DIY_EFI Digest V1 #186

[talltom]

> ------------------------------
> 
> From: "Josh Karnes" <joshk at tanisys.com>
> Date: Mon, 1 Jul 1996 10:09:38 +0000
> Subject: intake runner length
> 
> 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 :)
> _____________________________________________________________________________
> 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
> _____________________________________________________________________________
>            *** opinions expressed herein are MINE, ALL MINE!! ***

Well if the exhaust is is heating your intake air because the flow meter is
close to the exhaust and this is causing it to run rough at hot idle, I should 
have the same problem but three times as bad because mine is turbocharged and
makes much more exhaust temp. Mine idles fine hot. Personally I think the 
intake was well designed and if you cut it up you may be able to get more
horsepower at about 500 rpm past where the rod let go! These things redline
at 6500. I keep saying fix what's wrong with yours, and you keeping wanting
to chop it up. From here on in I quit! Have fun!