MILL OF THE MONTH

400CI BLOWN & INJECTED SMALL-BLOCK CHEV

S T O R Y A N D R E W B R O A D L E Y P H O T O S C H R I S T H O R O G O O D

> WESTEND PERFORMANCE CAMPBELTOWN, NSW

WHAT better way to power a freshly rebuilt HK Monaro than with a 1000hp, Whippleblown small-block? The larger radial-entry Whipple superchargers are fast emerging as an alternative to traditional 71-series blowers, and as Sam from Westend Performance explains it, that’s for good reason.

“This customer wanted to make over 1000hp on pump gas, and in my experience, intake temps end up too high with an older-style Roots blower,” he says. “To get an 8/71 to make 15psi on this engine we’d have to overdrive it at 12-15 per cent. It would then be operating well out of its efficiency range, whereas this Whipple 510R should make 20psi at 1:1.”

The 510R is a powerful unit – an 8.3-litre twin screw blower that Sam says is roughly equivalent to a 14/71 blower in terms of potential horsepower output. It’s also largely interchangeable with a 71-series blower in that it will bolt to a traditional Roots manifold and accept a Roots-style drive snout and injector hat, or carby adaptor.

In this instance, Sam has opted for an Enderle bug catcher fitted with a Joe Blo EFI system and Siemens injectors, controlled by a Holley ECU.

The engine itself is 400ci in displacement, with a Dart Little M block, Callies Magnum crankshaft, Callies Ultra conrods and JE pistons. The heads are AFR 245 alloy units and the camshaft is a Crane mechanical-roller, which communicates with the valves via Aussiemade Jet Engineering pushrods and a set of T&D rockers. Oiling is handled by a billet pump and Moroso pan, while an MSD distributor provides the spark.

Sam is yet to dyno the engine, but is confident that the customer’s 1000hp ambitions should be realised on pump fuel, with the output climbing to around the 1200hp mark on E85 – a pretty healthy little small-block indeed.

“The Monaro will primarily be used as a street car, so it should be nice and driveable, too,” says Sam. s