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Airfilter housing for CF Airbox

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  • Airfilter housing for CF Airbox

    Over the last few days I've been working on an airfilter solution using a CF airbox. The reason for attempting something different for the airfilter setup is that I wanted to minimize powerloss from the filter as much as possible... Taking Jefrem's advice, I attempted to duplicate the design he came up with from his dyno testing with his motor. Instead of placing the airfilter directly in the collector, I installed a stock style K&N filter next to the radiator on the front side of the radiator support, and fabricated an aluminum housing to direct the airflow into the collector and form and airtight seal. Again, this is Jefrem's idea not mine, but here is what I came up with:

    http://www.bayareamotorsport.com/~jj...ilter_Housing/

    I speculate a larger chamber behind the airfilter is an improvement in resonance tuning and there is more "space" to resolve air turbulence out of the filter before the air stream narrows down in the collector and enters the airbox chamber (where the tuning is more critical). There is also more airfilter frontal area this way rather than cutting down a filter to fit into the slightly more narrow collector inlet. I'm heading to the dyno tomorrow, If I have enough time I'll try this setup and then with the filter directly in front of the collector...
    Jeff J.
    1990 E30 M3

  • #2
    What did Jefrem find with his dyno testing of setups?

    T

    Comment


    • #3
      Originally posted by HANDBLT
      What did Jefrem find with his dyno testing of setups?

      T
      Alot of interesting things :-). One of the more important conclusions was that the lower collector and snorkel need to be in place, at the angle for which they were developed, and that filtration should take place upstream of them.

      The airbox we made is very similar in dimension/design to Jeff's, and that was the best solution we found as far as WOT HP.
      Jefrem Iwaniw

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      • #4
        Looks nice! It will be interesting to see the dyno figures when you get them. Would making a lip on the inner edge (closest to the fan)of the filter housing make the incoming air less turbulent? It might reduce any fan turbulence.

        Comment


        • #5
          Originally posted by jefrem
          Alot of interesting things :-). One of the more important conclusions was that the lower collector and snorkel need to be in place, at the angle for which they were developed, and that filtration should take place upstream of them.

          The airbox we made is very similar in dimension/design to Jeff's, and that was the best solution we found as far as WOT HP.
          Can you do a write up sometime so we can get the full jist of the testing, if it's not confidential of course.

          T

          Comment


          • #6
            I really like the brake fluid bracket!!

            It looks way complicated for a air filter. How long does it take to change it out?

            I see what you are saying, but honestly how much MORE hp over a in collector filter does it make? 2-3hp?

            How good can the seal be between the collector and frame, then to the new air box and filter? What did you due about the top where it narrows?

            The angle does that get a more direct flow from the air flowing threw the front grills?

            Do not click
            At least it's German

            Comment


            • #7
              Wow, that looks great! Did you use any type of gasket, or possibly a sealer between the filter housing and the frame to prevent leaks? Although, any leaks would probably be minimal if you built it precise enough.
              Bryan K.
              Texas A&M Formula SAE

              Comment


              • #8
                The filter box looks kinda rough right now, I will probably go back and make it look more refined later when I have the time. Most importantly it does not leak and is completely airtight. Where it presses up against the frame I used foam weather strip to press against to form the seal. In addition, I used tape around the seams but I dont think its really necessary if you cut the edges tight enough. I rivited it all togther then used aluminum sealant around the edges. It mounts through the frame and then the collector via 6 small bolts. The only modification I did to the car was drill 3 new small holes to fit the bolts through.

                Changing the filter requires pulling off the front bumper to get it out. I just undo the two nuts holding it down and it slides out. I will probably switch to an amsoil filter b/c its thinner and it filters better than the K&N. The K&N touches the fan and frame a bit which is why its bowed in on the sides in the pic..

                Air filtration has a big impact on performance! I think people kindof neglect this part, but then spend getting every last HP from the motor elsewhere. Its no fun losing power to a filter when a different setup might flow better.

                Here is the thread from Jefrem on air filters, he can probably offer more actual facts on the subject:

                http://www.s14.net/forums/showthread...m&pagenumber=1

                As far as flow into the filter, having it angled like this might scavenge air that flows off the surface of the radiator. That area infront of the radiator is a high pressure "collector" in effect intended to force and direct air into the radiator. Having it angled rather than straight might collect more of this air from this high pressure zone, I dont know. Most importantly, the filtration takes place before the critical tuning area of the collector.

                The brake fluid bracket was easy! Just get a long alumihum piece and bend it into place, and anchor it to the two holes where the wire harness is. I'll have to slightly cut the cover some to fit over where it exits but meh.. It keeps it out of the way of the large CF airbox and it still clears the hood.
                Jeff J.
                1990 E30 M3

                Comment


                • #9
                  I used a similar alum bracket for my brake fluid resevoir.
                  but it sits on the shock tower next to the power steering resevoir.

                  nice airfilter setup Jeff. thats also how I recommend doing it.
                  in fact we did it similar, just no such an angle.

                  actually, im thinking of making a siphon for it
                  from the BMW kidney. This is an extra piece you can take
                  out at will.

                  John
                  Last edited by John; 01-06-2004, 12:14 PM.

                  Comment


                  • #10
                    OK couple of things.

                    25hp? Really? What filter was used in the end?
                    In what part of the RPM band was the gain?
                    Any tq gains, where?
                    Any low RPM, part throttle gains?

                    This is on a monster 2.5 right?

                    T

                    Comment


                    • #11
                      This was on Jefrems motor. IOW his race car.

                      25 hp is a lot, not sure what Jefrem did there perhaps
                      he can enlighten us.

                      Perhaps he got a case of heat soak? doing multiple dyno runs
                      in succession? Choke off the airbox, and it does not surprise
                      to be down on power.

                      John

                      Comment


                      • #12
                        Originally posted by John
                        This was on Jefrems motor. IOW his race car.

                        25 hp is a lot, not sure what Jefrem did there perhaps
                        he can enlighten us.

                        Perhaps he got a case of heat soak? doing multiple dyno runs
                        in succession? Choke off the airbox, and it does not surprise
                        to be down on power.

                        John
                        I was skeptical too! This was back-to-back. The 20-25 HP difference was with no filters. Did it twice just to make sure there wasn't something weird going on. It was quite compelling.
                        Jefrem Iwaniw

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                        • #13
                          John,

                          I was under the impression you would develop a carbon filterbox to be used with a K&N type insert?

                          Adwo

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                          • #14
                            yes Adwo. Ill show it to you at the ring at easter,
                            with the siphon

                            John

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                            • #15
                              Maybe someone can enlighten me here....hope this is somewhat in line with the thread.

                              Does anyone have any idea what sort of top end gains there are between the stock plenum/air horns vs the carbon airboxes? This is on identical engines, both with the AFM removed.

                              The reason I ask is because it seems like the stock setup should be fairly efficient once the AFM is out of the way. I don't doubt the CF airbox makes more power, but it doesn't seem to me like it would be a huge improvement. I always assumed the DTM cars used them primarily to reduce weight.

                              I am curious because I am debating back and forth between going with the CF airbox or retaining the stock setup. Basically I kind of like the stock air filter setup, which obviously has to be dumped with a CF airbox.

                              Anyone have any data here?

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