Paul,

Published in the October 2009 issue of Automobile.

Two engine technologies- turbocharging and fuel injection- have recently
joined forces in mechanical matromony.  Spraying the fuel directly
into the combustion chambers achieves more precise mixture control,
since no droplets are left behind on the intake port walls, injecting
the fuel at 2000 or so psi versus the 50 psi common with port injection
facilitates finer atomization and more complete vaporization.  Also
the cooling effect from the fuel's change of state from liquid to vapor
enables significantly higher compression and expansion ratios.  According
to the EPA, the net improvement in efficiency attributable to
direct  injection with turbocharging is a substantial 12 %.

Who has it:BMW,Bugatti, Chevrolet,Ford, Lincoln, Mazda, Mini,
Porsche,Volkswagen.

I checked with Mazda in Missoula, MT and they never heard of it.

Gene Sandburg

I'll believe it when I see it/ Direct injection in a gasoline
engine is not  easy. They have talked about it for years. Mercedes
had direct injector  50 years ago in their race cars. Formula 1
engines would have direct  injection if it did anything and they don't.

Porsche spent big bucks on R&D and the improvement was barely noticeable.
It is also very expensive.

Paul Lamar

Paul, reguarding direct injection on aircraft engines. It would
have the same $2500 fuel pump as a diesel and likely need a
mechanical volume metering system to fire at 6000RPM. I could see it
working on a piston engine although mixture control would be
tedious. From what I have read it is necessary to mist the fuel near
the ignition source to produce a stratified charge. This allows a
leaner mixture overall for the entire charge and a faser burn with
much of it occuring near the plug in the enriched area of the
stratified charge, The rest of the volume provides additional mass
of air to heat for expansion pressure.

In the case of a
rotary running at near maximum power we need the oil mixed in the
fuel for lubrication. If the direct injection is a stratified charge
system there is almost no exposure of the side and apex seals to the
oil and without lubrication even ceramic seals  will not IMHO
survive. I know that Mazda is working on a direct injection follow
on to the RX8 series with the 3 injector oil metering system they
now use. The metering pump seems reliable to run along at 65 MPH at
reduced power with only short seconds of acceleration power  but
this is a car engine.

I would be surprised  if Mazda
ever  raced anyhing that didn't have oil mixed fuel. If the goal is
not the fuel efficiency of stratifierd charge what possible benefit
is there to direct injection.. Introducing the fuel in the  intake
runner gives a lot more time for the fule to vaporize and cool the
intake charge. I am not sure what fuel pressures are these days in
multipoint car injection, but I think 70 PSI should be close. In out
sprint car we has 220PSI at  the inlet of the barrel valve and more
than that at the injectors when the valve was turned open. These
were constant flow systems running methanol as fuel and we thought
fuel burn was good for a 750 HP engine.

We used a high system
pressure relief valve and two drip in orfices "pills" before and
after the barrel valve for idel and max power fuel metering. the
barrel valve linked to the throttle plates  controled the fuel after
idle to full power. This was by todays standards crude as a club,
 but fairbanks wasn't making integrated circuits at that time and
aircraft radios used tubes and crystals for tuning.

Now we have EFI with the possibility of changing charge density
by  timing the beginning of the pulse so that an enriched mixture is
around the plug when it fires. It would appear that a p-port rotary
with an optimized port shape and the fuel sprayed by two injectors
near the top and bottom of the port could produce a sratified chargefor
a rotary . engine running at a near constant RPM. The goals
would be to reduce swirl mixing and introduce the fuel during the
most laminar flow into the rotor chamber by adjusting the beginning
point of the fuel pulse timing.

george grimes

Hi folks,
I purchased a '09 Mazda 3 this spring. It has the MZR 2.3L DISI engine. It
comes with 4.1 final drive so revs are  about 2750 at 110Kph (68 MPH). A bit
high to my mind but goes up hills in cruise without batting an eye.
To check the direct injection, Google mazda DISI. Select
www.mazda.com/mazdaspirit/env/enginedisi3.html
Just click the red box when the install language nuisance comes up. There
is an animation of the combustion. Select 2.0L DISI. There is also one about
the Millar cycle which I believe Crower played with 25 years ago. Did not
work as well as without VVT.
Suppose you injected a small amount of fuel into the area of the spark plug,
with a very lean mixture in the main combustion chamber of a rotary. Think
diesel pre-combustion chamber. The rich mixture at the spark plug would
ignite when the rest is too lean to ignite. The flame once started would
then propegate to the lean mixture. Combine with turbo compound to regain
lost power to the lean burn. Just a thought.

Dale Davies

Does it get better gas mileage than a Honda or Toyota?

CW, John Deere and RPI fooled with this for 30 years.
Never got it to work worth a damn.
http://www.rotaryeng.net/Stratfied-charge-rotary.pdf

Paul Lamar