Runner Lengths

[Bruce Plecan]

> I'm making a MPI system for my Chrysler 265cu (4.3l) inline six hemi
motor.
> I'm going to be using Ford 4.0litre injectors, and two XF falcon throttle
> bodies (70mm diameter).

Unless your' spinning it to about 14K RPM seems like alot of Air.

> I have two manifold idea's in mind. The first is, (the ascii drawing
below)
> a straight pipe (90mm) with 6 smaller (50mm) diameter pipes going to each
> inlet port. The two 70mm Throttle bodies will be mounted on a flange on
the
> 70mm pipe, equally spaced apart.
> || || || || || ||
> || || || || || ||
> |-----------------|
> |  XX      XX     |  XX = Throttle body.
> |-----------------|
     _______        _______
> a  (   XX  )======(  XX   )
>    / /| |\ \      / /| |\ \
>   / / | | \ \    / / | | \ \
> / /  | |  \ \  / /  | |  \ \
> XX = throttle body.
> ===== - balance tube
> I have a few questions:
> 1. Is there any difference between square intake runners and round?

Surface area for size.

> 2. One the 'first' manifold, would it be better to mount the two throttle
> bodies next to each other, or on either ends of the manifold, or equally
> spaced?

Seems like one is more then enough.

> 3. How long should the intake runners be? what are the
> advantages/disadvantages?

Track down Bruce Bolwing formaulaes they're on the net somewhere.

> should i use MAP or MAF?

Hehehehe, MAP
Bruce


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