Gladstone based motorcycle tuners Alpha Performance Engines recently surpassed a milestone by successfully modifying a late generation Harley-Davidson Milwaukee-Eight powerplant to produce over 200 horsepower.
Custom made 4.5-inch cylinders with ductile iron sleeves and a 4.5-inch stroker crank combine to produce an engine displacing just over 143 cubic-inches, that equates to just under 2350 cc in the metric scale.
Fine tuning and development continues but on pump fuel the combination has already registered 202.92 horsepower and 171.73 ft-lb (233 Nm) of torque.
Even more impressive is that despite running some pretty big lobes on those special Cycle-Rama Inc CR578 camshafts the torque curve is still relatively flat with over 190 Nm available from as low as 2500 rpm.
Those big cams combine with what started out as standard Milwaukee-Eight heads before they were hand ported by Neil at Warflow Cylinder Heads to keep this big twin singing strong right through to 6750 rpm.
Over 200 horsepower is being made from around 6200 rpm right through to that 6750 which is as far as the guys are pushing things, so far…
A Screamin’ Eagle 64 mm throttle body with 8.2gps injectors sucks air through a Screamin’ Eagle Extreme Flow Heavy Breather and provides the significant sums of go juice through to an A.P.E. billet inlet manifold.
S&S premium lifters combine with Screamin’ Eagle adjustable push-rods while AV&V supply the valve springs.
A Wegner large diameter 2-2 exhaust was utilised for this run but the team at Alpha Performance Engines are going to experiement with some more variations on the camshafts and exhausts before arriving at their final specifications on this engine which pulls duty in a 2019 Harley-Davidson Road King Special.
Then when Benaraby Raceway opens up again the boys are going to shoot for nine-second quarters while retaining a stock wheel-base and clutch controls from this APE 143 powered streeter package.
MCNEWS.COM.AU is a specialist on-line resource that provides motorcycle news for motorcyclists. MCNews covers all areas of interest for the motorcycling public including news, reviews and comprehensive racing coverage.