From: kenpowell@comcast.net
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: surging / rough idle
Date: Wed, 05 May 2004 21:29:56 +0000
Message-Id: <050520042129.3193.40995CD4000CA6A500000C792200734840FF93939A88908F919A@comcast.net>

Most of us are old enough to remember carburators and many/most have played with carburated cars in the past.  Despite what Paul L. and others advocate, I would suggest that we remember some of the things we learned from those days past:
1.  velocity in the intake is your friend
2.  fuel 'puddles' if given a chance
3.  correlary to the above, fuel does not like to travel long distance in intake runners
4.  'icing' can occur, even in FI engines if the conditions are right and the intake design is wrong

Suggestions: (see Tracy's suggestions)
1.  Do not use injectors that are to large.  Go to the RC Engineering web site (www.rceng.com) and calculate the size you need based on HP needed and an 80% duty cycle.  (225 HP requires 4 injectors of 38 lb each at 80% duty cycle, fuel pressure of 38 PSI, and a BSFC of 0.5)
2.  Do not mount the injectors that you will be using for idle a long distance from the combusion chamber
3.  Do not use intake tubes that are too large - you NEED the velocity

These are all PROVEN tips practised everyday amoung the car guys.  You may get another methodology working, but it won't be easy (and maybe impossible).

Ken Powell