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View Full Version : Help with calculation of how much air /air filter, an engine needs


MikeKle
05-12-2010, 11:40 PM
I remember a formula on here that you could calculate the amount of air an engine needed to breath easily when switching air filters? I believe you take the cc's of the engine and divide by the area of the air filter or something like that??? Not sure, is there even such a formula? I am putting a canister type filter on a FH580V kawi engine and it had the regular paper filter from the factory, some models of the 580V DO come with the canister filter, so it should work, but Im not sure if those models are using a different carb? Thanks

jhawk60
05-13-2010, 12:03 AM
Air filter size in square inches = (CID X RPM)/20,839

MikeKle
05-13-2010, 12:29 AM
If something was not getting enough air, you would know as soon as you fired it up...right? Ive heard it will make a strange sound right away if somethings not right or needs to be adjusted.

unkownfl
05-13-2010, 12:31 AM
You'll see the filter start to shrink or the inlet tube starting to fold in on itself. Why would you put a smaller canister filter on over the panel though?

unkownfl
05-13-2010, 12:35 AM
I think that formula is wrong though. According to it my filter should be a 97 which is small.

MikeKle
05-13-2010, 12:39 AM
You'll see the filter start to shrink or the inlet tube starting to fold in on itself. Why would you put a smaller canister filter on over the panel though?

The canister is actually pretty big, came from a Yanmar 3cyl diesel engine.Inlet opening is 2" dia. Not sure what panel you are talking about?

unkownfl
05-13-2010, 12:41 AM
The canister is actually pretty big, came from a Yanmar 3cyl diesel engine.Inlet opening is 2" dia. Not sure what panel you are talking about?

The way I understand your post is you're switching the panel filter out for a canister style.

jhawk60
05-13-2010, 12:47 AM
I think that formula is wrong though. According to it my filter should be a 97 which is small.

That formula is from K&N's website, so I doubt it is wrong. It is for the minimum size filter for an application.

unkownfl
05-13-2010, 12:49 AM
That formula is from K&N's website, so I doubt it is wrong. It is for the minimum size filter for an application.

Ok gotcha I thought it was for maximum performance.