The latest component to get wrapped is the upper half of the turbo inlet hard pipe, this is the section that connects to the Y-pipe coupler hose.  I wrapped this section in the DEI Reflect-A-Gold tape.

At this stage most everything from the inlet snorkel to the turbocharger compressor inlet is now wrapped in some way or another.  The part that isn’t wrapped is the airbox snorkel, and I’ll probably do something with it next.

I went and drove my usual route recording the intake temperatures.  Rather than post up the composite chart, because it is getting very busy, I’m going to post the temperature deltas of the last two and first two recordings that I made.

The morning drive has two fewer data series than the afternoon drive, only going up to 7.  Drive 1 is in the normal configuration that I had prior to doing any of the wrapping.  The 2 series is the same but with the Darintake holes covered.  Series 6 and 7 are with most of the wrapping in place, through to the Y-pipe in 6 and the hard pipe in 7.

The afternoon drive data with similar data series is shown below.

These results show very little difference between the ‘untreated’ inlet piping and the ‘treated’ pipes with all of the wrapping in place.

Continuing down the intake I’ve gone and wrapped up the RS4 Y-Pipe.

It’s quite the beaut now, with Duct Insulation wrapped around the entire thing.

Seeing as how the Y-pipe is an ‘air duct’ applying this material seems proper.  It consists of a foam layer about 3-4 millimeters thick with a reflective coating on one side and adhesive on the other.  The advertised R value for the material is R-3.

Taking the S4 out for my usual drives produced the following results in the morning:

Later in the day I repeated the procedure recording in higher ambient temperatures.

Adding these latest drives into the collection that I’ve got going yields the following charts:

Afternoon drive:

I was hopeful that this extra heat protection would produce some benefit, the Y-pipe sits directly on top of the engine and seems like a good candidate for some insulating material.

There are moments in the drive when the temperature with this latest modification is lower, around approximately 5 degrees F.

Without digging deeper into the data my initial call is that the wrapping did help some.

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.