325hp Holden six with Phil Irving 12-port head

Our 2018 SMOTY winner gives his Phil Irving-equipped red motor a birthday

Photographers: Nik Judd

Ben Judd’s PRO EH took out the 2018 Street Machine of the Year award thanks to stunning bodywork, a very cool cruise-style interior and a stove-hot Holden red six. After racking up plenty of road miles, Ben decided it was time to give the cranky donk a look-over and make some minor changes.

“I pulled it out just to give it a refresh and tidy-up, and to change a couple of bits and pieces,” says the Judd’s Speed Shop proprietor. “It got a light hone and some new rings, and I changed to straight-cut gears on the cam instead of the helical gears.”

Having previously stomped out 325hp on Brad Tilley’s engine dyno, there wasn’t cause for a radical reinvention of the package, which starts off with an HQ-era red block.

“It’s about 208ci, I’d say,” says Ben. “The block is 20thou over with a slight offset grind in the crank to give it more stroke. It has a really old set of Yella Terra H-beam rods and forged SRP pistons. I’d estimate it is about 11.8 comp, but I did this combo a long time ago, so it can be hard to remember.”

The valvetrain features Crane roller lifters, hardened Crow pushrods and PAC small-block Chev valve springs with titanium retainers to suit the spicy Wayne Green solid-roller womp stick, which has 575thou lift and 264/255 degrees duration.

But the real sauce on this pie is the mega-rare Phil Irving 12-port alloy cylinder head. The fella responsible for the Repco V8 that Sir Jack Brabham drove to a Formula One World Championship, Irving only designed and made 25 Holden red six heads, and they’re hugely desirable today.

Irving also designed engines for Vincent HRD motorcycles, the legendary Repco Hi-Power crossflow head for grey motor Holdens and much more. You can read up on his exploits here.

“The exhaust ports have their own layout compared to a stock Holden six head,” Ben explains. “The intake ports also sit above the exhaust on a 45-degree angle, which helps make power. It does sound a little bit different to other Holden sixes – peakier than a stock Holden; more a Euro big six.”

The Irving head’s altered port layout required custom-made 1-3/4-inch headers, while the sump is an original pan modified back in the 90s by Haddad Race Cars & Engines to include a bigger well, built-in windage tray and internal gates. Other oiling changes include modifying the pump for improved flow and de-burring the lifter area to improve oil drain-back.

“We ran it on the dyno around 2009; at the time, it was the biggest power Brad Tilley had seen out of a Holden six,” Ben says. “He did say going from the 50mm Webers to 55mm units would make a bit more power, but at the cost of low-end torque, so we kept the 50mm carbs.”

While he was taking care of the finer details, Ben decided to make his 202 look as good as it could, using a whole tub of elbow grease. “I reckon I’d have spent a good two days de-burring the block, and then we primed it, high-filled it and rubbed that. Then there were a couple of days just in painting it! I also had the whole head smoothed and polished to look better.”