No science (or very little) here either but I used 1.75" headers into a 2.25" collector w/ 2.25" in/out of the Spintech.
----- Original Message -----
From: Russell Duffy
Sent: Saturday, December 20, 2003 11:10 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: spintech, and exhaust size
Mine spintech is a little smaller than Tracy's but I don't remember how much. Again, as I remember the guy at Spintech didn't care about aircraft use. Also, there was no scientific reason for the two inch in/out, and some have recommended a smaller diameter, like 1.5 to 1.75.
Thanks for the info Tommy. The non-scientific reason for your 2" in/out may have been that it's the minimum size Spintech lists :-)
I have a couple Racing Beat header flanges, and they have 2-1/8" holes. I'll look at the actual port size, and see if maybe that can be cut down a bit. The smaller diameter pipe would be easier to work with, but I certainly don't want to make it so small that it hurts the flow at 7500 rpm.
What diameter pipe are you guys using? Larger size after collector?
Would #9 "Y-Collector/Center" be an effective collector, or is there not enough pipe after the two join together to provide a good scavenging effect?
Do you get any scavenging effect at all out of a design like #7, with dual inlets, and one outlet.
If you used a design like #10, with dual inlets and dual outlets, and then put a collector after the outlets Would get any scavenging effect?
Sorry for all the questions, but I have a lot of catching up to do on exhaust design.
I plan to be down your way the week after Christmas to fly again. Maybe bring it to NC if it proves itself well enough.
Regards,
Tommy<><
Good luck. I'm sure you'll be happy to have the airplane at your new home.
Cheers,
Rusty (I'm already exhausted... sorry)