Obtaining air filter test information from aftermarket manufactures is nearly impossible. Only S&B Filters run their own tests following the recognized industry ISO 5011 test standard while all other manufacturers either don’t run tests or don’t want to share their results to back up their possible misleading or incomplete advertising claims. Some manufacturers will modify ISO 5011 test procedures to enhance their filter performance and then state they test per the standard. Since PSM has a reputation of thoroughly testing their products and sharing this information with customers, we took it upon ourselves to see if we could find independent air filter test results that would be beneficial in determining if any aftermarket filters can be considered superior to the OEM style paper filter.
The most important data contained in an ISO 5011 test for consumers to understand and use is filter efficiency and dust holding capacity of the filter. Filter efficiency is the percentage of dust that was prevented from passing through the filter following ISO 5011 test procedures. For example, 90% filter efficiency means that 90% of the dust (by weight) did not pass through the filter.
Dust holding capacity is the amount of dust (in grams) collected on the air filter to cause the air flow restriction in the filter to increase by 10” water column pressure drop. The higher the grams of dust collected on the filter before reaching the 10” pressure drop, the longer the air filter can be used in real-world driving before causing the filter minder to reach the red zone.
Filter efficiency and dust holding capacity data is presented in the first two columns of the chart. Data came from two independent testing laboratories. One laboratory used course dust and the other used fine dust to determine filter efficiency and dust holding capacity numbers. It is impossible to convert fine dust numbers to course dust values, however, we believe a 0.1 to 1% increase in filter efficiency number is possible and 25 to 50% more dust holding capacity is also possible when filters tested with fine dust are re-tested with course dust.
The third column is PSM’s measured air flow restriction across the filter (recorded in inches of water column pressure drop), taken from a pressure sensor located inside the air box, during real-world testing with the engine at 2900 rpm and full boost. Typically, the lower the pressure drop, the more power the engine will produce in the upper rpm range.
The power data in the last two columns is from PSM’s dynamometer testing of different air filters used inside the PSM cold air modified OEM box. Tests were run with stock fueling and enhanced 80 horsepower fueling. Power gains increased over the OEM paper filter with all air filters when more fuel was added to the engine except for the Amsoil EA air filter.
This chart is loaded with unbiased information. PSM has no filter preference and is only committed to finding and offering their customers the best aftermarket air filter available. The following conclusions can be made from this data.
- From the four different mediums used in air filter construction: paper; cotton gauze, foam and the new dry element; paper has the highest filter efficiency and dust holding capacity. In laymen terms, paper filters allow very little dirt to get into the engine and the filter will hold a lot of dirt before the filter plugs up and lowers engine power. A paper filter will generally have the highest air flow restriction and will limit the power potential of the engine. Paper filters are convenient to dispose.
- One of the gauze air filters (aFe pro-Guard-7) has just as good filter efficiency as the OEM paper filter, but with less dust holding capacity. This means that gauze filters will have to be cleaned 2.5 times for every time a dirty paper filter begins to clog. For example, if OEM filters can last 20,000 miles before the filter minder reaches the red zone, a gauze filter will need to be cleaned every 8,000 miles. Gauze filters are cleaned with a solution, air dried, and then oiled and can be reused indefinitely. Gauze filters have low air flow restriction for getting maximum power from the engine and can typically permit the engine to produce 3 to 4 more horsepower than a paper filter at the higher rpm range.
- Foam type air filters typically have poor filtration efficiency (5 times more dirt passes through these filters compared to an OEM filter) and they will need to be cleaned 1.5 times as often compared to one OEM filter change. Foam filters are cleaned with a solution, air dried, and then oiled and can be reused indefinitely. Foam filters have reasonable low air flow restriction for getting maximum power from the engine.
- Dry element air filters have poor filtration efficiency (4 times more dirt passes these filters compared to an OEM filter) and they will need to be cleaned 6 times as often compared to one OEM filter change. Dry element filters are cleaned by vacuuming or with low air pressure. These filters can be cleaned up to 4 times before being replaced every 100,000 miles. Dry element filters have low air flow restriction, but our testing showed these filters do not allow the engine to make any more power than a paper filter at higher power levels.
Our air filter recommendation to customers will depend on the performance they want from their truck, how they use the truck and how much effort they want to devote into maintaining the air filter.
For customers who are satisfied with the power their stock engine provides and have not installed fuel or air enhancement devices, the OEM type paper air filter is the perfect choice.
For customers who do not work on or maintain their truck themselves, the OEM type paper air filter is the only choice.
For customers who like to make power improvements and maintain their trucks themselves, the gauze type air filter is the best choice. There is absolutely no advantage in using a foam or dry element air filter. We recommend the aFe Pro-Guard 7 filter as the best air filter for our customers. We like the low air flow restriction, the extremely good filter efficiency and the moderate dirt holding capability this filter provides.
For the extreme performance minded customers who are not concerned with filter efficiency, even less air flow restriction gauze filters are available to allow the engine to produce maximum power at very high air flow rates.
Beware that manufacturers typically measure air filter performance on a flow bench and provide a CFM air flow number at a particular pressure drop, usually 1.5” of water column. This number has no real significance to the CFM the air filter can flow. Manufacturer’s air flow numbers are only useful when comparing air filters from different manufacturers PROVIDING you are comparing the identical size air filters and using the same 1.5” pressure drop.
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