All posts by Jeff

Flow Tests

Subaru Airbox MAF Flow testing

A Subaru owner contacted me about putting their airbox on the flowbench to determine how closely the Subaru table for MAF voltages matched with real airflow.

Subaru Airbox on Flowbench
Subaru Airbox on Flowbench

I ran this experiment with the S4 MAF Sensor and did not get a very good match so I was interested to see how things would turn out with the Subaru setup.

Subaru MAF Voltage Table
Subaru MAF Voltage Table

Because the voltage from the MAF sensor is not read by the hardware for measuring the flow bench airflow and pressure drop I needed to hook up a multimeter to the MAF sensor 5V output wire and take manual readings at various airflows.  Although this method is not a precise as it would be if all sensor values were read by the same datalogger, the results were good.

Flow Test Results vs Subaru Table
Flow Test Results vs Subaru Table

Agreement between the Subaru MAF table values and the measurements taken on the flow bench were good.

Turbo Selection

TiAL 605’s Return

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With an eye toward checking out some of the larger turbocharger options, and to see how they stack up against the RS4 K04 based turbo’s I have already tried, I’ve picked up a set of the TiAL 605 version 1 turbochargers along with the various install hoses and fittings.

TiAL 605 v1 Turbochargers
TiAL 605 v1 Turbochargers

They’ll be in line behind the BorgWarner RS6 turbo’s that I have on the shelf, and a set of the current FrankenTurbo F21 design K04 hybrid that is being assembled at FrankenTurbo, so it may be some time before I get these TiAL 605’s installed.

Testing

Hot Air Intake Part 2

For the second part of the test (part one is here) I reattached the accordion to the airbox so that cold air would be directed into the intake.

Cold Air Intake Setup
Cold Air Intake Setup

I made two drives, a morning and afternoon drive.  The morning was the same route as I have taken before, the afternoon drive was shorter due to taking an alternate route that put me on a highway for a short distance rather than sitting in stop and go traffic.

The drives with the ‘cold’ air intake are shown in pink and bright green.

Turbocharger Air Intake Temperature Above Ambient
Turbocharger Air Intake Temperature Above Ambient

The results from these drives are inconclusive, which leads me to believe that the differences are negligible.

Efforts to build a ‘cold air intake’ or worrying about having a ‘hot air intake’ are probably wasted energy.  With the warming that the turbochargers cause to the intake air, even when not in boost, and the cooling effects that the intercoolers offer, these producers of temperature change are much more significant to the temperature of the intake air than where the air is drawn in from.

Some will argue that ‘every little bit counts’, but in looking at the chart above I don’t see where the cold air setup provided any distinct advantage over the hot air setup.