Mailing List flyrotary@lancaironline.net Message #8783
From: Russell Duffy <13brv3@bellsouth.net>
Subject: RE: [FlyRotary] Re: Rev-2.1 part 2
Date: Tue, 1 Jun 2004 21:23:33 -0500
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Message
Do you think 48-50mm's would boost power?  Mo mix?  The allout Racing  Beat wrap around intake uses 48MM Webers or Dellorto carbs.  Dave Atkins is really estute with that rig, so what does he say?
TJ 
 
One simple theory says that the largest throat possible will decrease air flow resistance, and let the MAP get closer to the actual ambient pressure.  This ignores the more complicated theory that says that higher velocity air through a smaller opening will help stuff more air in the chamber.   Everything is a compromise, so your best results will be somewhere in between tiny, and huge.  Ed will calculate this for you, since he has no flying plane :-)
 
Seriously, my 40 mm (which I didn't chose) has the same ID as the 1.75" OD tubing that I used for runners.  I doubt they're causing me any problems now, but I do worry that it will be somewhat restrictive when I get to the -C drive, and 7000+ rpm.   If I end up matching Tracy's static rpm with this setup, it will be interesting to see how I do with the higher rpm configuration.  
 
If you want to know what Dave has to say, give him a call.  I've had my last conversation with him. 
 
Cheers,
Rusty (low tolerance for BS)
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