For emissions or power, that is the question.
Typically, supercharged engines equate to increased performance in motorcycling circles. The word alone—supercharger—conjures up images of speed and power. Just look at Kawasaki’s H2 family, the only supercharged range on the market today. Its aggressive styling and face-melting speed only perpetuate supercharger stereotypes. However, the automotive industry has applied superchargers to meet strict emissions standards while preserving power. Sure, models like the Dodge Charger SRT Hellcat and Chevy Camaro ZL1 come with superchargers, but so do practical choices like Volvo’s V60 Wagon.
While we’ve seen our fair share of patents in the past, supercharged motorcycle engines are still rare. For that reason, Harley-Davidson's latest patent is particularly interesting. Issued yesterday, the patent outlines the Motor Company’s potential plan to integrate a supercharger into its Big Twin lineup. While the Milwaukee-Eight platform spans both Touring and Softail machines, the patent doesn’t specify whether superchargers will be fitted to current or future powerplants. What the documents do show us is the forced air induction apparatus and how Harley could implement the technology.
Gallery: Harley-Davidson Supercharger Patent
The numerous figures exhibit the supercharger itself (64), the mechanical pulley that powers it (88), and the supply and discharge ports (68, 72). In simple terms, the engine’s existing crankshaft powers the supercharger via a covered belt drive. When air enters the intake system through the filter and conduit, the pulley-driven supercharger compresses the incoming air before delivering it to the combustion chamber through the intake manifold.
Of course, with a belt functioning as the drive mechanism, stretching is inevitable. To eliminate slack in the system once stretching occurs, the supercharger latches to the crankcase on a self-adjusting mount. Equipped with springs and bushings, the slidable track maintains tension and reduces potential maintenance. The system seems simple enough but one question still remains: why?
Is Harley exploring supercharged engines for a future performance Big Twin? Maybe a new contender to the Indian’s King of the Baggers-winning Challenger? Or is the bar and shield preparing for future emissions regulations and inevitable modernization. Regardless of the answer, it's good to see more developments in supercharged engines. Hopefully, we’ll see more of those developments on spec sheets and less on patent documents in the future.