... what about my question
    on the max compression ratio for a wankle rotary without the combustion
    chamber depression ? Can it reach 16:1 ??
    -dave

    Yes but then the fire goes out.

    Paul Lamar


    Paul and Dave,

    as mentioned earlier I have been working as development
     engineer for
    Wankel Supertec for two years. Target was the development of a spark
    ignited Wankel rotary engine, running on Diesel or Kerosene. I have
    actually built and re-built approx. 20 Singles and one Twin rotor engine
    (see attachment) in those days. The actual compression ratio was in the
    order of 14:1 including a cut-out in the rotor flanks. Without those
    cut-outs the theoretical max. compression ratio would actually have been
    16:1!

    The engine ran on Diesel without the support of the spark plugs at
    nearly all loads and speeds except tick-over! But admittedly it ran a
    lot smoother with the ignition being switched on. We even managed to get
    it firing up on diesel right from a cold start without the addition of
    petrol as we used to do at MWE!

    WankelSuperTec relocated all of their development work to Cottbus
    University last year - and to Korea, see: http://www.lmlkorea.com/

    The prices of Diesel
     and unleaded petrol in Germany are very much the
    same these days as the government has increased the tax on Diesel quite
    considerably this year. So the major advantage of the Diesel Rotary will
    be in areas where there won't be any more petrol available...

    Regards

    Martin

Dave,

You can make almost anything work like a diesel with any compression
ratio and a turbo but the question is how well will it work. Using the
stock R/e ratio of 7 will not allow you to make the best possible
scenario for a diesel in terms in efficiency,emissions and such. Wankel
engines NEED a certain amount of a cutout in order for the combustion to
carry out effectively/fully. So any theoretical compression ratio is
usually reduced by about 4 to 6 points based on the shapes Mazda has
used up to this point. If this is a consistent trend, like most things
in a wankel engine in terms of scaling, you would need something that
gets you a 22:1 comp. ratio minus this 4 to 6 points due to the cutout
which would put you in the R/e ratio of about 9. This R/e ratio, also
known as K, completely controls the shape of the engine. That being said
a wankel diesel would end up being bigger than the current K value of 7
the current engine has. So the answer is yes it can be done with a stock
13b but why bother because it will suck. I am sure there are other
factors but the main one is this.

Rob Woods