On Saturday, January 22, 2005, at 12:19 AM, Tracy Crook wrote:

 

> 
> I'd bet that the better BSFC with remoted injectors that's hyped on the
> other list was only achieved (wasn't the info from the Mazda factory
> racing program?) with perfect injector placement & timing based on more
> testing than any of us can do in our proverbial garages. (Is injector
> timing variable on Tracy's or any other injection controller out there?)
>
>  >From one neophite to another....
>
> Charlie
> I think that better BSFC report was from the Racing Beat 3 rotor 900
> HP turbo engine project.  I think this is so far removed from what we
> are doing that it's not applicable, even if true.
> 
> BTW, The EC2 does use port timed injection.
> 
> Tracy

Understood, but does it matter that the timing of each injection
relative to the port open/close cycle changes when the injector is moved
from the block to over a foot away, & can it be adjusted like ignition
timing?

Charlie

Good point, I missed the full implication of your original question.  No, the injection timing is not separately adjustable and I don't know if that would help in the case of large displacement from the port.  One important thing to note is that the air volume in the long runner can be larger than the intake charge at low throttle.  This makes it virtually impossible to properly time the injection pulse of a "long distance injector" without knowing the future, if you get my meaning.
 
Tracy  (marking this down as #9999 on list of things to try)

Tracy and all, I asked Rolf Pfeiffer to look at this issue. Rolf has been a tremendous help to me in designing my p port size and timing. He is a retired engineer with a very long background in the rotary going back to NSU. He is not a member of this list but I am working on that.

Here are Rolf's comments;

Looking in more detail at the intake and injection it is quite interesting.

First we look at a “first” chamber that is at the end of its intake stroke. Just after its BDC the apex seal is reaching the closing edge of the port and the port begins to close. At that same time however, the next or second chamber that is at its exhaust stroke is opening to the intake port. At about 69 degrees ABDC the intake to the first chamber is fully closed.

During these 65 degrees or so, actually for the whole next 90 degrees, we have the incoming fresh air flow to chamber 1 and in opposite direction the exhaust gas flow of chamber 2. It now depends on the pressures of each air mass in which direction both air volumes flow. Undoubtedly, there is mixing taking place. Presumably, the hot exhaust gas will push into the intake port and runner. At 90 degrees rotation after BDC of the first chamber, minimum volume of the second chamber has been
reached and suction begins where fresh air again starts flowing in the intake runner and into the second chamber.

Presumably, at this point, when suction begins, Tracy is starting to inject fuel, which is about 90 degrees after the port has been open and is at BDC of the chamber. Again, I presume that the injector has a constant flow and the amount is determined by time the injector sprays. The end of injection at max power should then be near BDC or before. The window is between 0 and 270 degrees or better more like 15 to 240 degrees. At a speed of 7500 rpm the maximum spraying time is then over 225
degrees shaft rotation or .005 seconds. The interval time is .008 seconds.

The funny thing is, if you spray at the bell mouth, it takes a complete cycle for the air and fuel to reach the chamber. In other word, the timing should be the same, but when you inject it will reach only the next chamber, not the one it would serve if the injector is close to the intake port.

However, I see no problem with this. In fact due to the back flow you may actually get the same effect as you get with a closed intake valve at an RPE, where the fuel has time to evaporate, hence the better fuel burn with a far away injector.

Perhaps you should think about that for a while and get back to me, see what you think. One thing though, I would ask Tracy about his beginning and end of injection cycle relative to the crank angle at idle and at full speed of 7500 rpm. I am very interested in how he timed his injectors.

Regards
Rolf