Any opinions on this?

I have a theory, which is that using begging of injection and timing the injection event to begin after the port is half open, and the rotor tip is past or almost past the exhaust port would minimize fuel lost to port overlap, for places on the map where the the injection time was low.

Any thoughts on this or reasons this wouldn't be at least somewhat effective in some situations?

 

I found the thread below which may help explain the angles that are run from the factory. My thoughts are start with them. I have not played with the injection phase angle yet on an E6X, but it might be interesting to see how it affects tuning. Any thoughts on where to start? Currently sitting at 20 deg across all rpm ranges.

https://www.rx7club.com/showthread.p...njection+angle

 

The problem with using beginning of injection angle is that when revs increase and the amount of time available for a given cycle shortens you can easily have a good portion of the injection phase spraying on a closing port. If there is reverb in the runner at port closing that will complicate the situation.

By using end of injection angle the ECU will automatically calculate the proper time to start the injection phase so that it ends when you desire. The way I see it it is better to injected fuel in a closed runner that is opening rather than trying to shove fuel into a port that is closing or has just closed.

The benefits I've experienced are mostly at low revs. Like sequential v. batch injection, the benefits seem to lessen as the revs rise. At a high duty cycle at high revs you're injecting fuel outside of what would be considered the optimum period anyway. And there is simply no way around that without lowering duty cycle dramatically.

 

This makes sense, as you pointed out when you mentioned seq vs batch either could and would work with little real difference between them, but I think using end of injection with the ending set just before the actual closing point of the port would be the way to go, this is what I actually ended up doing and managed to get a much leaner idle.

 

i remember when we were setting up my 20b fc we played with that, we were lucky to just have the new model training book for the cosmo, and it had mazda's injection timing map in it. i think the rx8 training book does too

i remember it didnt make noticeable difference, playing with it at idle, although it was a 3 rotor, and we didnt have it hooked up to any instruments or anything

 

The leanest "good" idle I was able to get before adjusting the injection angle map was 12.7-1, after adjusting that, and the battery correction map, and some IGN changes, and some others I got it idling just as good at 13.7-1

 

Don't use AFR's as the only guide for the leanest or least amount of fuel used for idle/cruise etc.
AFR is only a ratio. Use injection pulsewidth as your guide. The lower the PW the least amount of fuel is being used/wasted. You gan get the same AFR with different PW but the AFR with the lowest PW is the one using the least amount/volume of fuel.
Oxygen sensors only measure the amount of oxygen in the mixture. Unburnt/wasted fuel in the mixture show up as lean on an O2.
Overly retarded ignition timing will also show up on an AFR meter as being lean when in actuality it's not measuring the wasted or unburnt fuel in the mixture. There again PW will determine the least amount of fuel needed.

 

Love this forum....i learn something new everyday.

 

I was paying attention when you said this in the other thread.

02 sensors also can't measure the fuel and air lost to port overlap because it burning in the manifold on its way out.

I got the lowest pulswidth with just a little bit of neg trail, the WB02 was at that point showing a bit richer with a stable idle even though less fuel was being injected.