That is only for the trailing plug Skip.
   There must have been something else going on with the Rotamax.

   Paul Lamar


  Thanks Skip...no doubt about the factor of the apex seal going by the
  spark
  plugs.I remember at some point one of the Mazda factory guys in the early
  1990's telling us they dealt with this factor when they did the three
  sparkplug modification for the four rotor LeMans project.They were using
  castings with an additional sparkplug above the two original sparkplugs
 to
  address the highly quenched trailing end and its poor flame propagation,
  they made the plug hole as small as possible.It demonstrably worked to
  address fuel consumption byburning some of the fuel that was before
 simply
  going out the exhaust pipe.

  But having said that, the leakage was clearly
  evident because while it actually improved fuel consumption, the
  volumetric
  efficiency of the engine dropped according to the Mazda folks.About the
  simplest way they addressed the high-to-low pressure area flow was to
 keep
  the plug hole as small as possible.For our application of the engine to
  sustained high power settings involved in aircraft use, at this point in
  development and using proven technologies, it seems the three sparkplug
  approach with this small hole would work well to substantively address
 the
  issue of this highly inefficient and quenched area in the combustion
  chamber.

  But Mazda is driven by the automotive production market and it is
  clear they ran the numbers and more cost-effective to develop the two
  sparkplug side port RX-8 to reduce the overlap and improve BSFC for road
  cars.Just wonder whether deep in the bowels of Hiroshima whether a group
  of people have, or arepresently working to save this little engine by
  experimenting with more than one option, includingUncle Paul's turbo
  compound ideas.If not, it is because their hands are tied financially by
  short term cash flow and profitabilitythreatening car companies.The
  Mazda organization has some amazing, smart folks who remain inspired by
  their rotary "father", then later Mazda Chairman Yamamoto.It seems they
  must have already, or are currently exploring the TC option to see what
 it
  could hold for this little engine by putting to work that unusually high
  amount of energy going out the exhaust pipe.

  Meanwhile, absent any major
  changes in design, we know a three sparkplug approach works to improve
 the
  burn and improve fuel mileage.Yasuo Tatsutomi told Yoshinori Honiden they
  had to reduce fuel consumption 10-15% to win LeMans with an rpm band that
  could range from 6,000-9,000.To do that with a standard, homogenous
 charge
  engine is like climbing Mt. Everest. They simply could not have done it
  without those rotor housings.Even with them, the LeMans drivers had
 strict
  orders from Yoshinori Honiden to lift and early/coast at the end of the
  straight and soft pedal through the corners.The primary goal was fuel
  savings but it was also easier on the engine heat flux.In this respect
  they even went from black to silver paint on the upper engine cowlto
  address temperature issues.

  The previous year the ceramic exfoliated inside
  the engines. Aircraft race duty cyle is harder--no lifting at the end of
  the straight stretch and going into corners-- and we are attempting to do
  that using what are basically warmed over, off-the-shelf production parts
  for grocery getters.That is a serious challange no matter how we slice
 it.
  But in the words of Nobuhiro Yamamoto (he headed up the third gen RX-7
  engine development),after the LeMans effort,"We can no longer say we
  share major components between the production and racing rotaries.But we
  are still a very close bunch--the rotary people!"A rotary brother indeed.

  -
  Steve Beckham

 Steve,
 I was wondering if it might not be easier to go the opposite way and put a
 sufficient depth recess in the rotor ( perhaps a high compression rotor),
 in
 the squish area leading to the larger rotor depression. It may not have to
 be very deep or wide, perhaps a couple of mm deep and 1" wide.
 I don't know how that would affect the compression and power, but it might
 solve the unburned fuel issue.
 Just a suggestion.
 George (down under)

 It has been tried George. You saw it here a few months or maybe years
 ago. It may have been on the Norton before the Midwest and now
 well before Diamond took over.

 Paul Lamar


Yes Paul, those approaches have been tried since the early development
days...at Mazda clear back to when Kenichi Yamamoto was a development
engineer.  They tried many, many rotor recess combinations trying to deal
with this phenomenon.  Ditto Curtis Wright and assuming the Germans as well.
If anybody could have broken the code to addressing this issue related to
rotating combustion chambers a great percentage of cars today would have
rotary engines.

Steve Beckham

I may have a few suggestions that have not been tried myself :)
The piston pump version is Dualsoupape.
http://www.pilotfriend.com/aero_engines/aero_soupape.htm

Paul Lamar