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REVVING LIMIT???

Discussion in 'Engine Building' started by vetch22, Aug 9, 2003.

  1. vetch22

    vetch22 Junior Member

    wuz up crew.. hey i have a qucik question what would i need to change in the upper side of my engine ie the head to safely revv to 10-11k with out any probs and around how much am i looking at for a decent setup thanks
  2. IDMaxGuy

    IDMaxGuy Senior Member

    um... sell ur honda and buy a bike.
  3. Loco Honkey

    Loco Honkey Banned

    OK, and how about a real answer now...

    First off, you'd need to lighten the valvetrain using lighter valves (ss thinner stemmed valves), titanium keepers and retainers. Stiffer valve springs will help too. The bottom end would have to be blueprinted, the crank micropolished and knife edged, a windage tray installed, and would need forged pistons and rods and heavy duty rod and crank bearing studs.

    Now, that all sounds easy, and it is, for the most part. But what we run into when building an engine to spin 11K RPM isn't so much a physical limitation as it is an efficiency limitation.

    We're talking about naturally aspirated four cylinders here, just to clarify.

    To flow enough air at that high an RPM to make power, you need huge ports and monster valve lift, duration, and overlap. This is all well and good, but the engine won't make any power down low (like, below 6000 RPM if you're building it for 11K RPM), and won't idle at a reasonable RPM. It may not even idle below 2000 RPM.

    This is all well and good for a hardcore balls out no apologies race motor, but for something that you'll drive once in a while without wearing Nomex, it's more impractical than you can imagine. You'd be beat by cars with half the power. V8s would laugh at your gas milage. And you'd be rebuilding the motor at about the interval that you change your oil now.

    Rather than asking us what it'd take to rev to 11K, you need to ask yourself what your goals are with the car. And be realistic. New developments happen each day, but you can't cheat physics.

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