Generally speaking, in order to increase an engine’s output of power, the amount of air and fuel must increase. With the exception of V-Rods, Harleys have relatively low-revving power bands and all OE parts only have two valves per head. Meaning you can’t rev them much past 5,000 rpm and expect them to make more power by increasing rpm. Larger displacement will usually increase power, right? There’s even an old racer’s adage that claims there’s no substitute for larger volume, but what happens when you run out of room? Stock bores can be enlarged, and strokes can be lengthened, but only to a point. There are limits to the maximum size of an engine that will fit in a stock frame. Plus the costs continue to rise with ported heads, larger cylinders, longer rods, and wider pistons; it’s expensive to get close to the naturally-aspirated performance ceiling. Astronomical compression ratios add power, too, but won’t run on pump gas, and high-octane race gas is far more expensive (if you can find it) than the premium at the local fuel stop. Additionally, reliability issues start to develop and bottom ends need to be strengthened—all pitfalls that average speed-freaks want to avoid.
When larger displacement and more revs are no longer options for increasing power, power-adders, like nitrous, turbos, and superchargers, are the solution. All three examples will increase power, but in the case of beefing up a stock Harley, the supercharger is an excellent choice. Superchargers deliver great power across the entire power band; the power is “on-tap” and requires no lag time like a turbo; instead it features instant throttle response. And there’s no going to the store to buy refills of go-fast juice like with nitrous (or running out just when needed most).
How does a supercharger work? A normally aspirated engine pulls air into the combustion chamber with the downward stroke of the piston. Essentially, a centrifugal supercharger uses a crankshaft driven impeller to create a high-pressure system of compressed air that is pushed into the combustion chamber whenever an intake valve is opened, complementing » the vacuum created by the downward stroke of the piston. The compressed air requires additional fuel and the denser fuel/air charge makes a more powerful explosion when ignited, that is, versus a naturally aspired engine.
ProCharger’s Bolt-On kit claims at least 40-80 more horsepower. That statement alone is enough to get a performance junky’s blood flowing, yet it begs the question, “How is ProCharger’s system able to make claims that seem to be well beyond the reach of its competitors?” According to ProCharger, its centrifugal supercharger is able to produce so much more than other systems because of its integrated intercooling systems—simply put, ProCharger’s system is better able to use compressed air by cooling it off. Cooler air is more condensed than heated air, and therefore increases performance. By using cooler air, close to stock (or stock) timing is also retained, speeding up the installation process and leaving the installer with one less thing to do. »
Curious to see if ProCharger’s performance claims were true, a test of its kit was in order. Huntington Beach Hogs and Choppers in (you guessed it) Huntington Beach, California, happened to have a test mule ’11 Twin Cam 96ci Dyna it was willing to donate for the cause, and has performed a few supercharger installations in the past. HB Hogs also houses its own dyno for testing the results. Designed specifically for use on H-D Twin Cam EFI-equipped bikes, the ProCharger kit comes with everything needed to upgrade the bike and get it back on the road in about a day. Each kit includes the B-1 ProCharger supercharger (assembled), complete air-to-air intercooler system, supercharger bracket, outer primary cover, air-filter cover, belt tensioner, surge/bypass valve, computer programming module, air-filter, belts, hoses, gaskets, and hardware. Follow along as the major aspects of the ProCharger system are explained in this first installment. Next issue will cover tearing into the bike and dyno tests proving the power that was added! HB
(714) 848-3030 | aim-tamachi.com
(714) 891-7207 | www.hbhogs.com
(913) 338-2886 | www.procharger.com