Mailing List flyrotary@lancaironline.net Message #7964
From: Russell Duffy <13brv3@bellsouth.net>
Subject: RE: [FlyRotary] Re: first flight Tracy's old prop.
Date: Sun, 9 May 2004 13:05:24 -0500
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Message
You've probably mentioned it before Rusty, but I can't remember, too much message traffic. What parts is your engine built up from? How does your porting, rotor weights, compression ratio, etc. compare to Tracy/Ed? 
 
My engine started as one of the new generator engines, which was basically an 87 turbo block.  I had Bruce convert it to 9.7 rotors, and port it, so the engine is identical to Tracy's.   

When I built my new intake manifold, I initially had the runners too long, and lost over 100 RPM. Shortening them back to the stock length, I got the power back. So the short intake could be robbing some power.  
 
For all practical purposes, my current runners are about 50 inches long.  Primary and secondary come together almost immediately, then run through about 30 inches of 1.75" aluminum tube.  The TB is a TWM, which has two throats, so each throat is connected to one rotor.  The input air to the TB comes from two separate SCEET tubes that run from the bottom of one radiator duct to the throat of the TB.  
 
Rather than flying today (I warned you this would happen), I'll be pulling off my cowl to do a few tests.  First, I'll replace the plugs, and see if static goes up.  Next, I'll disconnect the SCEET tubes at the TB, to eliminate that length of tubing and try again.  I'll also be finishing the bulkheads that will block off the rear of the cowl cheeks, so it's unlikely that I'll have time to fly, though there's a chance I'll sneak in a beach run later in the afternoon.  
 
Rusty (gotta go)

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