Tubbed and blown 2005 Holden VZ Monaro

Tubbed, blown and legal - Jim Polentas took a wilder path when he bought his second Holden Monaro

Photographers: Shawn McCann

This article on Jim’s Monaro was originaly published in Street Machine’s LSX Tuner magazine no.5, 2017

IT’S NOT exactly a happy pub discussion, but when it comes to the subject of life and death, most of us expect to have a lifespan into our 70s or 80s. But some unfortunate people know that, due to a health condition, their life expectancy might not be as long as their mates’.

Which brings us to the ownerof this sinister VZ Monaro, Jim Polentas. He’s a bloke who’s been given the news that he probably won’t be eligible for a bowling club membership. So for this Melburnian, every day above ground is a bonus!

Like many of us, Jim began playing with cars as a teenager, buying an HQ Holden Monaro. “They were cheap back then,” he says. “But it was expensive for a 16-year-old kid. It was my pocket money from working in my family’s restaurants.”

After four years with the Monaro, he followed up with a Torana GTR XU-1 before moving on to a fleet of family trucksters. But the old flame for another street machine flickered in the background.

“I’ve always had the desire and passion to build another car,” he says. “I’m trying to achieve everything I can before the inevitable happens. I was told at the age of 25 that my life would probably be much shorter than everyone else’s.”

One impressive aspect of this build is that it is 100 per cent street-legal, with Jim ensuring it was fully engineer-approved for road use in Victoria. “Since being built, I’ve been pulled over by the police and they have said how much they liked the car because it’s clean and neat. There’s not much showing and there’s nothing on the car that is too aggressive; it’s almost deceiving!”

Thankfully, the doctors weren’t quite correct, as Jim is now almost 50. Initial thoughts were to revisit the HQ Monaro or Torana from his youth, but with a blower and all the hardware. That idea soon went out the window though, with Jim instead deciding to use a modern Monaro, as it would be easier to build into a tough and legal machine.

The 5.7-litre all-alloy LS V8 has been pumped up with an intercooled Magnuson TVS1900 supercharger, VCM cam and upgraded valvetrain with PAC springs, Trend Performance pushrods and Rollmaster timing chain. Power? Jim isn’t sure yet, but 500 kilojobbies at the treads would be a good guess. Other goodies include an oil catch can and that beaut intake box. The Edelbrock covers are a nice touch, too

“I wanted something that would be fully road-usable and legal and that I wouldn’t be scared to drive,” he says. “I spoke to a couple of engineers and we soon decided the best way to achieve these aims was to modify a late-model Monaro.”

In 2015, Jim began searching for a suitable project CV8 on various sales sites. Finding a few, he broke one of the unwritten rules of car-buying by purchasing the first car he looked at in person — and again, by buying something modified!

“It was owned by an aeronautical engineer,” he explains. “Apart from a few stone chips the car was spotless and I could see it had been modified well. The car was low, it had head and cam work, a Di Filippo exhaust and an over-radiator intake system. It also had an upgraded stereo in it. I made an offer and the car was mine.”

Race Brakes in Yarraville provided the super-sized AP Racing 362mm-diameter two-piece front discs and 343mm DBA rears, clamped by AP Racing six- and four-piston calipers. Those wheels are 20-inch Simmons FR1s, staggered with 8.5- and 10-inch widths

Jim of course had big plans for his new toy, probably the most important being hassle-free street driving. “You have to build a car legally,” he reckons. “That’s the way it has to be. I wanted to be able to drive this car whenever I feel like it, without any fear whatsoever.”

Jim wanted the exhaust to be sized to drain the blown engine, but not too loud. The Di Filippo Big Boy extractors were already on the car when he bought it, but Full Flight Engineering’s chassis and suspension changes toward the rear meant a new exhaust from the catalytic converters back. With the VZ Monaro’s fuel tank mounted in the boot from factory, fitting dual pipes was easier than under most VT-VZs. Mission accomplished!

