[alfa] head porting, flow reversal

[Joe Elliott <jee@xxxxxxxxxxxxxx>]

I should be doing homework right now, but I couldn't help but follow 
that AlfaBB link about the Suzuki throttle bodies.  Having wasted 
several hours with that and all the associated links, I have a more 
general question.  Somebody on AlfaBB said:

>  It's a given that to leave a step on the exhaust port can help 
>reduce flow reversal with cams that have a large amount of overlap. 
>Surely then the same would apply to the inlet port? Also the sudden 
>pressure drop at that point may induce more flow than a gradual 
>taper would.

Is what they say about the exhaust port/header interface true?  If 
so, which way are they talking about stepping it--bigger header than 
port, or vice versa?  And why does this reduce flow reversal (which I 
assume happens because the exhaust manifold is at a higher pressure 
than the intake manifold).

Thanks,
Joe Elliott
'82 GTV-6 (so rusty that I resorted to autocrossing a Japanese car 
yesterday...)

PS>  What is it with these damned HTML-based forums, anyway?  Why 
can't everyone just subscribe to the freakin' Alfa Digest?
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