Engine Air Filter Testing


R2C tested engine air filters from multiple manufacturers to establish comparative data for the R2C manufactured product. Each filter was identical in size. With the exception of the R2C filter, which was manufactured by R2C using normal production materials and methods of construction, the individual filters were obtained on the open market and were tested to the exact same standards in order to establish the following performance characteristics:

  • Initial efficiency
  • Initial filter restriction
  • Cumulative efficiency
  • Dust holding capacity

The following equipment and test protocol was used to establish the test results: The tests were performed on a SAE J726 air filter test stand located in R2C's test facility by a qualified R2C Laboratory Technician under the supervision of the Laboratory Supervisor and Engineering Manager. Each filter was tested to the ISO 5011 air filter test standard using PTI Fine test dust. Each test was corrected for temperature, humidity and duct barometric pressure. The laboratory is in an environmentally stabilized facility. Air flow for each test was 400 SCFM. The dust feed rate was 0.028 grams/cubic foot of air flow. Dust capacity was measured at a 10" wg increase in filter restriction above the initial restriction. Cumulative efficiency was also established at this point.


Multiples more dust pass through
21.33 times more dust
8.33 times more dust
14.67 times more dust
5 times more dust
5.33 times more dust


Filter Efficiency and Dust Pass Through

Even though efficiency is reported as the percentage of dust a filter collects, true efficiency is more about what is allowed to pass through a filter rather than what is stopped by it. It is the dust passing through a filter that causes engine damage and premature wear and failure.

When looking at collection efficiency, it is easy to overlook the differences in the volume of dust going through a filter of 99% efficiency versus a filter that's 99.5% efficient. The 0.5% difference seems insignificant until you realize that the 99% filter allows 2 times more dust to pass through than the 99.5% filter.

The data above illustrates the performance of popular filters that were tested and the increase in dust volumes they allow.

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