marc wrote:

What say you to the usefulness of a 70mm throttle body for a turbo 3
rotor? What size is ideal? Seems I remember some discussion on this
previously.

Marc Wiese

In an aircraft with Tracy's computer any pressure drop across the throttle
body is a loss of power. The bigger the better up to the point where
you cannot measure the pressure drop. I guess around 100 mm to be that
point.

Paul Lamar

"Brian D. Cain" wrote:

Interesting thread here.  I'm not sure of the relevance to aircraft use, but
there's a
modification that I offer that entails removal of both dashpots and
bracketting, the
thermowax and hardware, as well as the secondary set of throttle butterflies
and
rotating shaft.  From there, I remove excess aluminum and modify the inlet
portion
of the throttle body where the intake charge is moved through.  I remove the
four
"flat spots" (perpendicular to charge flow), expand the widths of the
"throats",
and sand/finish the walls to partial mirror finish.  The idea behind it is
to remove
the turbulent spots on the inlet side of the body to prevent the pressure
drop that
Paul's mentioned here.

I do this modification for the street-driven vehicles that I work on, tune,
etc.  The
purpose of it is for low to mid-RPM throttle response and acceleration,
increase
of low and mid-range torque, and increase in peak horsepower and torque.
Although it has a dramatic effect on a platform for automotive use, I'm not
sure
if it's efficacious or worthwhile for aircraft use.  I'm not sure how it
would play
out for an engine that remains at a constant 5000rpm's driving a propellor.

Attached are two pictures.  Let me knoe what you think, Paul.  I'd like to
do one
for an already operating aircraft setup (like Tracy's) as a before and after
test
to see if it'll make any positive difference or not; I'd be very curious
about it.

B

__________________
Brian D. Cain -/- Grand Prairie, TX -/- bdc196@comcast.net bdc@teamfc3s.org
BDC Motorsports - Performance Rx-7 13B Rebuilds, EFI tuning, etc.
MSN bdc196@hotmail.com, Yahoo! bdc196, AOL Symajhi, ICQ# 1733105
http://bdc.cyberosity.com -/- http://groups.yahoo.com/group/HaltechSupport 

Nice work Brian.

Paul Lamar

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