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From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-1515629@logan.com>
Subject: Re: [FlyRotary] Re: Injector bosses
Date: Mon, 30 Oct 2006 20:36:17 -0500
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>
> I may have some (a lot of) mis-information in my head.  I had assumed
> that the injectors in the block were the secondaries because those
> ports are smaller.  I'm not actually using injectors in that location
> as all of my injectors are in the tubes feeding the ports.  Will I have
> any problems using the smaller ports as secondaries and the larger ones
> as primaries?  Would it be different if I had the injectors in the
> block?
>
> Bob W.
>
>>

No, just the opposite, Bob.  The injectors in the center housing are the 
primary injectors fed by the two small port openings in the center of the 
intake manifold (stock).  The secondary runners are larger in diameter than 
the primary runners in the stock manifold.  This permits the secondary 
runners to flow more air easier as the demand for air increases as rpm and 
power goes up.  Generally the primary injectors are on all the time from 
idle to WOT (one reason they are called primaries) whereas the secondary 
injectors are normally only on when the demand for more fuel (rpm and power 
increasing) reaches a certain point.  This is referred to as "Staging" where 
it goes from 2 injectors (primaries) to 4 injectors (Primary + Secondary) 
working.  If you are using stock 13B Mazda injectors the engine will run at 
approx 90 % power on either pair of injectors.

Also the intake port   timing is different (in the stock block), with the 
primary ports opening sooner than the secondary ports and the secondary 
ports closing later than the primaries (it varies a bit from one year and 
model (N/A vs Turbo)).

But, its really not a problem Bob.  All you have to do to make the two 
center housing intake ports correspond to your primary injectors is to make 
certain the electrical connectors from the primary injector wires of Tracy's 
EC2 go to the injectors feeding those ports.  Wait, I guess it could make a 
difference if the flow rate of your primary injectors and secondary 
injectors are considerably different.  Mine are the same flow rate - so it 
doesn't matter.  If your injector flow rates are different then you want the 
smaller flow injectors feeding the center housing ports and the larger flow 
injectors feeding your secondary ports.

Your engine would run with either set up - but I would highly recommend 
setting it up conventionally.

Ed

Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.dmack.net/mazda/index.html