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Intake air box/filter

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  • Intake air box/filter

    What part have you guys used for your intake air box? I'm likely going fuel injected, but still need an intake box with a filter housing. Is the Cessna style with a Brackett filter the best way to go? Can the carb heat port be used as alternate air?


  • #2
    I used the Vans FAB box. Glassed and riveted to the cowl. I have a carburetor but it worked out pretty well.

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    • #3
      Yeah, being a former Cessna 170 owner, as well as having removed/replaced the cowling on a CubCrafters aircraft, I'm not sure which I prefer: The Brackett style sealing against the opening the cowl, or the formed opening that attaches to the intake with scat hose. I'd be curious to see others' solutions.

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      • #4
        I designed my own airbox and welded it out of 0.032 steel. Yes, it is heavier than aluminum, but the fatigue resistance and repairability is far superior. Hanging on the end of a carburetor (or fuel control) is a VERY high vibration environment. I can't say this is the best solution, but it is what I did.
        Russ Erb
        Bearhawk #164 "Three Sigma" (flying), Rosamond CA
        Bearhawk Reference CD
        http://bhcd.erbman.org

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        • #5
          If your not in a hurry for a carb air box you might wait a month. There may be something better coming. I have it on pretty good authority.

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          • #6
            Has anyone used the Sam James filter kit for an IO-540 that uses a K&N filter? Here is a link to his web page. http://www.jamesaircraft.com/?page_id=43
            Larry Driver
            Bearhawk 4-Place Quickbuild N22LD
            Mogollon Airpark, Overgaard AZ

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            • #7
              Originally posted by tailwind View Post
              If your not in a hurry for a carb air box you might wait a month. There may be something better coming. I have it on pretty good authority.

              Zane,

              Did you ever land on an air intake box?

              Did that "something better" ever come along??

              I'm starting to give this some thought and considering the options.

              Steve H - would you have any details/pics of your O-540 Van's FAB?? How much extra work involved?

              Appreciate any and all help? I'm at a high angle of attack on the firewall forward learning curve!
              Thanks too much,
              John Bickham

              Los Lunas, NM Mid Valley Airpark E98
              BH Plans #1117
              Avipro wings/Scratch
              http://www.mykitlog.com/users/index....er&project=882

              Comment


              • #8
                Hi John,

                Regarding the Van's FAB:

                I am traveling on business this week and don't have any detailed pics - I could take some this weekend when I get back. I don't think it adds much work, probably less than trying to fit a bracket type air filter.

                The FAB box with the air filter bolts right up to the carb - no changes at all were required there. I used the largest scoop from Van's for the bottom cowl. That took a bit of work to get it to match up just right. I started by rough cutting a hold in the bottom cowl the minimum size I could to allow the carb and FAB box to fit through. Then worked on trimming and fitting the scoop to the cowl to get it lined up. Once roughly in place I drilled and clecoed and then did a couple rounds of fiberglass work to finalize the fit. Once happy with that I did a final trim of the cowl bottom and riveted and glassed the scoop to the cowl.

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                • John Bickham
                  John Bickham commented
                  Editing a comment
                  Thanks Steve.
                  I'll be based at a dirt/grass strip. Only visit pavement for fuel, food, or restroom. Plan to do a lot of dusty, desert flying also. Got some friends in Jordan Valley, just east of the Steen's, that I visit as often as I can. Not too far from you? The fact that the Van's FAB is filtered carb heat may be better for that investment up front. I'm still trying to understand the carb heat valve on the Van's unit. It looks like it is flow on demand instead of the traditional continuous diverted bypass flow?

                  Does the glassed scoop make removal of the bottom cowl for maintenance/inspection much more difficult?

                  Appreciate the help.

              • #9
                Hi John,

                The carb heat is a simple flapper valve near the front of the FAB unit. When it is open (no carb heat), there are some gaps around the edges that allow the air to flow by. When carb heat is applied, you get the warm air - although those gaps are still there so it isn't perfect. All air (normal or with carb heat) is filtered. There is provision for an emergency alternate air that is not filtered for use in case of filter blockage.

                The glassed scoop is designed to have about 1/2" of clearance to the FAB box that is closed with baffle material. This allows for relative movement between the engine and cowling as well as removal of the bottom cowl.

                If you can find an RV near you to look at you can get a pretty good idea how it works. I actually was pretty surprised that the scoop fit relatively close on the Bearhawk cowl without a ton of fiberglass work.

                Jordan valley isn't too far away - about 250 miles as the crow flies. Of course you are welcome to drop by! Come summertime I plan a couple trips to Idaho backcountry - likely stop at the Alford desert near the Steens as well. Nice country!

                Steve

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                • #10
                  At the Alvord, Sept. 2014. IMG_0458.JPG

                  Hoping to get back soon.
                  Thanks too much,
                  John Bickham

                  Los Lunas, NM Mid Valley Airpark E98
                  BH Plans #1117
                  Avipro wings/Scratch
                  http://www.mykitlog.com/users/index....er&project=882

                  Comment


                  • #11
                    Originally posted by 22LD View Post
                    Has anyone used the Sam James filter kit for an IO-540 that uses a K&N filter? Here is a link to his web page. http://www.jamesaircraft.com/?page_id=43
                    Yes I have used that design, except I made one myself rather than buying one from James Aircraft. Fibreglass is so easy to work with, plus I had some unique design requirements, so I just did it myself.

                    I went the SCEET tube route, for the connection between the cowl and the air box. It's amazing how much the cowl moves in flight, not vibration, but lifting because of aerodynamic pressure both internal and external. My cowl lifts about 1/2" at the front, in flight.

                    For that reason, I don't think I like the engine-touches-cowl idea for sealing a filter, just one more way to pass vibration into the fuselage.

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                    • #12
                      Still looking for a basic airbox solution. The James/Battson style is attractive because of the K&N filters, as is the Vans I guess. I'm not so worried about having a clean cowling as I am just a solid solution. I'm fuel injected so don't need the carb heat flap.

                      Anyone find anything as yet unmentioned?

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                      • #13
                        I've ordered the ACS airbox version for the O-540, but the quality is very disappointing for $300. The box is made of thin steel, and looks amateurishly pounded together. The flush rivets are not flush, and not set correctly. I'm hoping to find a better aluminum or steel alternative so that I can return this version. I may just make my own with a rear-facing carb heat, but it's quite a few parts and a lot of work.

                        Tailwind, did your good authority tip pan out?

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