnel ram
Carb: Twin QFT 1050cfm E85
Heads: AFR Magnum 357
Valves:2.30in (in), 1.88in (ex)
Cam: Crane solid-roller
Pistons:Diamond forged
Crank:Scat steel
Conrods: Scat H-beam
Radiator: Brown’s aluminium
Exhaust:Twin 3.5in
Gearbox: Reid-case Powerglide
Converter: Dominator
Diff: 9in, 3.5:1 gears, 35-spline Strange centre
Front: Southern Chassis Works IFS, Viking coil-overs
Rear: Viking coil-overs
Steering: Rack-and-pinion
Brakes: Wilwood discs (f & r)
Rims: Weld AlumaStar 2.0; 15×4 (f), 15×10 (r)
Rubber: Mickey Thompson ET Front 26.0×4.5-15 (f), Mickey Thompson ET Street S/S 295/55R15 (r)

Neil Moneypenny from XclusiveFX – paint genius. Thanks for all the extra hours you put in to get it to Motorvation; Dicker’s Speed Shoppe for final assembly and amazing attention to detail; Nelg’s Ali Mods for the killer fuel tank; Shane Kirkman for the full rewire at Dicker’s; Derek Paulik – master engine builder; George Separovich at Blown Motorsports for sorting out tuning gremlins