80s pro street-inspired blown big-block HK Monaro GTS

Freddy Finnegan’s genuine HK GTS Monaro is a blown big-block salute to the golden era of 80s Aussie pro street

Photographers: Shawn McCann

Memories of the tough street cars of his youth inspired Freddy Finnegan to build his ideal muscle car. “I’ve tried to maintain as much originality as I can, but I always wanted a blown, big-block streeter,” says Freddy of his HK Monaro. “I also love the golden era of 80s south-east Melbourne street machining, which is the theme I built this car around.”

First published in the November 2023 issue of Street Machine

The HK in question is a factory 307 GTS car, but it came with a tough SBC stroker when Freddy took ownership. However, that mill didn’t stay there long.

“I knew the loose history of the engine and had my doubts about it, so I had Danko Knezevic from Adicted Performance pull it,” Freddy explains. “What he found wasn’t good, so we ended up building the 502-cube big-block that I’d bought for another car.”

When Danko opened up that 502, it turned out Freddy had actually scored himself a 555ci stroker. “We were surprised with that!” he laughs. “But it’d had a fire under the blower, so I still had him go through it thoroughly.”

The big-block sports an Eagle billet 4.250 crank, Eagle H-beam rods and JE pistons. The camshaft is an Adicted custom-grind solid-roller, sealed in with DRP heads and a Weiand manifold. Topping the mill is a TBS 8/71 blower, and the whole lot is managed by a Haltech Elite 2500 ECU. “I’ve had old carbies hanging out the bonnet in the past with other cars, but I wanted to keep a lower profile on the blower, so the injection helps with that,” Freddy explains. “Plus, it’s just so much more user-friendly.”

On the Adicted Performance engine dyno, the beastly Bowtie made a comfortable 1021hp and 963ft-lb on 8.5psi of boost and E85.

Naturally, Freddy went right through the rest of the car as well. “It’s got an all-new gearbox, a custom full-fab rear end, and we rebuilt the front end with the brake upgrade and so on,” he says.

That new transmission is a Shotgun Performance Turbo 400 with a converter to suit, while the nine-inch rear houses 35-spline axles and 3.5:1 gears. “With that ratio, it’ll light ’em up really easily if you’re not putting around, and it’ll zap ’em pretty quick off the line if you stab it,” Freddy laughs.

The Monaro has been together in its current form for just shy of 12 months, with Danko’s family-operated Adicted Performance taking care of the bulk of the build. “I’m an expert at building bridges, not cars, so I leave the stuff like this to the real experts,” says Freddy. “You pay these blokes once and they do it right, so I can’t thank Danko and his young boys enough.”

The HK has been known to burl around the south-east ’burbs of Melbourne at least once a month in the warmer weather, and Freddy enjoys every moment in the HK with his son Wrinkles. “He’s 15, and he almost loves it more than me!” he says. “We took it to the Father’s Day show in St Kilda a few months back, and every time I get in the garage and start it or do anything with it, he’s there.”

As you can imagine, the Monaro makes a big impression when the boys do hit the streets in it. “It loves to hunt at idle, so sometimes it’ll try and push through the brakes at a set of lights,” says Freddy. “People are always stopping me and doubling back to look at it, and I love to share the car with people. So if you’re a nice person, I’m happy to let you sit in it, give it a rev and so on – it’s all part of sharing the passion.”

And Freddy has more plans in store for the HK. “The paint was done 20 years ago, and while I want it to stay white, it can be a whole lot better,” he says. “So come autumn next year, I’m going to get Trevor Davis to tear it down, get all the gaps right, sort a nice white for it and get it perfect.”

Given that Trevor is Peter Fitzpatrick’s panel and paint man of choice, we have no doubt it will look flash!

There’ll be plenty going on inside, too. “I’ve already got a full red interior in what we call the ‘Monaro room’ ready to go, which will tie in the car nicely,” Freddy says. “I want to keep the colours simple, and the red will match the butterfly valves on the blower, and the GTS badges. It’s all in the details for me!”


Brand:555ci big-block Chev
ECU:Haltech 2500 Elite
Blower:TBS 8/71
Heads:DRP 340cc
Camshaft:Adicted solid-roller
Conrods:Eagle H-beam
Crank:Eagle billet 4.250
Oil pump:Melling
Fuel system:Walbro 520 pumps
Cooling:Three-core radiator
Gearbox:Shotgun Performance TH400
Converter:Shotgun Performance 4000rpm
Diff:9in, 35-spline axles, 3.5:1 gears
Front:Pedders shocks and springs
Rear:Calvert leaf springs and shocks
Brakes:HQ discs (f), Wilwood discs (r)
Master cylinder:Wilwood
Rims:Center Line; 15×4.5 (f), 15×10 (r)
Rubber:Mickey Thompson; 26×6.00R15 (f), 295/50R15 (r)

Danko, Zac and Sam at Adicted Performance; Jamie at Switched On Electrical; Kenny Perry at Load ’Em Up Towing; Trevor Davis Auto Refinishers in Dandenong; my son Wrinkles.