The Homegrown Horsepower segment has turned into one of the fan favorites here at EngineLabs, and in this installment Jed Sladden’s Keith Black HEMI engine makes an appearance. The engine was built by Sladden’s best friend, Aaron Beddall, in Sladden’s home garage in Brisbane, Australia.

For a solid base, the pair turned in the direction of a Keith Black/Milodon engine block, used here in a water-cooled configuration. This block is unique in that it uses a split main section, which required special considerations during construction. Those include the chamfering and radius Beddall needs to put on all of the main bearings prior to installation, as the oil is fed to the lower main shells through the cradle. The cradle increases the strength of the engine block exponentially, which is helpful when huge power is the goal.

Beddall subsequently filled the block with a 4.250-inch stroke Keith Black billet crankshaft that swings 7.100-inch custom Oliver billet connecting rods. He’s also selected Venolia coated pistons to sit in the 4.280-inch bore, circled by Childs & Albert dykes-style piston rings that are used to control the oil in the crankcase.

Keith Black cylinder heads ported to Stage 5 specs sit on top, with factory HEMI 1.7:1-ratio heavy-duty rocker arms in place actuated by a COMP Cams solid-roller camshaft and heavy-duty lifters. The camshaft measures .772-inch intake and .784-inch exhaust lift, and copper head gaskets help to keep the cylinders sealed.

At only 488 cubic inches, the engine is not large, but when the engine is pumped up by a pair of Turbonetics 106mm turbochargers, there isn’t much need to go larger. Tuning is handled by Robert Novak of Definition Motorsport with a MoTec M8 engine management system controlling a set of Moran Motorsports 500 pound-per-hour fuel injectors along with an MSD 10 ignition system and coil.

The methanol fuel permits a cool intake charge without the use of intercooling; with only 20 degrees of timing, the engine puts out 1,247 horsepower at the wheels with only 12 pounds of boost on tap. Increasing boost pressure to 16 psi, the engine shows close to 2,000 flywheel horsepower. The turbochargers aren’t even close to being tapped out at that boost level – there’s plenty more hidden in the combination as the team sorts out the car.

Controlling the massive airflow from the turbochargers is the job of the custom 90mm wastegates and 75mm blowoff valves, while the fuel is supplied through four – yes, four – Product Engineering alky fuel pumps. There’s also a custom intake manifold that is based on an Enderle mechanical-injection setup and has been heavily modified for this application.

There are many other custom touches on this engine, which resides in Sladden’s Australian AP5 Valiant and is even driven on the street from time to time. Race weight is a whopping 3,990 pounds across the scales with driver, mainly due to the use of what Beddall calls “overboard chassis strengthening” to handle the massive amount of power produced – and this engine’s turned way down compared to its capabilities.

The car uses a Powerglide transmission for strength and performance; with a 3.55 gear in the rearend it’s been a best of 8.55 at 169 MPH with much more on tap – the team is trying to sort out a transbrake issue and has only been able to leave off the footbrake for now.

The motorsports scene in Australia is huge, with is remarkable when exchange rates are taken into the equation, along with the high prices for shipping parts from here to there. And the enthusiasts don’t seem to skip a beat in the search for horsepower, as evidenced by the engine in Jed’s beast.

If you have a homebuilt engine that you’d like to share with EngineLabs readers, just drop us a line. High-quality photos and information are helpful.