Charge air temp sensor location in plenum?

[BadAssPerformance]

Making a custom plenum intake... I know where the stock charge air temp sensor is located in the 2-pc T2 intake, any reasons to place it at one end or the other or in the middle? shoot!

[Tony Hanna]

Personally, I wouldn't put it in the intake at all. I'd put it in the charge pipe before the throttlebody. This would help keep the sensor from heatsoaking and reading the manifold temp instead of the temperature of the air passing through it.

[BadAssPerformance]

Interesting idea... wouldn't that tell you the air temp out of the intercooler but not exactly the temp of the air as it goes into the head tho?

[shadow88]

Yes, it would be closer to ic outlet than port inlet. I've had mine in the pipe for a couple years as well.

[Tony Hanna]

Interesting idea... wouldn't that tell you the air temp out of the intercooler but not exactly the temp of the air as it goes into the head tho?

Well, the LT1 guys have been relocating IAT sensors for quite awhile. The theory behind it is that the air is moving fast enough at full throttle that it doesn't have a chance to pick up a significant ammount of heat. The sensor itself will pick up a good bit of heat though because it's mounted in an area that stays fairly hot from engine heat and the heat is transfered through the sensor body (heatsoak). Relocating the sensor seems to show some small gains in that application, so I would imagine it would in ours as well. I could be wrong though.

[Frank]

I would do in the neck or the pipe before the throttle body.

[BadAssPerformance]

Well, the LT1 guys have been relocating IAT sensors for quite awhile. The theory behind it is that the air is moving fast enough at full throttle that it doesn't have a chance to pick up a significant ammount of heat. The sensor itself will pick up a good bit of heat though because it's mounted in an area that stays fairly hot from engine heat and the heat is transfered through the sensor body (heatsoak). Relocating the sensor seems to show some small gains in that application, so I would imagine it would in ours as well. I could be wrong though.

I would imagine any gain in power seen is because it is in possibly colder air than what is in the plenum which would make the computer add more fuel. More fuel = more power as long as there is enough air.

My car has a FAST stand alone on it. No matter where the sensor is I will tune it to run. So the question is where would it have the most accurate temp not necessarily the coldest temp?

[BadAssPerformance]

I would do in the neck or the pipe before the throttle body.

Why??

[turbovanman²]

I was told for stock computers, leave it in the factory location.

For you, I would put it just before the t/b, that way, you get an accurate reading.

[Tony Hanna]

I would imagine any gain in power seen is because it is in possibly colder air than what is in the plenum which would make the computer add more fuel. More fuel = more power as long as there is enough air.

My car has a FAST stand alone on it. No matter where the sensor is I will tune it to run. So the question is where would it have the most accurate temp not necessarily the coldest temp?

Well, their take on it was that since the relocated sensor isn't heatsoaking, it's actually reading closer to the true air temp than what it would in the stock location.

Maybe a test is in order... Can you set up the FAST system to log 2 IAT sensors? Maybe put a bung in your manifold close to where it would be in a stocker and another in the charge pipe before the TB. It would be really interesting to see the results.

[BadAssPerformance]

Cannot measure 2 at a time but could measure one then another on consecutive passes. Could use a couple thermal couples in different spots tho.

[Tony Hanna]

Yeah, that would work too. The right way to do it would be to find a way to measure them both at the same time and then graph the results to compare. I would guess that the stock location sensor would start out pretty hot from heatsoak and then cool a little with airflow while the pre-TB sensor would show more of a direct relationship to the actual air temp.
That's just a guess with nothing to back it up at this point though.

[BadAssPerformance]

I have a Omega Meter that can read up to 4 thermalcouples and will show deltas between two of them at a time. To really show air temp I think it needs to be a CAT sensor to instead of the standard TC. The new FAST XFI has auxillary inputs, the older box I have does not

I will look at some old data logs and see what kind of air temp difference I had in the 2 pc from before the launch until the top of 4th gear.

[Tony Hanna]

...I will look at some old data logs and see what kind of air temp difference I had in the 2 pc from before the launch until the top of 4th gear.

That alone might be enough to prove/disprove the arguement for relocation (seeing if the sensor is heatsoaked to start and then cools or not).
The stock sensor has an exposed element right? If so and my reasoning is sound, then the cool down from being heatsoaked should happen relatively quickly.
I'm curious to hear what you find.

[BadAssPerformance]

The sensor has an exposed element that is isolated by a plastic (read: insulator) cage. I will look for data logs tonight.

[cordes]

Is this for the 2.4? If so, I would just put it in the middle of the intake. Since it is not right above the turbo and exh manifold, I really don't see how it would make a meaningful difference where it is placed.

[BadAssPerformance]

Yes, for the 2.4L...

[Tony Hanna]

The sensor has an exposed element that is isolated by a plastic (read: insulator) cage. I will look for data logs tonight.

That's what I thought. Sounds similar in design to the sensor in my old LT1 car.

[shadow88]

Whatever gains are to be had from a different location are likely neglegable. Nothing I could tell on it's own. You may be reading too far into the changes in sensor readings and the required tweaking of the fast system.

[BadAssPerformance]

Tuning the FAST is a seperate deal.

I am just looking for the most consistant/accurate air temp reading.