Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

4 stroke engine exhaust fed to high air flow

  1. Jul 11, 2016 #1

    So say that I have a small four stroke engine that is designed to be kept static at ground level. I then take this engine and mount it to a small air plane, feeding the engine with either still air from inside the cabin (cargo) or the outside wind. The exhaust is fed out to the wind rushing by be plane in flight.

    What happens to the performance of my 4 stroke engine? What can I do to minimize performance loss as much as possible? Should I put a venturi valve on it? I am assuming that it is not desirable to change fuel consumption or the engines power output.

    If this is a weird question then I'd appreciate some tips on what topics to google. I don't really know much about engines.
    Last edited: Jul 11, 2016
  2. jcsd
  3. Jul 11, 2016 #2


    User Avatar
    Science Advisor
    Gold Member

    An aircraft's engine performance decreases with altitude due to decreasing atmospheric density; the higher you go in the atmosphere the lower the density of the air. Because of this, there is less oxygen available for combustion.

    Atmospheric pressure variation as a function of altitude:


    A 4-stroke engine will be especially limited unless a form of forced induction is utilized such as a supercharger. See here: https://en.wikipedia.org/wiki/Supercharger#Aircraft

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted