PreTurbo Air Temperature

After relocating the Auber air temperature sensor to a fitting on the turbocharger inlet pipe, a position just forward of where the exhaust manifold and inlet pipe are running parallel and close by one another, I logged the temperatures again.

The point was to try and determine how much of the pre intercooler heating of the intake air is taking place in the inlet pipe that runs alongside the exhaust manifold as well as through the turbocharger.

The chart below shows the results:

Pre turbocharger intake air temperature chart
Comparison of pre versus post turbocharger/exhaust manifold air temperatures

The lines are a bit busy, so I will try to explain what the chart is showing.

The lighter shaded lines represent data that was collected this morning when the ambient temperature was about 66F.  The darker lines represent data collected midday when the ambient temperature had risen to 79F.  The green lines show the respective ambient temperatures in relation to the other temperature readings.

IAT is the temperature of the intake air as reported by the car’s intake air temperature sensor located after the Intercooler inside the Intake Manifold.

CIT is compressor inlet temperature, the intake air temperature before it goes into the turbocharger, and also because of the placement of the sensor the air has not yet passed alongside the exhaust manifold.

COT is the compressor outlet temperature, the temperature of the air after it has exited the turbocharger, but before it passes through the intercooler.

The morning temperature trend is similar to what I recorded yesterday (IAT Problems) and about a week ago when I looked at IC Efficiency.  The temperature exiting the turbocharger steadily rises well above ambient temperatures even when the car is not being driven hard.

The midday data introduces the pre-turbocharger air temperature and shows this value tracking right along with the post intercooler intake air temperature.

While the intake piping and airbox are contributing some to the temperature rise of the intake air, the greatest climb in temperature is taking place within the inlet pipe that runs alongside the exhaust manifold and the turbocharger compressor housing.

What’s next:

I’d like to narrow down further the location where the temperature is being affected greatest.  If I can identify specific locations of great heat addition I can then investigate possible ways to mitigate the heat addition.  If the exhaust manifold is a significant contributor a few easy options would be ceramic coated exhaust manifolds, ceramic coated inlet pipes, and wrapping the inlet pipe with a thermal shield.

If the turbocharger compressor housing is identified as the greatest contributor finding a remedy will be much harder.