Mailing List flyrotary@lancaironline.net Message #4838
From: Russell Duffy <13brv3@bellsouth.net>
Subject: RE: [FlyRotary] Re: Dumb intake question
Date: Sun, 21 Dec 2003 10:21:31 -0600
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Message
But, since they are not interconnected, can not use the DIE equation.  However, Here is what the calculations come out to using just a pipe from intake port out to your throttle body.  I assume from your comment that you don't have a lot of length to deal with.  I further assumed you do want to get some help from Intake "tuning".   
 
I either have about 28 inches over to the right cheek, or something much shorter in the left cheek.  If I can work with either of these, and get some intake tuning out of it, then I'll give it a shot.
 
 So based on that - it looks like your length from port to butterfly inlet of TB ranges from 13.1" for 6500 RPM to 11.5 RPM for 7500 RPM.  This provides time for the pulse to be generated by the closing of the port and to arrive after that port opens again after bouncing back from the throttle body once.  So from that Length you would need to subtract your block to port distance of 2.5" and the length of your throttle body. 
 
Excellent!  This is just the sort of info I was hoping for, but there's one thing I still don't understand.  When you say the pulse bounces back from the TB, what is it bouncing off of?   I believe the throat of the TB is straight, with no venturi effect at all, and we'll assume that the intake runner matches the TB size perfectly.  That just leaves the open butterfly, which has a pretty small profile.   Is it really getting a strong bounce from the open butterfly?  What if you had a slide type opening, like the Ellison TB, where there is nothing left in the path of the air?  Would there just be no bounce?
 
Thanks a bunch,
Rusty (special needs student)
 
PS- Somewhere, I know I've seen a short intake, that points straight out to the side, and uses a side draft carb.  I've been looking for that all morning, and can't find it now.  Can anyone point me to one of these?  I'm thinking it might make a good starting point for a left cheek intake.  Thanks. 
 
 
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