Interference Engines ?

Discussion in 'General Motoring' started by Bob, Sep 25, 2010.

  1. Bob

    Bob Guest


    What's an "interference engine" ?

    Saw the term on all the posts re timing belts.

    Bob, Sep 25, 2010
  2. Bob

    Tegger Guest

    A quick Google reveals...

    In a nutshell, pistons and valves like to dance by themselves. If one
    steps on the other's toes, expensive chaos ensues.

    Some manufacturers design the valves and pistons to have their own private
    dance floor. Honda makes those parts /share/ the dance floor (or at least
    parts of it), meaning that something has to tell the first dancer when
    to leave so the second may perform without interfering with the first.
    That's the job of the timing chain or belt.

    Why does Honda do this? Apparently the engine works better when the
    valves and pistons share a dance floor.
    Tegger, Sep 25, 2010
  3. Bob

    Erik Guest

    Check this as well.

    Erik, Sep 25, 2010
  4. Bob

    Jim Yanik Guest

    or simply put,if the timing belt breaks,the valve train stops turning,and
    valves may be left in a position where a piston can strike a valve,damaging
    both the valve and piston.

    making a very expensive repair.

    Jim Yanik
    dot com
    Jim Yanik, Sep 25, 2010
  5. Bob

    Dillon Pyron Guest

    And they do this dance twice per cycle.
    If the intake cycle starts to open while the exhaust valve is still
    open (with electronic port injectors helping out) fresh air improves
    the exhaust.

    Some of the high, high end makes have experimented with electronic or
    pnuematic "cams" to improve this depending on piston speed. Think F1.
    Think a team that quit at the end of last year.

    If it were an 11 to 1 race car, I could understand this concept, but
    not a street car.

    In fact, many of the high compression pistions I've seen are sculpted.
    To accomadate the valves, that usually have much higher and longer

    - dillon I am not invalid

    Toby (Tri-Umph That's the Sweet Truth)
    March 1998 - June 2010
    What a dog. What a dog!
    Dillon Pyron, Sep 28, 2010
  6. Bob

    Dillon Pyron Guest

    Yeah, our 84 Escort GT did this with a little over 3000 miles on it.
    It took almost a year and calls from our lawyer to Ford's general
    counsle to get paid for the repair, the tow, the legal fees and
    "general inconvenice". We wanted a recall, they insisted on a TSB.
    And we got an agreement on no NDA after 6 yeas.


    - dillon I am not invalid

    Toby (Tri-Umph That's the Sweet Truth)
    March 1998 - June 2010
    What a dog. What a dog!
    Dillon Pyron, Sep 28, 2010
  7. Bob

    jim beam Guest

    that's called "overlapping" valve timing, and it's been used on overhead
    cam car engines since about 1923. it's got nothing to do with "fresh
    air" in the exhaust but everything to do with scavenging the contents of
    the cylinder and improving volumetric efficiency.

    not exactly. all variable valve timing systems are mechanical with
    electronic control. "piston speed" is also grabbing the wrong end of
    the stick - it's all about the overlap needed to scavenge successfully.

    no, think honda v-tec. think toyota, think bmw, think fiat, etc. the
    pneumatic systems used in f1 are simply reverberation-free valve return
    springs and have nothing to do with variable valve timing - something f1
    typically doesn't bother with since the engine is used in a narrow rev
    range where variable valve timing is irrelevant.

    that's because of the valve's lift and duration. variable valve timing
    has nothing to do with it.
    jim beam, Sep 28, 2010
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