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Stock 308 Air Filter power loss on dyno

Discussion in 'Technical Q&A' started by snj5, Dec 11, 2003.

  1. snj5

    snj5 F1 World Champ

    Feb 22, 2003
    10,213
    San Antonio
    Full Name:
    Russ Turner
    Just a copy from the other thread from my time on the dyno:

    Fun fact: the difference between paper airfilter/airbox and just air box was 8 horsepower !!!! Unlike the Forza article on the 308 comparison, when I took the airbox off I gained 14 horsepower over baseline!!!!! Of course, no ram effect was in play on the dyno, but interesting numbers, don't you think? So where do I get a 308 K&N?

    best
    rt
     
  2. Mike C

    Mike C F1 Veteran
    Owner Lifetime Rossa

    Aug 3, 2002
    6,061
    Southeast USA
    Full Name:
    Mike Charness
    Get the correct part number from
    www.knfilters.com
    and then your local AutoZone or other local parts store can order it for you. Or order it over the net.
     
  3. mk e

    mk e F1 World Champ

    Oct 31, 2003
    11,384
    The twilight zone
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    The Butcher
    Russ,
    Your engine is quite rich, removing the filter would tend to lean it and is probably why you saw the hp increase.
     
  4. snj5

    snj5 F1 World Champ

    Feb 22, 2003
    10,213
    San Antonio
    Full Name:
    Russ Turner
    Mike
    You know, you're right. I thought about that as well just now and I went back and checked - there was about a max .9 point difference in A/F (11 and 11.9). Would that affect other cars' mixture similarly?
     
  5. Mike328

    Mike328 F1 Rookie

    Oct 19, 2002
    2,655
    Boulder, CO
    Full Name:
    Mike
    I just ordered a K&N here: http://www.performanceintl.com/


    $50. E-2930 is confirmed to be the p/n for carb 308s.

    Reference: http://www.ferrariclub.com/faq/knfilter.html


    Item Order Summary:
    ------------------------
    E-2930 - 1978 FERRARI 308 GTS - K & N: REPLACEMENT AIR FILTER
    $50.22 x 1 = $50.22 (Shipping: $0.00)


    ========================
    Subtotal: $50.22
    Shipping Cost: $0.00

    ========================
    TOTAL: $50.22
    ========================
     
  6. mk e

    mk e F1 World Champ

    Oct 31, 2003
    11,384
    The twilight zone
    Full Name:
    The Butcher
    Russ,
    Yes, it would affect all engines the same. In fact dynojet (at least on motorcycles) teaches the dyno tech to make a run then pull the air filter. If hp goes up it's rich, if it falls it's lean. it should only change by a fraction of a % if the mixture is correct, assuming the filter is close to the right size...clearly there would be exeptions, but that's normally how it works.
     
  7. 308SYSTEMS

    308SYSTEMS Karting
    Silver Subscribed

    Dec 16, 2003
    51
    FYI - I ran a back to back dyno test of the K&N vs stock FRAM filter on my 85 308. The K&N actually DECREASED the HP by approx 2hp.

    Mark Lueker
     
  8. Mike C

    Mike C F1 Veteran
    Owner Lifetime Rossa

    Aug 3, 2002
    6,061
    Southeast USA
    Full Name:
    Mike Charness
    Mark L, I wonder why that would be the case on FI engine...? I guess one might still need to adjust the mixture.
     
  9. pma1010

    pma1010 F1 Rookie
    Silver Subscribed

    Jul 21, 2002
    2,556
    Chicago
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    Philip
    Russ
    Your data quantifies what we've known: getting the mixture optimized is valuable. I am curious what power increase you see from changed jetting/getting the AF closer to 13:1.
    Philip
     

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