The Monaro had already been tweaked by Autotechnique to make 260kW at the treads when Jim bought it, but he wanted more. Big, easy grunt comes from supercharging, so Autotechnique installed a Magnuson TVS1900 supercharger, figuring it would be a great match to the head, cam and valvetrain upgrades they had done on the car for the previous owner. It did highlight a shortcoming of the CV8 platform, though.

The Monaro’s standard IRS has been replaced with a four-linked nine-inch in a tubbed rear. Sitting on QA1 coil-overs, a Strange Sportsman housing is stuffed with full-floater 35-spline axles, an Eaton Truetrac slip-limiting centre and 3.7:1 gears. As you can see, thanks to terrific fab work by Full Flight Engineering, the rear wheels and tyres fit within the lipped quarters with millimetric precision

“There wasn’t any power getting down to the ground,” Jim explains. “It was squatting too much and there was no power getting to the tyres. It was being lost and the car was skating in every gear.”

Potential fixes included mini-tubs and pumping the guards, but Jim opted to replace the stock IRS rear end with a tried-and-true street machining combo.

“We quickly settled on the nine-inch and four-link rear, which I was comfortable with,” he says. With 315-wide tyres and drag-style geometry under the guards, it has fixed the traction issue. “It doesn’t sit there wheel-spinning; in fact, it lifts the front.”

The blown 5.7’s power was beyond the ability of the standard 4L60E auto, so it was replaced earlier this year with a TH400 three-speeder, built by Matt at MDT Race Engines to cope with the supercharged torque. Autotechnique installed it with a 3500rpm TCE converter fronting it, controlled by a B&M Magnum Grip Street Bandit shifter in the Monaro’s original console.

The only other modification to the cabin relates to the fitting of the wheel tubs; the rear seat has been almost imperceptibly narrowed 50mm at each edge to fit.

One of the appeals of Holden’s early-2000s Monaro for Jim was the leather interior. He’s left it largely alone. The TH400 three-speed trans required a B&M shifter, and a small boost gauge has been added. The Monaro’s distinctive and supportive two-butt rear seat has been subtly modified to suit the rear wheelarch work, too

Jim’s not done yet, either! “It’s a fair way to go until I’m completely finished with it,” he reckons. He has plans for more cubes – a 383 stroker – and a bigger blower. Some people would drive the wheels off this thing, but Jim is more frugal with the use he gives his monster Monaro.

“I don’t take it out often, but I do take it out,” he explains. ”Most of the time it sits at home on its hoist. My little boy Manny has just turned 10 and it’s really his car because he’ll get it when I’m gone. If the weather’s going to be okay, I’ll get it out and cruise it to a car show with Manny and we have a great day!

“It’s been a great build,” Jim concludes. “Really, it’s been something of a blessing, very relaxing. I love this thing — it’s keeping me alive!”



Type: Holden 5.7L Gen III
Blower: Magnuson TVS1900
Cam: VCM billet VCM-21 217/225/113
ECU: Stock, HP Tuners flash-tuned
Fuel system: 1.5bar injectors, DeatschWerks pump
Exhaust: DPE Big Boy twin 3in, custom Full Flight Engineering cat-back

Gearbox: TH400
Converter: TCE 3200rpm
Diff: Custom 9in, Truetrac centre
Springs: King (f), Vogtland Racing (r)
Shocks: Monroe Sport GT (f), QA1 adjustable (r)
Brakes: AP Racing 362mm discs & six-piston calipers (f), DBA 343mm discs & AP four-piston calipers (r)
Other modifications: Custom mini-tubs, custom four-link live-axle rear end, custom tunnel, custom rear sway-bar

Rims: Simmons FR1 20×8.5 (f), custom three-piece Simmons FR 20×10 (r)
Rubber: Austyre Sport 225/35 (f), Nitto NT05 315/35 (r)