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

[TVS]

> 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?

Thanks, Toby



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