intake runner length

[Josh Karnes]

what is the effect of the runner length on the intake manifold?  In 
my car there is the head, then there are some little runners about 2" 
long wherein the injectors are mounted, then attached to those 
runners are some long (like a foot) "U" shaped runners that curve up 
so right above the cam cover it connects to the intake plenum, 
throttle, etc.

What I have considered doing is somehow relocating the intake plenum 
over to the intake side of the engine, since currently all the intake 
plumbing sits right on top of the exhaust manifold where lots of hot 
air is while the car is idling (in traffic, causes it to run really 
rough after idling in traffic, stall, etc.).  However, if I 
fabricate runners that are as long as the stock runners, like a foot 
or more, it won't fit under the hood.

So what will the effect be if I shorten these runners, or just bolt 
up the plenum right onto those little 2" runners (it looks like it'll 
bolt up).

Thanks :)
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Josh Karnes                                                 joshk at tanisys.com
Renaissance Man                        http://www.tanisys.com/~joshk/home.htm
Tanisys Technology                                     http://www.tanisys.com
Austin, Texas                      '78 BMW 530i | '72 Datsun 240Z | IZCC #308
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           *** opinions expressed herein are MINE, ALL MINE!! ***