Air Volume Calculation

[Walter Sherwin]

A really rough rule of thumb for a single monoblade wide open throttle
airflow rate is 140 cfm (@ 1.5"Hg pressure drop)  per square inch of open
throttle area (total bore area minus the throttle shaft cross-sectional
area).    Greatly oversized monoblades can reduce the pressure drop loss,
but they can also introduce tip-in control and part throttle driveability
problems.  Sometimes you can fabricate/attach a decreasing radius linkage to
mechanically "slow" the initial monoblade rotation with respect to
accelerator pedal travel if the later issue is a problem.

Have Fun;
Walt.



-----Original Message-----
From: Anthony Gordon <tgordon at saginaw-city.k12.mi.us>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Sunday, January 17, 1999 12:12 PM
Subject: Air Volume Calculation


>I have a Triuph mechanical injection system on a 72 TR6.  Using a O2 sensor
>helps tune the system, but it would a lot easier to tune if I could
>eliminate the 6 separate throttle butterflies in the throttle bodies which
>causes great synchronization problems.
>
>The engine is a 2498cc unit, and produces max BHP at 5300 rpm.  Is there a
>calculation for the optimal area/size of a single throttle body that I
>could use?  I am hoping that I can re-use a throttle body from a junk yard
>so suggestions on type as well would also be most helpful.
>
>TIA
>
>Tony Gordon
>
>