IAT placement

[CSH-HQ]

I'd think knowing the Grm/sec, and temp either pre or post turbo would 
result in the same calc..  THe difference being again, rather read cool on 
heat soak and be rich then lean while temp drops from heatsoak
   On the AUJP cal for the 730 tisting the IAT Pot always got a change in 
injector duration, all other things the same.  So in this calc., I can state
it as the truth.  Trouble is I stay away from universal GM truths, cause I 
ain;t seen one yet.
Grumpy


>In the buick GN the IAT is away from the engine just after the filter 
>housing. now the air thats entering the engine has to pass thru the 
>turbo and the intercooler.. I always wondered what was up with that 
>setup. maybe its not used in calc's I dont know. Grumpy's "some say" 
>statement may be the assumption used in a NA car but IAT PRE TURBO -? 
>I'm sure theres a reason, or maybe it just dont matter.
>
>In an 89 7727 turbo v6 app that I messed with (the only one I got 
>that deep into), the IAT was not even used in any calculations that 
>I could find. it was read once and put into the datastream thats all. 
>made for a convenient ram location to point other things to so that 
>the scan tool could see internals (although the value would be 
>temperature converted). seems I remember that colant temp is used as 
>air temp during startup in some app.  (hows that for vague)
>
>$0.02
>
>> Date:          Fri, 29 Oct 1999 08:04:08 -0500
>> From:          Jared Tschetter <jtschetter at vermeermfg.com>
>> Organization:  Vermeer Mfg. Co.
>> To:            gmecm at efi332.eng.ohio-state.edu
>> Subject:       Re: IAT placement
>> Reply-to:      gmecm at efi332.eng.ohio-state.edu
>
>> I would agree with grumpy, one of the 4gen f-body tricks is to move the iat
>> further to the front of the air stream to keep it as far away from the heat
>> soaked TB as possible.  The air might not be any cooler coming by, but if the
>> sensor is hot already it might skew the results.
>> 
>> Jared T.
>> 
>> > Collective?
>> > Some say the air ain't in the tract long enough to pick-up much heat.
>> > I can see pre TB as fine, also, unless you like drag racing in heat soaked
>> > conditions.  From the time I've had playing with the IAT, cold really 
made a
>> > difference, ie AIR like <50dF.
>> > Grumpy
>> >
>> > >What's the collective thought on placement of the IAT sensor?
>> > >
>> > >On the TPI the IAT was originally in the manifold; on my setup I can 
put it
>> > >either in the airstream ahead of the throttle body, or I can drill & tap a
>> > >hole in the intake for it.   Obviously, the first is the easier method.
>> > >
>> > >I would think that a sensor in the manifold would read a few degrees 
higher
>> > >due to heat transfer from the motor into the intake, and the ECM might 
take
>> > >this into account (or vice-versa).
>> > >
>> > >
>> > >--> Bob Valentine
>> > >--> bob at tecmark.com
>> > >
>> 
>> 
>> 
>~~~
>Dave Z. www.delanet.com/~tgp
>