RS4 Intake Manifold Flow Test

Completed flow testing on an unmodified RS4 intake manifold.

RS4 Intake manifold on flowbench

One observation while testing the RS4 intake manifold was how much further up inside the runner the fuel injector sits.  Comparing the placement to that of the S4 intake manifold the RS4 fuel injector sits approximately 40mm from the exit where on the S4 intake manifold the fuel injector is approximately 22mm from the runner exit.

RS4 fuel injector placementNot too surprisingly the RS4 intake manifold flowed on average 27% more than the S4 intake manifold based on measurements taken at 10″ of H2O.

RS4 Intake manifold flow numbers

One interesting result from the topmost picture is the airflow velocity out of the lowermost runners of the RS4 intake manifold.  With the larger runner, as compared to the S4 intake manifold, the air velocity is even lower for a given depression.  The lower right runner had airflow velocity (feet per second) in the single digit range.

 

Raining intake manifolds

When it rains…

I went from zero intake manifolds to test out to having two RS4 intake manifolds waiting to go on the bench, each needing a different adapter from the one I’d made up for the stock intake manifold, so back to work making adapters.

RS4 intake manifold lineup

More pictures from different angles to come as I get closer to testing the different intake manifolds out on the flow bench.

Flowbench adapter

Starting to build an adapter for the OEM RS4 intake manifold.

 

Exhaust velocity probe

After acquiring a velocity probe designed for measuring exhaust direction airflow I went and put the stock intake manifold back on the flow bench to measure the air velocity at the various runner outlets while all were open and a steady air stream was pushed through the manifold.  Similar to the last time, the first two runners showed the lowest air velocities.

Intake manifold with viewport

Considering the shape of the IM plenum, the increasing velocity recorded by the velocity probe at the rearward runners is not surprising.

New for this test, and something that I will use for future evaluations, is a viewport that will allow me to precisely place the probe tip along the centerline of the intake manifold plenum.