Mailing List flyrotary@lancaironline.net Message #28433
From: george lendich <lendich@optusnet.com.au>
Subject: Re: [FlyRotary] Pport advice from the master
Date: Tue, 13 Dec 2005 17:36:38 +1000
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
 Monty see comments below
Who else but Lynn,
 
Well, I just bought a 89-91 NA automatic motor. The plan is to Pport it.
Great 1.75 ID  
 
Basically leave the exhaust alone. Leave the splitters or not? The archives are a bit inconclusive here. In one post Lynn says to keep the splitters. In another he says the Pport is very sensitive to exhaust back pressure. I have some turbo housings I can take the insert out of and put into the NA housings if need be. 
 
I'd leave them alone
 
Other info I have says the exhaust should be ported to Close 55 deg ATDC vs 48 ATDC for stock while leaving the exhaust opening alone.
?
 
Intake timing:
 
IO 80 deg BTDC
IC 60 deg ABDC
 
13 in intake length? Seems a bit short
 
31 in length header primaries 1 7/8-2 in dia - 2"
 
3 in collector into muffler
 
2 in dia after muffler.
 
7500 max power
 
5500-6500 cruise power running LOP.
 
2.17 drive and a 68 in prop. - 2.85 would be better for 7,000+
 
Speed-fast hopefully.
 
If it sounds like this I won't be upset:
 
 
 
Who says they won't Idle? That is music to my ears!! Sewing machine be damned! A proper sound should cause spontaneous incontinence amongst the granolas.
That an old 10A - things are better now!
George ( down under)
 
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