Air Cleaner Question

Small Block Mopar Engine

  1. olddman

    olddman Well-Known Member

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    Just wondering if there is any difference in performance or air flow between an original equipment 10 inch un silenced air cleaner for a 1965 four barrel 273 and using an after market air cleaner, say a K&N?
     
  2. 66fs

    66fs FABO Gold Member FABO Gold Member

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    I doubt it. The factory air filter will keep the inside of your engine cleaner.
     
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    • Bewy

      Bewy Well-Known Member

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      There is likely a substantial difference.
      D. Vizard did extensive testing of ACs to ISO 5011 standards. K & N tested against two similarly sized filters: K & N 440 cfm, others 378 & 351.
      Not only did the K & N flow more , but it was more efficient at dust removal, 97%. Others, similar size: 50.8%, 93.9%, to as low as 25.9%. &
       
    • furrystump

      furrystump Well-Known Member

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      Depends on power level. You can pretty easily start to out flow a stock un-silenced air cleaner. Stock they have about 3/4” gap at the bottom multiply that by the circumference of the air cleaner and it doesn’t add up to much. I think a stock 340 diameter is 12”? 12”x3/4”=a whopping 9 square inches!! Open 3” tall air cleaner. 3”x12”=36 inches. At 410 CI around 400 hp it started to become an issue for me. My AFR’s at higher rpm would fluctuate wildly. I skeletonized the base in the angled area, not the horizontal area where it enters the carb. Smooth transition is very important. They are now rock steady up to as high as I have the guts to rev it. Across all the makes stock air cleaners become problems in FAST. Even the big Hemi ones. They just were not designed to flow 500+ CI at 8,000+ rpm.
       
    • furrystump

      furrystump Well-Known Member

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      I thought about building a 1st gen barracuda for FAST. I just couldn’t get by the intake/exhaust manifolds and number 3 on the list was the air cleaner.
       
    • 33IMP

      33IMP Well-Known Member

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      For a slightly warmed 273, i would think the stock unsilenced would be fine. If you are worried about it, and you have hood clearance, run a taller, same diameter element.
      Engine masters ran an element/housing test on a 700 hp. engine, and decided from the results how much each could be expected to support. Even the very worst one tested, could support 300 hp.
       
    • pishta

      pishta I know I'm right....

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      The K&N NEEDS TO BE OILED to work properly. Most newbys run them dry. They dont work well dry.
       
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      • grimreaper

        grimreaper Cross Member

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        Get the salad bowl!!!
         
      • furrystump

        furrystump Well-Known Member

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        Salad bowl for the win!!
         
      • pishta

        pishta I know I'm right....

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        we ran nothing for years, so cal...no rain. no dirt roads....no paint!
         
      • RustyRatRod

        RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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        Now there'll be salad bowl air filters poppin up everywhere.
         
      • 66fs

        66fs FABO Gold Member FABO Gold Member

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        Your math is wrong. Area of a circle is Pi x r squared. You have to calculate both circles and subtract the smaller circle. The Commando air cleaner is about 11 inch OD minus about 10 in OD it comes to about 16.5 square inches.
         
      • furrystump

        furrystump Well-Known Member

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        Not sure about 273, but I would be surprised if the gap was an inch on a 340. My fat, but not sausage finger doesn’t fit in the gap.
         
      • 66fs

        66fs FABO Gold Member FABO Gold Member

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        273 gap is only about 1/2 inch. Only 1 inch on the diameter. Not saying you didn't need to do what you did based on your experience.
         
      • furrystump

        furrystump Well-Known Member

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        I took math for poets in school!:):)
         
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        • 66jim

          66jim Well-Known Member

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          Your engine needs cold air, the test has no control over temperature. Anything less than a cold air setup is losing power. Even chassis dyno tests have the hood open, not real world.
           
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          • olddman

            olddman Well-Known Member

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            Thanks for all the input from everyone. I was just thinking about going back to the original air cleaner used on the 273 Commando engine. Had a 1965 Dart GT years ago and now that I have another one thought it might be nice to have an air cleaner that came on the Commando I had back in the day.
             
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