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Fitting K&N air filters

Discussion in '365 GT4 2+2/400/412' started by SouthJersey400i, Dec 19, 2011.

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  1. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,679
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    #1 SouthJersey400i, Dec 19, 2011
    I went and bought a pair of K&N Filters. Previous posts indicated that K&N 33-2570 was the correct filter and looking at the pictures it seemed correct. Apparently the VW K-70 (whatever that is) is the normal user but it also fits some Porsche applications in the early '80's that probably used same fuel injection system. In a post a couple of years ago our regular poster Bruce (blkprlz) said that this filter fits the air box.

    So Saturday was the day to make a the swap. And by Sunday they were both in! They are not a direct fit. The rubber surrounding the filter on the K&N is at least a half inch think and slightly larger in both length and width. There is no issue with getting a good seal on the clean side of the filter but fitting it into the air box is the trick. The UFI filters set right in the sheet metal housing. I got the right side in (sort of) by just trimming a little of the rubber where the bolts need to fit adjacent to the filter. It was in but not elegant. It definitely needs longer bolts since the sealing surface is 1/2" thick. On the left side, after sleeping on it, I did a lot more trimming of the rubber and it when in a lot better. It set down in the air plenum. I will wait for a good excuse to redo the right side.

    Anyone have similar experience? I am a fan of K&N from several aspects but this was tougher air filter change than normal.

    Ken
     
  2. Ashman

    Ashman Three Time F1 World Champ
    Owner Silver Subscribed

    Sep 5, 2002
    33,264
    MA
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    John
    #2 Ashman, Dec 20, 2011
    I'll be interested to hear if you think that the difference is noticeable.

    My impression is that K&N filters allow easier breathing but at the cost of less filtering. Not a problem with a race engine that gets rebuilt often but I'm not so sure that I want that in a road car that I plan to keep for many years and miles.
     
  3. Ak Jim

    Ak Jim F1 Veteran
    Owner Rossa Subscribed

    Dec 23, 2007
    9,626
    North Pole AK
    #3 Ak Jim, Dec 20, 2011
    I got a K&N for my 5.0 Mustang. After 10k miles I checked it. The intake down stream of the filter had a light dusting of dirt. There was none prior to putting in the K&N. I noticed the same thing on my other vehicle with a K&N. I promptly threw them both away. Now I do live in a very dusty place (glacial silt) so the results would probably be better in other locations.
     
  4. blkprlz

    blkprlz Formula 3

    Mar 24, 2007
    2,169
    Tampa bay
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    Bruce
    #4 blkprlz, Dec 21, 2011
    For the life of me, I don't remember where I got the cross-ref., I believe it was from stated dimensions of each.

    Good point.

    That's not good!
     
  5. Flinch

    Flinch Formula Junior

    Nov 15, 2009
    302
    Holland and Sweden
    Full Name:
    Peter El Cheapo
    #5 Flinch, Dec 22, 2011
    Are the mentioned filters the same as these on this C4?

    [ame]http://www.youtube.com/watch?v=B6ZrGnnfQiw[/ame]

    These filters are pretty common in the vintage rally scene and the same as for the very populair 40DCOEs.
     
  6. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,679
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    #6 SouthJersey400i, Dec 30, 2011
    Flinch
    No these fit in the rectangular 400i box. The problem is they are thicker than the UFI filters and hang out the side a bit.

    I have a couple of cars with over 200,000 miles on them with K&N filters. I believe if properly oiled they filter quite well.
    Ken
     

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