After numerous failed efforts over the years to get a hold of a Front Mount Intercooler for flow testing, White Dog Racing sent over their product, which arrived today.

Numerous bungee cords were recruited to hold it above the flow bench for the testing.

The results of the flow test are:

The red bar shows the airflow through the FMIC core without the inlet hump hoses attached.

The pattern when adding the hoses to the inlets has been for the airflow through the core to increase, that was the case with this FMIC as shown by the blue bar

This setup is not very appropriate for comparing with the SMIC’s that I have previously tested since the SMIC’s were tests of a single core, and the SMIC cores were attached straight to the bench, where this FMIC required the elbow silicone coupler to attach to the bench.

The obvious next question after seeing the FMIC result is “how does that compare to the SMIC’s?”  I have included the highest flowing single SMIC that I have tested on the chart, the SRM SMIC, but it should be understood that this comparison between FMIC and SMIC is far from ideal.

All of the turbochargers I have had my hands on lately have been put on the flowbench to have the airflow through the turbine housing recorded.

The most recent B5 S4 suitable turbocharger to show up is a pair of the Audi RS6 K04 turbo’s.  Because in OEM form these will not fit on the 2.7T engine this pair has been modified to work with B5 S4 components.

Unlike with the TTE turbo’s that also showed up with turbo to downpipe studs firmly stuck in the turbine housing, I chose not to pay a shop to remove the studs out of the RS6 turbo’s turbine housing.  Instead I’ve modified the adapter used to attach the turbocharger to the flowbench to accommodate the studs.

Following alteration of the adapter I went through the normal process of testing an article on the flowbench, beginning with a calibration test.   Results of the flow test are shown below:

It is clear that the airflow through the RS6 turbine housing is substantially greater than of that through the RS4 K04 and FrankenTurbo F21 turbochargers.  (The F21, TTE550, and TC Stg1 flowed approximately the same so I have omitted the TTE550 and TC Stg1 data from the chart to make following the lines easier.)

I have found the results on the flow bench to correlate with the exhaust back-pressure readings that I have made on my S4.  That the RS6 K04 turbocharger is able to flow higher than RS4 K04’s comes as no surprise, the magnitude of the increase is the most noteworthy finding from this test.

Today I conducted a flow test comparison of a pair of RS4 MAF’s and an EPL MAF housing.

For some time I’ve wondered how much, if any, restriction the screen on the RS4 MAF housing causes.  A parts car that came through the garage was equipped with a Bosch MAF housing that is the same size as the Bosch RS4 MAF but had a set of screens that are removable.

I decided I would pull the RS4 MAF from my car along with the RS4 airbox top and stick them on the flowbench with the rest of the stock intake to see how the screen affected the airflow through the intake.  I also decided I would retest the EPL MAF housing attached to the stock airbox top as that combination had out-flowed the RS4 MAF and RS4 airbox combination previously.

The results of the flow test are shown below:

Interestingly the removal of the screen from the RS4 MAF provided only a little benefit.  The EPL MAF and stock airbox still provided a little more airflow than the screen-less RS4 MAF and RS4 Airbox top.  All tests were conducted with a stock air filter, modified lower airbox (Darintake modification), and the snorkel attached.

I also have a large K&N cone filter available, so I attached the RS4 MAF to the K&N filter and retested using the RS4 MAF housings.

The results of this test are shown below:

The removal of the screen from the RS4 MAF housing produces a larger increase in airflow with the K&N filter versus the RS4 MAF with the screen in place.

More dramatically, the K&N filter allows for much higher airflow at the test depression of 10″ of H2O.

A couple of things should be noted, first is that a test depression of 10″ of H2O is not very much pressure.  In these tests there is a substantial amount of airflow passing through the intake with minimal pressure drop.  It’s common to test at 28″ of H2O, nearly three times the level this test was conducted at.  This test was performed at 10″ due to a bench limitation of around 600 CFM.

From this test it would seem that the K&N cone filter would be a desired substitute for the stock intake.  What this test does not account for is the potential disruption of airflow over the MAF sensor caused by the cone filter, which could lead to tune problems.

Nor does it show how engine compartment temperatures may alter intake air temperatures with the cone filter.