Hi Buly,

I have tired throttle bodies as big as 75mm, I went back to a 65 mm Mustang Throttle body.  Here is what I found.

The larger throttle body provided no measurable increase  in power produced - in fact, the power actually went down as my static fell 200 rpm. I did find that suddenly opening the large 75mm TB would cause the engine to bog and hesitate for a second.  It was suggested that I push the throttle in more slowly, well, Scotty, when I want full power I want it NOW!

In any case, I now fly and have flown with the 65 mm for 3 years.  I can turn 6000 rpm static on a standard day and upto 6200 static on those wonderful cold mornings. I can shove the throttle in as fast as I  can and there is no bog or hesitation.

That is what my experience has been.  For a full up all out race engine, I am certain Paul's suggestion has merit, but for our usage, I did not find a large TB provided any improvement and actually make flying less pleasant.

Ed

----- Original Message ----- From: "Bulent Aliev" <atlasyts@bellsouth.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, April 29, 2007 6:05 PM
Subject: [FlyRotary] Throttle body size

I originally planned and tried TA set up on my Cosmo 13B. Soon after  the first few flights removed the turbo and vent NA. At the time did  not pay much attention on the throttle body size, counting on the  turbo to make up for any losses. Today I measured the inside opening  of the TB and was surprised to find it was only 60mm. This is rather  small. Paul Lamar on his visit also said I should get a bigger one. I  wander what size TB other people are using, or any comments and  suggestions on the matter will be helpful.

Buly





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