Category Archives: Testing

Wrapped Y-Pipe Temperatures

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

Foil Wrapped B5 RS4 Y-Pipe
Foil Wrapped B5 RS4 Y-Pipe

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

Duct Insulation
Duct Insulation

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:

Morning Drive with Wrapped Y-Pipe
Morning Drive with Wrapped Y-Pipe

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

Afternoon Drive with Wrapped Y-Pipe
Afternoon Drive with Wrapped Y-Pipe

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

Morning Drive Comparison
Morning Drive Comparison with Wrapped Y-Pipe

Afternoon drive:

Afternoon Wrapped Y-Pipe comparison chart
Afternoon Wrapped Y-Pipe comparison chart

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.

Cruising Turbo Outlet Temperatures

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.

Auber Instruments Air Intake Temperature Sensor
Auber Air Temperature Sensor installed in charge pipe joining turbo and intercooler

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:

Morning Drive Temperature with Turbocharger Outlet Temps
Morning Drive Temperature with Turbocharger Outlet Temps

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.

SPP A-Pillar Gauge Pod
SPP A-Pillar Gauge Pod

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

Afternoon Drive recording Turbo Outlet Temperatures
Afternoon Drive recording Turbo Outlet Temperatures

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.

Gold Wrapped MAF Sensor Housing

Continuing down the intake, I wrapped the MAF sensor housing with the DEI Gold tape, and put a double layer of heavy duty aluminum foil around the accordion hose.

DEI Gold Wrapped MAF Sensor Housing
DEI Gold Wrapped MAF Sensor Housing
Kingsford Aluminum Foil

One theory has postulated that the location of the MAF sensor housing above the passenger side turbocharger means that “all of the hot air coming from the turbocharger will rise and heat up the MAF sensor housing”.

Perhaps, this step was an attempt to see if wrapping the MAF sensor housing and accordion hose would lead to a temperature reduction at the inlet pipe.

Here’s the morning drive results:

Morning Drive with MAF Sensor Housing Gold Wrapped
Morning Drive with MAF Sensor Housing Gold Wrapped

The dark blue line is the data with the MAF sensor housing wrapped in the DEI Gold tape.  It (Gold tape and Aluminum foil) does not appear to have significantly altered the temperature profile.

In the afternoon the results were:

Afternoon Drive with DEI Gold tape on MAF Sensor housing
Afternoon Drive with DEI Gold tape on MAF Sensor housing

Again there was nothing notable in the results to indicate that the DEI Gold tape applied to the MAF Sensor housing led to a reduction in the inlet air temperatures.  This drive took place on one of the hottest days yet, thus the temperature curve is higher than most others.