Mailing List flyrotary@lancaironline.net Message #42029
From: Michael Silvius <silvius@gwi.net>
Subject: Re: [FlyRotary] Re: Gravity fed carb? peer review
Date: Sat, 22 Mar 2008 11:45:17 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Tracy:
 
The three Mikuni set up works, as you and and Fin Lassen have proven so that is always my fall back if I choose to stay with carbs.
 
Mixture distribution issues apply to the Corvair conversion with its long runners, low mounted carb and its six cylinders. Those with individual cyl head and EGT probes have noted some great variation in indications between cylinders. In order to correct this some of the folks have played around successfully with the "Tornado fuel saver" device theorizing mixture distribution as the source of the problem. A little fan shaped insert that swirls the mixture after the carb and it may be something to look at in this case. In the end it may just be a mater of  building it and see what it does with no or minimal expectations.
It will  be a good point to consider when assessing performance.
 
thanks:
 
Michael
----- Original Message -----
Sent: Friday, March 21, 2008 7:28 PM
Subject: [FlyRotary] Re: Gravity fed carb? peer review

A big factor in carb manifold design is mixture distribution.  Not always easy.  That was the object of those horrid T shaped junctions seen on some aero VW conversions.  Really bad turbulance and pressure loss but it mixed up the mixture pretty good.  The advantage of using separate barrels (or carbs) for each rotor is that mixture distribution is assured.  
Aside from that, your runners are very short so not a lot of ram tuning effect.  The long single runner from the carb doesn't count as it contributes nothing to tuning.   But if all you need is 150 - 160 HP it will work OK (assuming you do get good mixture distribution).
 
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