Here at Baggers, we've seen firsthand the incredible power results that can be had from adding a supercharger to a naturally aspirated V-twin engine. Bolting on a 50-65 percent performance boost in an afternoon is certainly something that would pique any power junkie's interest, especially a motorcyclist. ProCharger has been making superchargers for the automotive, marine, powersport, and most importantly, motorcycle (Harley-Davidson) industry for many years, and because of its longstanding success with breaking time trial records, the company has established a very reputable name in the performance game.
This specific ProCharger model ($5,495) is a centrifugal belt-driven supercharger. Available for '99-later Harley-Davidson Touring models and including a side-mount intercooler, the ProCharger increases the density of the air/fuel charge in the engine's combustion chamber, therefore increasing power. The pressure differential between the intake manifold and cylinder create greater mass of air than atmospheric pressure alone (14.7 psi) to flow into the cylinder. This is called charged air. The ProCharger is driven off of the crankshaft via a cog pulley to increase boost as rpm increases, making boost immediately available as you roll on the throttle. What's boost? It is pressure above 14.7 psi. ProCharger recommends adding around 10 psi of boost to the engine's intake-a 110ci Twin Cam in this case. Now you take the sum of the 10 psi with the 14.7 psi of atmospheric pressure and you have a total of 24.7 psi entering into the engine through the induction system. Now that's a lot of air at a very rapid rate.
And because the air is traveling at such a higher velocity and there's simply more of it, an intercooler (which comes with this kit) is essential for optimum performance. The reason for this is pretty simple: cooler air is denser. An intercooler lowers the temperature of the charged air when it enters the intake. Because cooler air contains more oxygen, and since only pump gas is required (91 octane) the risk for potential detonation is reduced. Detonation is no bueno. As the blower shoots air into the engine it passes through the intercooler assembly, which reduces the air temperature before it flows into the throttle body, ultimately into the engine.
Because the 2012 Harley-Davidson Road Glide receiving the power addition was going for the completely blacked-out aesthetic, we ordered up a flat-black powdercoated ProCharger. Knowing a thing or two about superchargers in general, we headed over to Huntington Beach Hogs & Choppers in you guessed it, Huntington Beach, California, for the installation. Owner Ed Syer and his trusted associates have been power junkies since birth. Making baggers go faster-or anything with an engine for that matter-is what HB Hogs is all about. We were able to complete the installation in about six hours, making it a real deal easy installation. Next issue, we'll provide horsepower and torque numbers once we bolt on a brand-new Vance & Hines Monster Rounds exhaust system along with a Power Commander made specifically for the ProCharger unit. Stay tuned, this baby should make about 150 horses!
01. Here's a bird's eye view of all the components necessary for installation. As you can see, this might look intimidating to the average builder, but it really is a relatively easy installation. And best of all, ProCharger provides a very comprehensive set of installation instructions that a novice could understand.
02 to 06 The following make up the meat of the ProCharger assembly: front and rear views of the supercharger (A), air-to-air intercooler system (B), outer primary cover (C) that comes assembled but needs to be disassembled for installation, and the air cleaner assembly (D).
07 ProCharger's kit includes AIM Corporation's Variable Pressure Clutch, a lock-up clutch that can handle up to 200hp and bolts directly to the factory clutch.
08. We started with the primary side of the bike by draining the primary fluid and removing the outer primary cover in order to...
09. ...install the Power Take-Off (PTO) assembly, which consists of this driving cog pulley that we installed onto the compensating sprocket.
10. After the cog pulley was bolted on, the AIM VP ProCharger clutch was installed over the factory clutch assembly. The VP kit includes the Variable Pressure Clutch, which is a lock-up clutch to provide stronger clutch engagement while reducing clutch lever effort; also necessary for a substantial power increase like this supercharger.
11. The ProCharger primary cover was installed over the driving cog pulley and AIM VP kit. The new primary will also act as the mount for the supercharger itself, which will later be attached near the top-left of the ProCharger primary cover via the ProCharger bracket assembly.
12. Next, we mounted the eccentric tensioner assembly in place (arrow), and once it was installed, we were able to set the proper PTO belt tension with a tensioning jig and tension tester. The Kevlar belt was placed around the three pulleys in order to get ready for testing.
13. By placing the tensioning jig over the PTO assembly we used a machinist scale (ruler) and the supplied tension tester in order to achieve the proper tension. Sliding the rubber O-ring on the tension tester to about 6-6.5 pounds of force, we were ready to make our adjustments. We placed the tension tester against the back of the Kevlar belt. Once we were within our desired 3/32 to 1/4 inch deflection with the ruler, we tightened down the eccentric tensioner assembly to 18-22 lb-ft of torque.
14. We removed the tensioning jig and installed the ProCharger PTO cover. We then poured in a quart of primary oil and installed the primary derby cover using the supplied torque sequence to tighten all the primary bolts down to ProCharger's specs.
15. We had to remove the left-side floorboard in order to install the supercharger. With the serpentine-style belt already positioned on the back of the primary cover, we mounted the ProCharger to its supercharger bracket and installed it to the back of the primary cover. We slid the belt around the pulleys on the ProCharger (A), the idler pulley (B), and the primary cover pulley (C). With the belt hooked up, we moved over to the right side to install the bonnet assembly (ProCharger's air cleaner). But first...
16. ...we needed to remove a few items like the air cleaner and throttle body/intake manifold assembly.
17. With the throttle body removed, we were able to install the new, larger, higher-flowing fuel rail and fuel injectors. These are included in the ProCharger kit to compensate for the increased amount of air being produced by the supercharger.
18. We reinstalled the throttle body and intake manifold and tightened down the bonnet's backing plate.
19. With a new high-flow air filter like this one designed specifically for ProCharger's Bonnet assembly, we were one step closer to being done.
20. After tightening down the bonnet assembly cover, it was time to install the intercooler unit, which connects the bonnet assembly to the ProCharger.
21. In order to connect the two, we installed the silicon hoses from the ProCharger between the frame's downtubes and front cylinder to the intercooler, ultimately to the bonnet assembly. After the fit was where we wanted it, we snugged down the hose clamps.
22 & 23 Last to be installed to the ProCharger assembly was the surge valve, which allows boost to be bypassed from the engine under idle or cruising speeds so that the bike performs like a bat outta hell while still delivering good fuel efficiency and a smooth ride overall. The surge valve is usually left open but if it detects engine load going from normal vacuum to boost, the valve closes and boost is directed into the intake. When decelerating, the valve opens again so that the remaining boost can be expelled.
24 & 25 Here's where we'll leave off for this installment. The supercharger assembly itself is now complete and ready for a kickass exhaust from Vance & Hines as well as some fine-tuning from the supplied Power Commander that came with the kit. Tune in next month for the dyno runs, which should be pretty astronomical if all goes well.
14801 W. 114th Terrace
Vance & Hines
13861 Rosecrans Ave.
Santa Fe Springs
Huntington Beach Hogs & Choppers
15631 Graham Street Unit C.
16631 Gemini Lane