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Need help in calculating Engine Air Flow and Specs Explanation

  1. May 15, 2016 #1
    hello everyone,
    i hope you're doing well, i am new to this forum so i am not sure if this is the right place for my question
    what i am doing is trying to calculate the air flow needed for intake of an RC engine Zenoah G320RC
    in the attachment files, it's a pdf for the info about the Standard Zenoah G320RC engine, but the one i am using is a tuned version of that one with a 30% to 40% more power, but will use the standard specs for the moment to learn, so i have been searching for calculating the air flow, the formula needs VE % but it doesn't seems to be mentioned in the specs file so i need your help to figure out how to calculate the Air Flow needed please ?

    and i would like to know if a bigger air intake surface would have negative effect or it would be just more structural material which should be eliminated for weight purpose ?

    thanks in advance to everyone

    Attached Files:

    Last edited: May 15, 2016
  2. jcsd
  3. May 15, 2016 #2

    jack action

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    VE is calculated by dividing the actual measured airflow by the theoretical airflow that can go in the engine (displacement X rpm). So you either need to actually measure the airflow of the engine or used a complex engine cycle simulator to do the calculations. There are no easier way.

    The intake design (cross-area and length) can affect airflow by taking advantage of the pressure waves created by the engine's cycle. Although, on the intake side of a 2-stroke engine, it is not of a big effect because the crankcase is part of the intake system; So it shouldn't make a big difference to alter your intake design (as long as you don't restrict the flow).
  4. May 15, 2016 #3
    hello Jack and thank you for your reply, there is no way to measure that or in a software, so you saying that if my air intake surface is bigger it will do harm if it was a 4 stroke ? my engine is 2 stroke
  5. May 15, 2016 #4

    jack action

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    I don't know if it will do harm, but it can affect the airflow. A given cross-section area and length of the intake system perform better at a given rpm. If that rpm doesn't coincide with the rpm range you expect from your engine, then it can do harm.
  6. May 16, 2016 #5
    ow ! ok thank you Jack for the info :)
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