Paul,

   This week I will sand blast a housing, and fill the outside depression
   around the oil
    injection location with DEVCON Aluminum epoxy.

   Thursday afternoon has become my access day for  Michiwa's school
   machine workshop and I will be boring the housings and making the
   aluminum inserts then.

   Pictured below are two types of injector cylinder housings, both with
   upper and lower 0-rings.  The design on the left has a M-20 thread on
   the top part though it isn't shown, and although it takes up less real
   estate I have decided to go with Lynn Hannover's design suggestion.
   Why?  O-rings tend to deform or fold when they are twisted several
   revolutions while being pushed axially as well.

   I'll pressure test the housings with some glycol/water mix in the cavity
   to confirm it works.

   FYI the injector interface to the inner liner hole is drilled and V
   shaped from the backside to allow the injector tip to insert with about
   0.5mm clearance of the apex seal path.

   Since I am supercharging the
    engine and wish to stick with MAP and
   MegagSquirt ECU,  the question remains where to put the sensor or
   fitting?

   Two choices.  The present oil injection hole, or in the back plate on the
   slide throttle?
   I am concerned that the oil injection hole may accumulate fuel in it
   during certain engine events, so I am leaning towards the slide throttle
   location now.

   Cheers


   Doug in Japan

   Don't forget to prepare the aluminum with an etching solution.

   Question: when does megasquirt sample the manifold pressure
   and is the short sample representative of the air going in the engine
   throughout
   the RPM/tuning range? Have you studied the C source code to find out?

   What are you going to use for a throttle position sensor?

   The O2 sensor will fail if you use 100LL.
   How important is the O2 sensor to proper operation?


   Paul Lamar



I'm considering something similar and have three questions:

1.  Is it not practical to use the standard Mazda 13B injectors through
the oil hole?

2.  Is this the Megasquirt shcematic?

3.  Could you point me to the Megasquirt code?  I did a quick search and
probably gave up too soon.

Thanks,

Philip

It has been tried many times.
Here is the fundamental problem. The pressure builds up in the intake
chamber once the intake port closes reducing the flow of fuel.
At high RPM there is too little time to get all the fuel in there before
the port closes. This can be delt with by upping the fuel pressure. Nobody is doing this now except Doug.  I await his results.

Another problem is atomizing the fuel. Diesel injection is good evidence of this as diesel injection pressure is now up to 20,000 psi. The longer the fuel is in contact with the air the  more time it has to evaporate and mix throughly with the air. Several people have noticed an improvement in BSFC  and this is one reason race engines inject the fuel into the intake bell. Mazda among them on the Lemans engine. However Mazda needed quick throttle response so they moved the injectors closer to the rotor housing.  Others, Mistral among them ,don't think this is the case. So you take your pick.

Paul Lamar