IAT Sensor position with JHM Stage 1+ A2W Inter-cooler & Killer Chiller?

[rs4fan]

If this have been discussed before please point me me in the right direction. I couldn’t find anything using the Search option except for Jimmy’s thread where he measured both Pre & Post SC locations with quite significant differences in the results but that was before his A2W Inter-cooler and KC system installations.

So my question, is the current Pre S/Charger location of the IAT Sensor still the best location or are there any beits in moving it Post-S/Charger/Inter-cooler especially when adding a Killer Chiller system to the JHM Stage 1+ A2W setup?

Came across this B8/S4 thread where reference were made to the RS4 IAT Sensor location specifically.
http://audirevolution.net/forum/index.php?topic=2274.msg61780;topicseen#msg61780

Here is what it says… Sounds more like a relocation though… Given they mention OEM sensor I figured it would be a few hundred since anything OEM is priced through the roof…

The factory mass airflow sensor includes an intake air temperature (IAT) probe and is designed to provide the engine control unit (ECU) with air temperature information. Because the RS4 is converted from naturally aspirated to forced induction, the sensor must be relocated to ensure proper IAT measurement. The IAT sensor is absolutely critical for safe, reliable and powerful operation and as such, APR provides an OEM sensor and harness for placement just past the supercharger’s dual internal air-to-water radiators. The included harness allows for simple integration into the OEM wiring harness.

The sensor feeds correct IAT readings to the ECU, which provides closed loop control over various calibration decisions, such as desired ignition advance. This provides safe operation no matter what the condition. During a cold day, with lower supercharger coolant temperature, the ECU will safely increase engine output mainly through ignition. However, under hot conditions, such as a vehicle seeing plenty of track time, the ECU will compensate for these conditions, lowering output slightly to avoid dangerous premature detonation. These compensations result in only attempting to safely achieve the maximum amount of power capable during any given temperature related scenario.

OEM RS4 has the IAT sensor integrated into the MAF sensor. That sensor is pre charger and pre cooler. We use an OEM IAT sensor from another application.

You can’t supercharge one of these engines without having an IAT sensor after charging and cooling. Well, you can, but it would be a stupid mistake.

[justincredible]

I would leave the IAT sensor where it is stock. The car takes readings from more than just the intake air temp. It takes readings from the ambient temp intake air EGT oil temps coolant temps and MAF flow. So having the IAT calculate off the incoming air is going to help balance out with all the other readings. The car will anticipate higher temps before it reaches the combustion chamber from the ambient temps. The fact that you will have lower temps will just help keep the car happier.

From what I have seen from the JHM tunes they seem to use more of the EGT calculation for adjustment of the system than the intake air temps. Using the EGT is better for safety wise and it gives the best level of protection IMHO. From my understanding this is what the newer cars do as well.

You will notice that the JHM tune will react to lower intake temps as the by product will be more efficient charge combustion exit temps.

[rs4fan]

Thanks for clarifying!

[JimmyBones]

I would leave the IAT sensor where it is stock. The car takes readings from more than just the intake air temp. It takes readings from the ambient temp intake air EGT oil temps coolant temps and MAF flow. So having the IAT calculate off the incoming air is going to help balance out with all the other readings. The car will anticipate higher temps before it reaches the combustion chamber from the ambient temps. The fact that you will have lower temps will just help keep the car happier.

From what I have seen from the JHM tunes they seem to use more of the EGT calculation for adjustment of the system than the intake air temps. Using the EGT is better for safety wise and it gives the best level of protection IMHO. From my understanding this is what the newer cars do as well.

You will notice that the JHM tune will react to lower intake temps as the by product will be more efficient charge combustion exit temps.

This is correct.

From the testing that I have done while in dual zone mode with the KC, I saw the ECU pull timing initially as a safety feature and then very quickly give it back along with requesting a lot more.

It will be very interesting to see how my car likes the single zone mode (jokingly nicknamed Thrilla Chilla by a friend of mine) because I had below freezing IATs last night during preliminary testing. My Zadatech gauge can’t read below freezing (0°C/32°F) so I have to use a temp gun to see what the intercooler water temperature is and guess off that. The intercooler water got to between 14-18°F depending on where I tested it at. The brass fittings on top of the intercooler were freezing over!

[rs4fan]

This is correct.

From the testing that I have done while in dual zone mode with the KC, I saw the ECU pull timing initially as a safety feature and then very quickly give it back along with requesting a lot more.

It will be very interesting to see how my car likes the single zone mode (jokingly nicknamed Thrilla Chilla by a friend of mine) because I had below freezing IATs last night during preliminary testing. My Zadatech gauge can’t read below freezing (0°C/32°F) so I have to use a temp gun to see what the intercooler water temperature is and guess off that. The intercooler water got to between 14-18°F depending on where I tested it at. The brass fittings on top of the intercooler were freezing over!

Wow, thats some really low IATs, what was the Ambient temperature at time of the test?

[JimmyBones]

57°F

[rs4fan]

Wow, big drop, can’t wait to get mine installed, should hopefully ship today!

[justincredible]

WOW this is really cool great work jimmyB