I reattached the temperature sensor that I use to record the compressor outlet temperatures.  Combined with the readings from the inlet temperature sensor these two pieces of data illustrate the rise in intake air temperature that occurs as the air passes through the turbocharger compressor.

This sensor is located in the hard pipe that joins the turbocharger compressor outlet to the intercooler intake end tank.

As I have done for the past couple of weeks I logged the temperature of the intake air as it passes through the car’s intake system.  The results from the morning drive are shown below:

Tu_In is the temperature of the air entering the turbocharger, shown with the red line.  Tu_Out, the dark green line, is the temperature of the air as it leaves the turbocharger compressor housing.  The light green line is the ambient air temperature.  Interestingly the turbocharger outlet temperature goes well above the intake air temperature at the Intake Manifold within about 2 minutes of starting the engine.

What is also noteworthy is that at no time did I push the turbo’s to produce boost, the spikes occurred while the intake manifold was still under a small amount of vacuum, as displayed by my A-pillar mounted boost gauge.

I recorded temperatures again during  an afternoon drive, though the route was different from what I have previously taken.

I briefly pushed the turbochargers to produce boost of approximately 18 psi during the end part of the drive.  This boost event only lasted around 1-2 seconds.  I would have expected to see compressor outlet temperatures around 250 degF or greater if sustained boost around 20-22 psi had been achieved for 3-4 seconds.

One of the most notable aspects of these charts is the delta between the green, compressor outlet, and red, compressor inlet, temperatures.  This is the rise in intake air temperature as the air passes through the turbocharger compressor, a large change results even when out of boost and only cruising.