2015+ Subaru WRX Top Mount Intercooler: Performance Testing

Dyno testing and long-term road testing are where all of this theory meets reality when it comes to the Subaru WRX Top Mount Intercooler. Knowing that the same application of these design techniques resulted in intercoolers that work extremely well for the 04-17 STI and 02-14 WRX, we were confident in our chosen configuration. Our goal was to once again, produce an intercooler that offered excellent cooling capacity without a massive pressure drop. We tested the OEM TMIC, GrimmSpeed TMIC and a leading competitor TMIC in a back to back to back comparison that consisted of driving while everything reached a steady state operating temperature and then three consecutive pulls to redline. The car used in this testing is a GrimmSpeed Stage 2 car on 93oct and was equipped with the same charge pipe for all pulls. Ambient temperatures were around 65F all day. The GrimmSpeed TMIC tested was not thermal dispersant coated.

The chart below shows TMIC efficiency test results. Efficiency is calculated based on the measured inlet and outlet temperatures of the intercooler compared to ambient. If the outlet were to exactly equal to ambient temperature, then efficiency would equal 100%. This isn’t possible, so we strive to get as close as possible. As you can see, the GrimmSpeed and competitor intercoolers outperform the OEM intercooler handily.


The chart below is much less important, but shows the raw temperature data, to give you an idea of how much better performing the GrimmSpeed is compared the OEM TMIC.


The chart below shows the pressure differential between the inlet and outlet of each intercooler. The higher the pressure drop, the more restriction the TMIC causes. This restriction forces the turbo to work harder to build the same amount of boost (which increases heat and is counter-productive), so we want to get keep it as low as possible without sacrificing cooling. You see the the OEM intercooler has the lowest pressure drop, followed by the GrimmSpeed and then the competitor.


One interesting thing that we found is that during the second and third pull, when the car is transitioning from heavy vacuum to full boost, the GrimmSpeed and OEM intercoolers both spooled measurably faster than the competitor TMIC. The GrimmSpeed subaru wrx top mount intercooler has a larger overall volume, so that isn’t the cause. We’re going to continue experimenting to determine the exact reason for this, but it’s likely to be a result of the higher pressure drop and the way that air flows through the intercooler.

The bottom line is that both the GrimmSpeed and competitor unit offer a very nice upgrade from the OEM TMIC as far as efficiency goes. However the GrimmSpeed unit provides a lower pressure drop, and a substantially easier installation. If you have any questions regarding performance or our testing, please don’t hesitate to be in touch with us via phone or email.

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