How important is IAT sensor placement

[samh_08]

I recently swapped a heads/cam LQ4 into my 86 monte. My air induction is made up of an aftermarket flex pipe sorta deal and there isn't a decent location for mounting the IAT sensor other than right in front of the throttle body or right after the air filter. Right now I have it sitting where it gets a pretty good mix of fresh air and engine heat.

IAT temps are at ambient air temp at start up and climb when there is little air flow. I havent seen IAT temps over 100*F from where I have it.

So back to the question, How importance is the accuracy and location of the IAT sensor? Thanks guys :cheers:

[mr.prick]

IAT is important, high IAT will lean out.
Don't feel too bad about placement,
us Fbody guys have it in the airbox above the radiator.
This raises IAT a minimum of 10°F above outside air temp.

[1BadAction]

where ever the IAT is at, make sure that your tune adjusts correctly for it. Personally I like to locate them where they will get a reading that is as close to the actual intake air temp as possible.

[samh_08]

Sounds good. Say I am off 5*F in some situations, how much of a effect will it have?

[N0DIH]

What 1BadAction says, It needs to be measuring the air temp of the A/F in the chamber, so placing it far away screws up more than it helps. A light throttle will have warmer air going in the chamber, a heavy throttle it will get closer to ambient.

Moving the IAT into a location farther away from the chamber, the more inaccurate it is. Moving it closer to the TB, if not inside the intake next to one of the intake ports, would be most ideal. The 4.9L Cadillac V8 actually had a screw in intake IAT sensor. The temps swung wildly based on TPS position.


Sounds good. Say I am off 5*F in some situations, how much of a effect will it have?

It will toss off the LTFT's the more it is off from actual cyl temps.

[samh_08]

Makes sense. So if I mount it right in front of the throttle body I wont be causing a restriction in air flow? That is really my only option as far as having it closest to combustion...unless I drill and tap a hole in the intake itself..

[N0DIH]

I honestly don't think that the IAT would be any significant opposition to flow, not measurable to the rear wheels at all. The sensors are pretty small.

If someone wanted to use the in intake sensor, 91-94 4.9L Cadillac V8 in the Deville is the part to get. It has a metal base and visually from the outside it looks like a CTS, but the sensor side is IAT, just has a brass mounting to it.

My 94 LT1 has the IAT in front of the mech fan, which blows all the time, and I read darn close to ambient all the time. It might creep up when stopped, but the actual temp in the intake air there is heating up as well, looking carefully at the sensor you can see that the sensor body will not heat up and make the readings incorrect.

One of these days I need to get out the thermocouples and prove it....



Makes sense. So if I mount it right in front of the throttle body I wont be causing a restriction in air flow? That is really my only option as far as having it closest to combustion...unless I drill and tap a hole in the intake itself..

[Chevy366]

I saw a article in Hot Rod (Roadster) mag , about how to create a IAT sensor mount in the intake on the passenger side of the intake .
On my LS1 truck intake there is a spot that they were using near front of intake, it is about 1" in dia with some webbing and has a screw pedestal just above it .
They drilled the 1" hole to a square bottom depth leaving material , inserted a metal disc where IAT sensor mounted and used a finger plate (like a old style distributor hold down plate) with screw to retain the newly installed piece .
Have looked for the article but have had no luck , anyone else seen this done ?
Would like parts list for MOD , someone said older LS1 or LT1's had a IAT there .

[Chevy366]

Think I found it finally :http://www.classictrucks.com/tech/0903clt_chevy_ls1_engine_setup/photo_08.html
http://www.turnkeyenginesupply.com/

[samh_08]

Excellent find. It looks like the actually sell the kit. I'll have to give them a call tomorrow for more details.

Does anyone advise against mounting it there?

Thanks again for finding the link :cheers:

[mr.prick]

You can try a 5 wire MAF, those have an integrated IAT sensor.