IAT placement

[Dave Zug]

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