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Thread: Cool App! Volumetric Efficiency Calculator

  1. #1
    Join Date
    Jul 2005

    Cool App! Volumetric Efficiency Calculator

    Sweet! I got my webspace figured out. Now I can share some of my goodies...

    For starters, here's a link to a kewl lil program that calculates the Volumetric Efficiency of your engine at any revs. Notice how your peak VE will occour at max torque. It's taken me years of thinking to work out what torque actually is. In it's most basic form, it's how much force is being applied to the top of a piston after combustion. And so that's why max torque, and max VE go hand in hand.....

    As power is torque x revs, then you can see the reason an engine's power starts to plato is due to the engine no longer being able to fill the cylinders to their capacity. Your VE at max power will be lower than at max torque!

    Anyways, here's the link:-

    You will notice that good n/a engines can go as high as 105-110% VE. That's using gas flow to actually pass the 100% figure. Kinda like free forced induction....

    If you know how much power your engine has, and want to know what the torque is, the formula is this:- (HP x 5252)/RPM=torque (lbs/ft I think!) Use for any conversions....
    Will race for food!

  2. #2
    Join Date
    Jun 2003
    Nice program except it is Cubic inches...get Convert..greta little program:

    Awesome free tool to have on the desktop,

    (you ashould have alook for Desktop Dyno....that is impressive as well.)

    The math to work it out Volumetric effiency is the actual Volume the unit pumps Divided by the theoretical volume it could pump.

    It is considered to be the degree of the "inability to pump"

    ie: if the engine pumps 80% of its total theoretical total..then it is missing %20 of its displacement per revoloution.

    Im interested in this stuff as well....Especially Volumetric effiencys and the other math you can use to select blowers to give you yoru desiered Power.
    1984 E28 528i 5spd Manual
    1979 E21 323i 3spd Auto (rebuilding)
    Want E28 info:

  3. #3
    Join Date
    Jun 2003
    Quote Originally Posted by ACE-E28
    Nice program except it is Cubic inches...
    There is a "metric" checkbox.

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