One of the most dramatic improvements in the look of the Victory motorcycle is getting rid of the coffin lid air box. It is relatively cheap, and easy. It also gives the bike a more custom looking stance. Unfortunately it is also very misunderstood. Today's discussion will deal with air management as it applies to Victory, but I will have to use examples from the automotive, and other bikes.

Do to size constraints air intake on most bikes are a compromise. You need 2 totally different systems to achieve perfect balance, and there just is not enough room. First you need a long small diameter tube for high velocity air at low RPM torque. then you need an open low restriction chamber for high RPM power

In a car they have plenty of room, and in fact many newer cars use what is called a dual path intake. Using a valve that opens at a set RPM. They essentially have 2 intake manifolds in one place.

On HD they use a different approach. There they use an intake that is like a reverse 2/1 exhausts. It takes air through a single central pipe and then splits it at the heads. This produces reasonable power throughout the rev range, since having both cylinders draw into one source does increase the velocity. However as RPMS go up each cylinder now has to compete for its air.

Now we come to the Vic. Victory uses a dual throttle body with a relatively large diameter intake runner between the throttle body and the intake valve. The 99 had a large volume open-air box that worked just fine. However the engineers determined that most riders would ride at the bottom of the rev scale [not this rider]. They also were not planning for future upgrades in power. This is why we have the tubes in the air box. What they do is act like long narrow intake runners. This promotes high velocity air columns to each cylinder. While it works it has a few draw backs. First the gain is only a few ft lb, and only at low RPM. Next you effectively have 2 trumpets under your tank producing lots of noise. After that you have a very poor shape right where it enters the throttle body making lots of turbulence in high RPM runs. Finally the whole thing becomes a restriction as you go past mid range the tubes are to small.

Now lets look at the aftermarket stuff. These are all open systems. Yes you will loose a couple of ft lb below 2500RPM,but even with the worst the e

xtra volume will give you more horsepower, and torque above 2700.

There are essentially only three systems available. 99Vic/Santarosa/Ness. These are all 99-air boxes in different packages. The Vic part is cheapest, but you have to find your own bolts. the other two provide hardware, and instructions for about $100. The 99 box works reasonably well, but the shape at the inlet causes a little extra turbulence. So if you are after absolute power it is not the best choice Eagle Cat uses a 360-degree intake on a shaped plate. It promotes a little better velocity, and relatively low turbulence, and abundant volume for high HP pmrt has an air box which has not been tested on the Freedom motor. It however is the first one to get over 125 HP on the older style bike. I have one, and will be installing it on my bike in the next couple of weeks; it is also a 360 filter. But it has a thick plate with rounded edges to promote better velocity for low RPM.

I personally have ridden freedoms with both the 99,and the Eagle cat. With both styles I could not "feel' any difference in low end performance, however one bike with an Eagle cat, and a Lloydz VFC was noticeably stronger above 3000 RPM. On the dyno both air boxes showed a SMALL drop in idle to about 2500,but both were at least as strong above that. The Eagle Cat a little better the whole way. While you don't need a VFC for these applications, Installing one WILL boost both HP, and torque. If you really feel that you NEED that small amount of lost power. Switching to a 2/1 exhaust will bring it back, and give you more all the way.

As I said earlier I will be trying a pmrt box in the next couple of weeks, and will show before and after results as well as after a VFC.

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