Mark Riek ups the grunt in his turbo grey motor-powered FX ute


IN 1953, when Mark Riek’s FX Holden ute originally rolled off the production line equipped with the 132ci straight-six grey motor, it made just 60hp. That doesn’t sound like much, but for a nation used to driving underpowered Pommy cars, the first Holden was a revelation and sparked off a massive performance industry.

 By the time the grey motor was replaced by the red motor (with the release of the EH in 1963), there had been a bewildering array of hot up goodies developed for the grey, including the Repco crossflow head, a number of twin cam conversions and supercharger kits. Hot grey motors were used in circuit racing, speedway, drag racing, boats and street cars and in many ways, they were as popular then as the LS is today. By the early 70s, the red motor and V8 engines had eclipsed the venerable grey and only the diehards stuck with it, including Bob Hamilton in his Captain Nitrous FJ.

 Even today, there is a small band of enthusiasts who persist in trying to squeeze horsepower out of the old sideplate six, including Mark, who has built a turbocharged EFI set up for FX ute. We featured the car in SM, June 2015 and Mark has recently given the engine a birthday. Upgrades have included a bigger turbo, plenum and throttle body, an upgraded fuel system and ignition system and a switch to E85 fuel. He also replaced the Trimatic gearbox for a two-speed Powerglide.

The internals remain as built by Geoff Scott, though Mark has added Yella Terra roller rockers and a Gilmer drive. The motor displaces at 150ci with Mitsubishi 4G64 conrods, Mazda pistons, a Waggot cam and a heavily-modified factory crank.

 Rod Salmon at the Speed Shop in Gympie handled the recent upgrades to the external power-adders. The turbo is now a Garrett GTX2863R, which blows through a PWR water-to-air intercooler and a larger custom plenum equipped with a Plazmaman 60mm throttlebody. Ignition is handled by a sequential distributor with six LS1 coils, while the E85 juice is delivered through a set of 410cc injectors. The ECU is a MoTeC M84 and on 17lb of boost it made a very stout 204rwhp.

“The injectors are maxed-out at 17psi,” says Mark. “We may fit bigger injectors if I need more power to get the quarter mile times I’m hoping for. I’d like to beat Captain Nitrous, which ran a 12.98-second pass back in the day.”

To read the full feature on Mark Riek’s FX Holden ute, click here.