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    • CommentAuthorkamran
    • CommentTimeOct 10th 2010
    Hello all,
    I'm thinking to use a sliding exhaust valve instead of poppet valve on a slow running, low compression engine.
    Do you think this is something that makes sense? If so what is a disadvantage of such a valve?
    I know it will affect the compression ratio, but like to know if it works and not going to be an issue that I'm not aware of it.

    Here is a diagram of what I'm talking about
    • CommentAuthorjay rich
    • CommentTimeOct 14th 2010
    hi kam try a rotary valve i have goofed around with this idea and found out it will work but you must keep a tight tollerence
    the advantge is higher rpm also less strane on the engine ....jay
    Is the engine a two stroke or a four stroke.
    How much pressure will be needed to run the engine. Compression ratio of 5:1 - 6:1.

    I guess the problem may be leakage, when you need compression to help ignite the gases, like in a automotive engine, you are better of with a poppet valve.
    You can use the rotary valve, it is easier to design it in a 2 stroke, since it goes in sync with the crankshaft and does not need a separate mechanism ( gears or belts) to drive it.
    If you have to do some timing driving mechanism, I would stick to the poppet valve, they are easier to time and adjust, unless you are having some space issues in the head design.
    There are some very simple designs used in the hit and miss engines which may fit your need.
    Not familiar with the used of slide valves outside of steam engines or two stroke engines.