More Shroud Testing

The Intercooler Shroud Test:

I did some additional testing (see here for round one of this series of tests) of the affect of shrouds on the intercooler’s performance after obtaining a set of Evolution Racewerks side mount intercoolers.  I did not purchase the shrouds right away so for a month I drove without shrouds and collected temperature data.

I was interested in determining how much additional cooling the shrouds enabled so that was what I focused on recording data for.  The test scenario would involve driving the car at a slow speed for several minutes and then increasing speed up to a steady 45 to 55 mph which was then maintained for several minutes.  My daily commute involved several minutes of stop and go traffic inbound to a tunnel which facilitated intake air tempertaures becoming quite high.  After passing through a tunnel highway speeds could quickly be reached and maintained for several minutes.  The testing was conducted during the July through August time frame which further helped to accelerate intake air temperatures rising.

Six data sets were collected without the shrouds installed and ten sets of data were collected with the shrouds installed.

The results:

This chart illustrates the drop in temperature from the peak, typically occurring prior to exiting the tunnel and accelerating, to the point in time at which the temperature drop rate began to bottom out, or in other words the intake air temperature was no longer dropping very much relative to the previous rate.

Evolution racewerks shroud test temperature drop

This next chart shows the drop amounts aggregated.  Below the chart is the data table used to create the chart.

Shroud test temperature drop amount

Shroud test temperature amount table

The final chart shows the comparison of the rate of change in temperature accounting for the period of time over which the drop occurred.  If the shrouds allowed the intercoolers to cool off more quickly the rate of change of temperature should be greater.  The point of illustrating the data in this way is to avoid putting too much weight on the overall temperature drop.  It could be argued that with sufficient time a shroud-less intercooler could reach the same steady state temperature as as shrouded intercooler, but it would be more desirable to cool the intercooler quickly, this result factors in the time it takes to cool the intake air.

Shroud test cooling rate

Again, the table of results used to create the chart is also shown.

Shroud test drop rate table


The affect of the shrouds on cooling the intake air temperatures in this scenario appears minimal.  Oddly enough, the median values for the amount of temperature drop, and also the rate of temperature drop, were greater without the shrouds in place.  Conversely, the maximum readings for temperature drop and temperature drop rate were recorded with shrouds installed.

It is hard to write-off shrouds as not worth having when they’re in wide use on many vehicles and the principle behind how they function is sound.  So why the lack of difference in these tests?  One explanation could be that the test is recording intake air temperatures which is not a direct reading of the intercooler core temperature.  If the intercooler core temperature had been measured it’s possible it would have shown more of a difference between the two cases.

Another possibility has to do with the size of this particular intercooler core.  It is a very large intercooler and occupies most of the space available to it.  There is little space for air to pass around the core so the air would flow through the core whether the shrouds were in place or not.

Finally, this test just looked at one specific situation and there could be others where the addition of the shroud caused more of a difference in comparison to the shroud-less case.


In case two test aren’t enough… read on for even more shroud testing with AMD’s intercoolers.

Audi B5 S4