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308QV cams

Discussion in 'Technical Q&A' started by zff, Mar 10, 2004.

  1. zff

    zff Karting

    Nov 1, 2003
    145
    Hawaii
    Full Name:
    Ken
    After reading several threads on this site and the old one, I get the impression no one ever upgrades the cams in their 308QV. Almost all of the discussions I've seen on performance cams in 308s refers to the 2v engine.

    I've read that the QV doesn't like a lot of duration* and that there isn't enough clearance with the stock pistons to go much higher on lift. So is it that QV cams produce about as much power as they can without changing pistons?

    Are performance cams worthwhile in a QV with stock pistons if the owner was willing to switch to an EFI setup? What if he wanted to stick with the K-Jet FI?

    Thanks,
    Ken

    * I'm not sure if this is something specific to the 308qv engine or if this is true of all 4v engines in general.
     
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  3. snj5

    snj5 F1 World Champ

    Feb 22, 2003
    10,213
    San Antonio
    Full Name:
    Russ Turner
    Zff
    I'm sure it's hidden in previous posts, but the challenge with the Ferrari 4v engines is the K-jetronic mechanical FI mandates mild cams without large reversion waves that would confuse the fuel distributor airmass sensor plate. If carbs or efi are fitted (not adversely affected by a bit more reversion), much more aggresive cams can be fitted.
    I hear there is some room to improve the K-jet cams, but the power increases are not worth the cost without incurring tractability problems from the K-jetronic.
    Hope this helps,
    best
    Russ
     
  4. mk e

    mk e F1 World Champ

    Oct 31, 2003
    11,538
    The twilight zone
    Full Name:
    The Butcher
    From what I understand, the QV engines don't really need any more lift because that is not the restriction, more lift does not give more flow. A little more duration will get you more hp up top, but you need to loose the stock FI junk. Also, a duation increase without a compression ratio increase will cost you power down low, say below 3000. The rule is that all the parts have to match for it to run right. The QVs are only 8.6:1 CR, pretty low. The 328s are 9.2, so they can stand a little more duration, but not much. Increasing duration shifts the peak torque and hp point up in rpm, you can safely move up to about 7500 just like the 2v cars without getting inside the engine, that alone will add 10% more power.
     
  5. pma1010

    pma1010 F1 Rookie

    Jul 21, 2002
    2,559
    Chicago
    Full Name:
    Philip
    This is probably irrelevant, but does anyone know the duration the 4V NA race cams? I thought Michelotto built several (12?) with 4V motors - might provide some clues.
     
  6. mk e

    mk e F1 World Champ

    Oct 31, 2003
    11,538
    The twilight zone
    Full Name:
    The Butcher
    It might....I think I would also have a look at the spec for the 348s, they should be about right for a street 4v
     
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