IR throttle bore sizing (Re: [Diy_efi] : Ask the experts #2)

Bruce nacelp at bright.net
Mon May 20 20:26:06 GMT 2002


Alan Lockheed has some engine analyse software that as I recall used a
number similiar to that.
Bruce

----- Original Message -----
From: "TVS" <tkmvs at bigfoot.com>
To: <Diy_efi at diy-efi.org>
Sent: Sunday, May 19, 2002 9:24 AM
Subject: IR throttle bore sizing (Re: [Diy_efi] : Ask the experts #2)


> > On the IR stuff the Throttle bores are generally huge.  Like on 350
chevy
> > each one is like a min of 2".   AIR, some were more like 2.35.
>
> I read in Corky Bell's "Maximum Boost" that throttle bores should be sized
> so that the average velocity does not exceed 300ft/sec. This is supposed
to
> give a good compromise between low speed driveability and flow restriction
> at maximum power. Does this sound about right?
>
> For my 998cc, 4 cylinder engine, 4x 1 1/4" throttle plates would give
> 260ft/sec assuming 8,500RPM and VE=0.9.
>
> Are there any other 'rule of thumb' sizing numbers?



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