Help with calculation of how much air /air filter, an engine needs

Discussion in 'Lawn Mowing' started by MikeKle, May 12, 2010.

  1. MikeKle

    MikeKle LawnSite Platinum Member
    Posts: 4,253

    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
     
  2. jhawk60

    jhawk60 LawnSite Member
    from VA
    Posts: 241

    Air filter size in square inches = (CID X RPM)/20,839
     
  3. MikeKle

    MikeKle LawnSite Platinum Member
    Posts: 4,253

    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.
     
  4. unkownfl

    unkownfl LawnSite Gold Member
    Posts: 3,838

    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?
     
  5. unkownfl

    unkownfl LawnSite Gold Member
    Posts: 3,838

    I think that formula is wrong though. According to it my filter should be a 97 which is small.
     
  6. MikeKle

    MikeKle LawnSite Platinum Member
    Posts: 4,253

    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?
     
  7. unkownfl

    unkownfl LawnSite Gold Member
    Posts: 3,838

    The way I understand your post is you're switching the panel filter out for a canister style.
     
  8. jhawk60

    jhawk60 LawnSite Member
    from VA
    Posts: 241

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

    unkownfl LawnSite Gold Member
    Posts: 3,838

    Ok gotcha I thought it was for maximum performance.
     

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