Throttle Body Size

[Jonas Hageberg]

Nice formula, but can anyone explain to me why the throttle body
size is important in a plenum intake EFI system? In my opinion, it just has
to be big
enough to let the required amount of air in, since you do not need a certain
air speed to keep the fuel atomized, and the acoustics/tuning is maintained by
the tubes connecting the plenum and the intake valve.
The only problem I can imagine with a too big throttle is unlinear throttle
response.

Can anyone explain this to me?

Regards Jonas Hageberg



>
>Based on a glance at some US cars, I'd try:
>
>TB_Diameter(mm) = SQRT( Horsepower / TB_Blades ) * 4.25
>
>This seems to work for naturally aspirated cars with a single- or dual-
>blade throttle body and a common plenum.
>
>Give it a try.
>--
>Chuck Tomlinson
>