Mailing List flyrotary@lancaironline.net Message #13890
From: Russell Duffy <13brv3@bellsouth.net>
Subject: RE: [FlyRotary] Re: Injectors
Date: Wed, 15 Dec 2004 08:02:50 -0600
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Message
Using the 440cc injectors may help; but I don’t think there is any assurance that they will work well.  Didn’t Rusty try this? 
 
 I don't remember it, but he may have. 
 
 
Yes, I tried the 440/460 injectors, and didn't see any improvement in idle.  If I'm not mistaken, Mazda rated these injectors at a lower than standard pressure.  For the guys who've had theirs tested, didn't they flow over 500 at standard pressure?  For some reason, I'm thinking that the 550's were rated at normal pressure, and RC Engineering tested 4 of mine with results between 549 and 551.  My thinking is that there isn't much difference between the stock injectors.
 
For idle, response time is more important, and I've always wondered if the difference wasn't between using high and low impedance injectors.  I believe low impedance injectors are supposed to react faster, and you have the option of varying the ballast resistor to give them more or less punch.  This is just a wild theory that I'll never test.
 
Someone also correctly mentioned that Mazda lowers the voltage of the fuel pump at idle.  I don't see how this would change the pressure though, since the regulator will still keep it the same.  I'm sure there's a fuel pressure spec in the shop manual, and it would mention a different pressure at idle if there is one.  Doubt it though.
 
Rusty  

 

 

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