The intake period is 270 degrees of e-shaft rotation as are all other
   strokes. In a p-port there is a depression in the rotor face that
   connects the intake port with the exhaust port. Surprisingly the
   pressure in the intake is higher than the pressure in the exhaust.
   Therefor air flow, if any, goes from intake to exhaust in theory.
   However air has mass, friction, adhesion and inertia. So what
   goes where and how much is arguable.

   Here is a Racing Beat 3 rotor P-port turbo making 900 HP as I recall.
   Some of the end housing are aluminum.
   Note the size of the turbo charger :) One would think the
injectors,   being on the plenum side of the long intake runners,
 would lose   fuel to the exhaust. Jim Medere told me that was not
the case.   In fact the BSFC was slightly better with the injectors
at the start   of the runners. I can't wait to see what happens when
Dave Lemon   builds a welded p-port with a slide throttle RX8
engine. Should be   around 600 HP or more instead of only 420 HP :)

   As I recall the 3rd gen RX7 stock body land speed record at 268
MPH was   set with a 3 rotor, 3 turbo side port engine making only
about 750 HP.   It had an ice water inter-cooler as I recall.

   BTW a picture taken from my C182 made the centerfold of Pop Sci
   mag the year of the flood at Bonneville. That was the first year the
   recording holding R.B. 3rd gen 3 rotor RX7 showed up.

   http://www.youtube.com/user/PaulLamar2#p/u/11/JUf_aWVVl7o

   With our man on here Csaba  Csere narrating no less.
   I got my 2 cents in at the end.

   Paul Lamar

   I have to wonder about the concern everyone has been showing about
   overlap.
   There is considerable overlap in any piston engine. The exhaust
and   intake   valves are both open on even a low output piston
engine. There is even   more   overlap in a high output engine. I
haven't timed any cams lately but iirc   the cams have about 30
degrees of overlap. Due to the velocity and   mass of   the intake
charge some will often flow out the exhaust. Since the rotary
 doesn't have valves in the way timing is very important, but a lot
of the   overlap events are similar.   Bill Jepson

  My concern was in the volume of air that passed from the intake through
  the chamber and out the exhaust, and the amount of fuel in that
flow. It  appeared to me that if the injector timing could be
manipulated so that  at cruise power the air passing through to the
exhaust carried the least  possible amount of fuel, better
efficiency would result.  It may be that the volume lost is
inconsequential, or that the timing  cannot improve the loss - but
since lean cruise fuel flow is less than  half max power flow and
therefore injectors are on less than half the  time, it seems
reasonable that some injection timings will be better  than others.
One reason direct injection engines can get better fuel mileage is that
  they lose no fuel out the exhaust during valve overlap.  It is
also one  reason that port injection engines can get better mileage
than those  with throttle -body injection.  I ask the group's
forgiveness for my intrusions - I know I have a gift  for causing
unintentional irritation.

  Victor Roberts

  You have a valid point there Victor. When the fuel is injected
relative to  top dead center could be important.

  So far we have no control over that as Tracy does not publish the source
  code of his system. We think he injects fuel once a rev. I'll find
out  as soon as I get my engine instrumented with a data aq system.

  Paul Lamar

Paul it is probably a good idea to inject into the chamber after the
port closes to prevent charge dilution. I talked to Orbital about direct
injection, and their system was banned by some racing organizations
as being a mild form of supercharging. It wouldn't matter to us of
course. You have used the oil injection hole for a good vacuum
source, and it seems a good one. Someone in the group suggested it
as an injection port and it would probably be good for that as well.
Bill Jepson



If you can make a welded p-port housing, it should be easy to use the same
system to put a direct injector where you want or can.

Dale Davies

The problem is compression is lost across the hole due to leakage
over the apex seal. It helps to keep the hole as small as possible.

Paul Lamar