427-cube twin-turbo Windsor – Mill of the Month

Here's a new story to file under: ‘Builds That Got Out Of Hand’

Photographers: Will Horner

This article was originally published in the March 2019 issue of Street Machine

THE king-sized donk that graces the engine bay of Marko’s XA Fairmont started out as a simple turbo Windsor deal, but has escalated into a potential 1500hp belter.

The GT-spec sedan was built by esteemed car crafter Howard Astill, while the motor was pieced together by Sam Fenech from Westend Performance. Although Marko is somewhat aloof when discussing his horsepower goals, he says there’s solid reasoning behind his decision to combine V8 goodness with forced induction.

“I went for a ride in a mate’s VK Commodore with a single turbo bolted to the 5.0-litre, and the way it could blaze tyres at speed was amazing,” he says. “When I decided to build this one I wasn’t going to muck around with all this aspirated stuff.”

He certainly didn’t muck around, instructing Sam from Westend Performance to fill the donk with all the fruit. On the menu was a 427ci World Products Man O’War cast-iron block, with a Callies crank, Oliver rods and Diamond pistons. One of the more unique parts of the build is the use of Torrington thrust bearings to help keep the rotating assembly from playing ping-pong in the bottom end. The boys from Westend also fitted an external Peterson R4 belt-driven oil pump to keep the wet sump system up to scratch.

A pair of AFR 225cc heads assist the custom-grind solid-roller Comp Cams camshaft in allowing the engine to breathe, with a Wilson Manifolds throttlebody and Edelbrock intake manifold up top. A pair of BorgWarner S300 turbos feed the beast, with Marko planning to turn them up to 15psi. Fuel will be the juicy corn of E85 being pumped through a set of 1600cc injectors, with a Holley Dominator ECU used to control the madness.

twin-turbo windsor mill

While the car and engine made an appearance at MotorEx in 2017, the engine wasn’t finished, and at the time of writing still hadn’t had its full first test hit. Plans are afoot to run it up on the chassis dyno shortly, and with figures north of 1300rwhp thrown around by people in the know, it should be one stout performer.

Marko mainly plans to cruise it like a boss, but the allure of the drag strip is never far away.

“It was always going to be a street car; it’s not going to be overly loud and the car doesn’t have a ’cage or anything like that,” he says. “But I might take it out to the drags at some point.”


THIS mental donk will be lovingly placed into a beautifully crafted XA sedan built by long-time Ford fettler Howard Astill. A special build, #013 in the Astill collection, we look forward to bringing you a full feature on the Falcon once it’s bolted back together.