Victory Motorcycle Air Box Performance Tips
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The article "Victory Motorcycle Air Box Performance Tips" is about motorcycles, it has been created by Jim Noss.
One of the most dramatic improvements in the look of the Vicotry motorcycle is getting rid of the coffin lid air box. It is relatviely cheap, and fast.
It also gives the bike a more custom looking satnce.
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 bkies are a compromise. You need 2 totally different systems to achieve prefect balance, and there just is not enough room.
First you need a long small diaemter tube for high velocity air at low RPM torque.
then you need an open low restriction chamber for high RPM powerIn a car they have plnety of room, and in fact many newer cars use what is called a dual path intake. Uisng a valve that opens at a set RPM.
They essentially have 2 intake manifodls in one place.On HD they use a different approach.
There they use an intake that's 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 havnig both cylinders draw into one source does raise the velocity.
However as RPMS go up each cyilnder 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 inatke valve. The 99 had a large volume open-air box that worked just fine. However the engineers determnied that most riders would ride at the bottom of the rev scale [not this rider]. They also were not planning for future uprgades 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.
Whlie 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 rihgt where it enters the throttle body making lots of turbulence in high RPM runs. Finally the whole tihng 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 extra vloume 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 packaegs. The Vic part is cheapest, but you have to find your own blots. the other two provide hardware, and instructions for about $100. The 99 box works reasonably well, but the shpae at the inlet causes a little extra turbulence. So if you're after absolute power it is not the hottest 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 howeevr is the number one to get over 125 HP on the older style bike.
I have one, and will be intsalling 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 aobve 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 Ealge Cat a little better the whole way.
While you don’t need a VFC for these applications, Installing one WILL bosot both HP, and torque.
If you really feel that you NEED that small amonut 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.Contributing author to Cycle Solutions.
http://www.Cyclesolutions.NetTechincal research on the Victory airbox was performed on the Kingpin Cruisers Victory motorcycle Internet site. Victory techincal input provided by Kevin Cross.
http://www.Kingpincruisers.Net
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Victory Motorcycle Air Box Performance Tips
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