Turbo engines might make race-winning power, but for a street car, it’s hard to beat the visual appeal and fearsome bark of a towering, tall-deck big-block wearing an enormous Roots supercharger.

In recent years, Sydney’s ProFlo Performance has been the go-to workshop for these sorts of in-your-face blown combos. The Campbelltown-based shop has almost single-handedly kept the pro street fires burning in the Harbour City, as exemplified by this saucy, 14/71-blown fatty.

“The plan was always to use big cubes so it doesn’t have to rev hard while also making enough horsepower and heaps of torque,” says ProFlo’s Paul Sant of this monstrous yet relatively simple donk. “It’s going into an HQ Holden that will be a street and event car, so it has to cruise but also handle what will get thrown at it an event like Powercruise.”

You might expect a combo destined to get beat on would need exotic internals, but there are no alloy rods or mega-dollar billet crankshafts here. Based around a Dart Big M iron block, the combo swings 632 cubic inches thanks to a Callies steel crank and rods, with 10:1 JE pistons to suit the E85 intended for this set-up.

“Having it reliable and easy to service is really important on these sorts of engines, so we pushed the cubes and kept everything else pretty easy,” Paul explains.

Of course, no tough street engine worth its salt would run anything other than a solid-roller camshaft, in this case a custom Bullet-grind stick working BAM bushed lifters. “We’ve gone with a big solid-roller to make power, even though we’re not after ultimate power,” Paul says. “It isn’t anything too wild, but we won’t have to try too hard to produce plenty of grunt.”

The AFR 385cc heads wear Jesel rockers and Shaun’s Custom Alloy covers, but the real party-starter is the enormous billet BDS 14/71 standard-helix blower.

“On 10-12psi, it should make 1300-1400hp, and that’s the benefit of big cubes,” says Paul. “Because it’s going into an HQ, I think it’ll have 2.25-inch primaries to get the gas out, but we’ll see.”

While many street engines making four-digit power run dry sumps, this rat motor’s low-stress focus means a Milodon wet sump works just fine and keeps things simple and reliable. Similarly, an off-the-shelf Melling Select oil pump will get the job done with aplomb and not complicate the front-drive accessories, which includes a custom crank trigger wheel for the EFI set-up.

Once this behemoth is slotted into the customer’s HQ, we’ll hopefully get to hear its siren song at events before too long!

MAD HATTER

The enormous 14/71 pump is topped by one of ProFlo’s own PFP billet hats. While the metering block and lines may suggest a traditional, mechanically injected set-up, this bad boy is run by computers. “We do EFI and mechanical hats,” says Paul. “A FuelTech FT600 ECU is used to run this engine.”

ProFlo Performance
Campbelltown, NSW
profloperformance.com.au