Ed,

I am using 1 =BE secondary and 1 = =BD primary tubes. That is what matched the port size on the engine (when deformed = to the oval shape of the port). The lengths of the runners are eight inches = from the side of the engine. The runners terminate into a 4" manifold log and a = 65 or 70 mm T/B. My plan is to build a new manifold log with velocity = stacks and then experiment with different length radiator hose for runners. I know = this is not optimal for flow but it should get me in the ballpark quickly. Any suggestions are appreciated.

Thanks,

Jason

From: = Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson
Sent: Sunday, July 30, = 2006 8:04 AM
To: Rotary motors in = aircraft
Subject: [FlyRotary] Re: = Back in the saddle again!

From the opening of the intake port (inside the = engine) to the center of my throttle body my intake length is 22". It = appears that a length between 17-24" is workable and gives good = results. Tracy use a = similar approach (from which I stole a lot of ideas) and also got excellent = results when he was flying a 13B.

Since I use the stock cast lower and part of the = upper cast (which I cut the cast tubes off and install my own light weight tubes) = the actually length of my tubes is 7-11 inches (adjustable - tubes inside = tubes) . That is the length between my cut-off upper manifold (the one = with the 90 deg bend and cast tubes) and bottom of my throttle body plate. However, The crucial distance of course is from intake port to throttle = body - not how long the tube portion itself it. I use 1 = 1/4" dia tubes for the primary and 1 1/2" dia tubes for the = secondary. To make an adjustable one I have a 1 3/8" dia tube over the 1 1/4 and = a 1 5/8" tube over the 1 1/2" - but of course you don't need to = do that.

Too large an intake tube appears to diminish the = mixture velocity and inertia and decrease the amount of mixture stuffed into = the combustion chamber, so while large intake diameters are fine for the = 9000+ rpm racers, they don't appear to offer what we need at the rpm we operate = at.

Here is a photo of my most recent intake and one I = have flow with for 3 years. The blue throttle body mount is make out of a = two part polyurethane casting resin and I use a 65mm Mustang TB. Here is a = photo.

----- Original Message ----- =

You are correct! I have the 2.85 = drive. I scraped the tangential muffler and now using spintech muffler. I = received my velocity stacks last week, so it on to rev "B" intake. By the = way how long are your runners?