IAT temps

[Big Kahuna]

Hi guys.
As we're in the middle of summer here in Aus and with local temps regularly in the vacinity of high 30's and low 40's, I thought Id pay someattention to the IAT temps.

Ive notice the biggest issue i seem to get is terrible heat soak if the car is left to sit idling for extended periods such as going thru town with the lights etc.

I have an OTRCAI but even with that it can take some time for the iat tems to settle down. Im also curious as to how much heat soak there is in the actual sensor itself.
On a logged run recently (high 30 degree day) I saw iat temps in excess of 50 degrees whilst stationary. Once on the move again it took another 10mins before the iat temps cam back below 40 and even then they didnt drop much further.

What Im curious to know is what is the ideal position to have the iat sensor??

Placing it directly in the air intakes path without anything around it to cause heatsoak would surely be the best scenario wouldnt it?
Having it mounted in the plastic corner of an OTRCAI cant be ideal as the plastic retains alot of heat even with some airflow thru it, and the air flowing thru wouldnt be increasing in temp that much. Ie the air being ingested wouldnt equal that of the sensor reading.

Would it be wise to mount the IAT sensor in the direct path of the airlfow into the intake but away from anything that could cause heatsoak into it??

Grant

[Tordne]

Temp sensor should ideally be located as close to the TB, but also away from areas where it will get heat soaked and effect the measured IAT.

You may want to look at the A0014 table in COS3 or 5 as a VE multiplier based on IAT temp. Works very well. Not sure if you had values for this in your tune or now...

[Big Kahuna]

Temp sensor should ideally be located as close to the TB, but also away from areas where it will get heat soaked and effect the measured IAT.

You may want to look at the A0014 table in COS3 or 5 as a VE multiplier based on IAT temp. Works very well. Not sure if you had values for this in your tune or now...

Yeah those values are populated to take into account for the warm weather. Im not getting any KR in the upper range with warmer iat's.

The closest position to the TB without any heatsoak interference is situated behind the front bumber at the opening to the cold air intake. That doesnt however take into account any heatsoak the in-comming air might receive as it travels thru the intake, albeit less than a 30cm path.

I think some heat sheilding on the underside to the OTRCAI might be a valuable addition also.

IS this a topic others have investigated?
Perhaps I should make an OTRCAI out of esky (chily bin for you Kiwis) foam. that'd solve any heatsoak issues! ;)

[Tordne]

The IAT needs to be closer to TB IMO, as you say there is heat soak from the point of temp measurement to intake.

I put some heat shield on the bottom of my OTRCAI and surprisingly/disappointingly it seemed to make 0 difference :mad:.

What sort of OTR is it? Mine is a G&D one :)

[ScarabEpic22]

Have you guys heard about Vector Motorsports IAT setup? I dont know if it would work with anything but the LS2, but if you are interested give them a call or email.

It uses a much faster responding IAT sensor that is moved away from the MAF (basically allows you to put the IAT sensor in the airbox for the truest IATs possible). It is $99 USD, but for LS2 people, especially TrailBlazer SS guys with huge heatsoak issues, it really helps their times and driveability after idling at a stoplight, etc.

Check it out at: http://www.vectormotorsports.com . (If this is a problem mod, feel free to remove it.)

[Jetmech442]

I had to split my IAT from my 5 wire MAF in order to do VE tuning with wideband. While I was at it, I hooked up both the LQ9(5 wire) and the LS1 IAT to my data acquisition box. I mounted both IATs at the same location in the middle of 2 feet of tubing(6'' diameter). For airflow, I used a hair dryer on both cold and hot settings. for the first 20 seconds there is no flow, the sensors are reading ambient temps of 62 F. During this time the hair dryer was on hot and blowing away from the sensors(this allowed the hair dryer to settle at 150F as meadured by a calibrated temp gun). At the 20 second mark I put the hot hair dryer in the flow path. You can see the LQ9 sensor takes about 20 seconds to level off at 150F, whereas the LS1 takes about 40 seconds.

At 60 seconds I turn the dryer off. They both fall down to roughly ambient, and then I turn the dryer on cold.

Conclusions I draw from this:
1) Up to about 120F, both sensors would provide teh same temp readings and react equally fast.
2)If the sensors are not heat soaked, they will react to changes in temp fairly fast-not sure what the cfm of the hair dryer was, but I'm asuming even an ls1 at idle would be more.

I would like to do another run where I blast the sensors themselves for several minutes to get them up to 150, and then see how long it takes each drop back to ambient with the cold hair dryer running. Sorry if this makes more questions than answers, my orginal intent was to see if the sensors would report the same temp without a change to the tune.

http://i1163.photobucket.com/albums/q555/jetmech442/Mobile%20Uploads/IAT_Graph.jpg (http://s1163.photobucket.com/user/jetmech442/media/Mobile%20Uploads/IAT_Graph.jpg.html)

[joecar]

When doing VE tuning, make sure a MAF DTC is present (regardless of disconnecting the MAF sensor).

I hope your IAT does not reach 120F when your engine is running... if it does then you need to redirect the plumbing to find cold air.

[Jetmech442]

When doing VE tuning, make sure a MAF DTC is present (regardless of disconnecting the MAF sensor).

I hope your IAT does not reach 120F when your engine is running... if it does then you need to redirect the plumbing to find cold air.

Thanks for the tip Joe. I'm not sure my IAT would hit 120, but maybe boosted applications would.

OP, after reading everything again, I feel like my post above was unhelpful and would have been better posted elsewhere. My intention was to quantify IAT response time, but since it doesnt account for a heat soaked sensor, I think it doesn't answer your question.

For reference, I placed my IAT about 2 inches from the throttle body. I did this based on previous searches and no real data. Once I get driving, I plan to record both the current location and temps in the airbox and see what the temp diff is(I am using a stock LS3 intake tube).