Thread: How Much/How big? Air cleaners.

Tweet

Looks to me like Pro fleetline, rumrumm and 406Rich had it figured out before the question came up. Nice work fellows!

tech i purchased a street scoop for a single carb for my engine. It has a small filter that fits in it. i also had to remove some of my shroud to fit the bigger fan blades. is this enough to keep my engine cool?

Originally Posted by jyardgirl

tech i purchased a street scoop for a single carb for my engine. It has a small filter that fits in it. i also had to remove some of my shroud to fit the bigger fan blades. is this enough to keep my engine cool?

The filter shouldn't have anything to do with cooling the motor. It has to do with breathing and supplying enough air to make good power.

As far as the fan shroud, could you post a picture of what you did?

will tomorrow tech. thanks. what i meant to ask is the scoop filter enough for my engine to breathe and the shroud modification enough for my engine to cool.

A filter has to cause enough obstruction to particles in the air (dust, dirt...) but also needs to let air through.
The aperture size is very secondary here (because the aperture size of the carb is the real restriction to airflow at only a couple of square inches), it's the flow capability.
An air filter works like this: Its a fine mesh with very small holes in it. The smaller the holes, the better the filtering is going to be (i.e. less dirt in the motor = longer life). But on the other hand smaller holes will only let less air through. So to get a good flow of clean air you need very many very small holes. Easiest way to get more holes is to enlarge the area of the mesh. This is done by folding the filter material, thus fitting more mesh into the same aperture size.
Apart from the brand name K&N filters cost more because they use better filtering material (the material itself has more and smaller holes).

Much more important than the aperture size is to use a clean filter. Dirt clogs up open style filters quite quickly, because it stays in the small holes, as no air coming the other way (out of the carb) will blow it back out of the holes. Even unwashable filters can be cleaned quite well with compressed air blowing outwards from inside the filter (take it off the engine first or you'll blow dirt into it).

A typical filter will have a total area of 3 or 4 times the aperture size. Most open style filters suffice for street applications.

Note on scoops: The filter in scoops are mostly smaller all round, but have bigger foldes in them, so the mesh area isn't a lot smaller (if at all). After all, they are designed for scoops...

For tech's 6 square inch rule: Measure the length of one fold, multiply it by the height of the filter and by the number of folds (just count 'em).