2013 Subaru WRX Hatch, Satin Pearl White
Completely Stock internals 9,790 Miles
Roof Rack and Bike Rack externally
91 Octane Shell (CA winter blend I'm assuming)
Pre-Story: About 2 weeks ago I drove my 2013 WRX through a dry sandy valley, when a large bit of wind kicked up the light sand that was piled on the side of the canyon, aside from coating the front of my car in a thin sandy coat I was sure that I sucked up a good bit, When I was washing/waxing the WRX over the weekend I noticed that the air dam on the front bumper had gotten rather muddy from the wash and when I removed it for cleaning I could see the same muddy brown crud coating a large portion of the panel filter. I went down to my local autoparts store and found 4 panels that fit, 3 were paper filters much like the OEM and 1 was a fiberglass filter that required oiling. After reading numerous CIA threads I decided that oiled filters were not for me and decided to go with a dry type panel filter. I found an AEM Dry Panel Filter online for $30 and decided to drop it in.
TLDR: Panel Filter got dirty, Decided to try an AEM Drop in
Approach: I decided to take the most scientific approach I could in replacing the part and testing its effects. I was expecting NO ADDED HORSEPOWER from the intake and without other modifications paying for dyno time isn't really viable at this time. Unfortunately I do not have any aftermarket gauges or an AccessPort to read air fuel ratios (both are on the list of upgrades but not until the suspension and brakes are sorted out) So I determined that the parts I could test without any extra hardware were the noise levels and the fuel economy. That being said I don't know if it had any impact on the horsepower or torque so please don't ask, /rant/ I have read too many threads about some guy that slapped a new intake/filter/duct/vent/ on their WRX and all the sudden it got LOTS more horsepower /rant over/ this is not one of those threads.
Procedure: To test for noise I pulled out my sound tester and placed it 1.5 feet above and 1 foot to the left of my intake air dam. I choose that location because I could rest the tester on my workbench and handle the procedure without extra help. To isolate any chance of vibration adding noise to my tests I used a 1/4 inch Sorbonne noise isolation sheet to rest my tester on. I tested the intake noise level with the dirty factory filter first, after starting and allowing the engine to come to running temps I opened the throttle to 4,500 RPM. The 1st set of tests yielded a total volume of 82 decibels. after allowing the engine to cool enough to get my hand to the side of the air box I removed the box, removed the muddy old filter and test fitted the AEM filter, It only fits in one direction and is a nice tight fit around the air box. after re-assembling the air box and installing it back into its factory location I proceeded to test the volume again. This time with the AEM filter it produced 1 decibel more volume than the factory panel. Before taking it out on the road I unplugged the negative terminal on the battery and held the brake pedal until the lights went dim. this reset should allow the ECU to relearn the new airflow characteristics of the new panel filter. I drove the car to and from work and in the canyons about 120 miles total to allow the ECU to relearn.
Fuel Economy: MPG tests were based on my previous weeks commute to work, my commute has a 14 mile stretch of relatively open highway, I set cruise control at 3,000RPM and reset the fuel economy counter to find a HIGHWAY ONLY fuel economy. with the factory filter I achieved a 27.5 MPG average on the highway stretch of my commute. After I sucked up that dirt I noticed my fuel economy dropped to nearly 23 MPG. after installing the clean AEM panel filter I found that I achieved an even average of 29MPG.
Conclusion: The increased fuel economy was around 5 percent, while that figure seems important it is well within the standard deviation and it is possible that the change may be due to other non-related conditions. The increase in intake noise I am attributing to the difference between a clean and a dirty filter and would for all intensive purposes have little to no effect on heard noise in the cabin. That being said my butt dyno is rather happy with the switch even if it is just knowing that the air filter isn't covered in dry mud. I could swear up and down that the throttle response is better but that again is probably just due to the filter being clean. As far as the savings between a washable dry filter and a factory paper filter, after 20,000 miles the washable filter should prove its worth (assuming I don't replace it with a performance intake before the 30,000 mile mark)
When I get my AP I might stick the dirty old filter in and get some more precise AFR numbers but for now I am enjoying a clean filter.
If you choose to do the same it is highly recommended that you reset the ECU whenever changing intake or exhaust components, even replacing a dirty filter with a clean factory one.
TLDR: installed AEM drop in filter. noise and fuel economy were negligible, cost savings will not be pertinent until 30,000 miles. Reset ECU before driving : )
Completely Stock internals 9,790 Miles
Roof Rack and Bike Rack externally
91 Octane Shell (CA winter blend I'm assuming)
Pre-Story: About 2 weeks ago I drove my 2013 WRX through a dry sandy valley, when a large bit of wind kicked up the light sand that was piled on the side of the canyon, aside from coating the front of my car in a thin sandy coat I was sure that I sucked up a good bit, When I was washing/waxing the WRX over the weekend I noticed that the air dam on the front bumper had gotten rather muddy from the wash and when I removed it for cleaning I could see the same muddy brown crud coating a large portion of the panel filter. I went down to my local autoparts store and found 4 panels that fit, 3 were paper filters much like the OEM and 1 was a fiberglass filter that required oiling. After reading numerous CIA threads I decided that oiled filters were not for me and decided to go with a dry type panel filter. I found an AEM Dry Panel Filter online for $30 and decided to drop it in.
TLDR: Panel Filter got dirty, Decided to try an AEM Drop in
Approach: I decided to take the most scientific approach I could in replacing the part and testing its effects. I was expecting NO ADDED HORSEPOWER from the intake and without other modifications paying for dyno time isn't really viable at this time. Unfortunately I do not have any aftermarket gauges or an AccessPort to read air fuel ratios (both are on the list of upgrades but not until the suspension and brakes are sorted out) So I determined that the parts I could test without any extra hardware were the noise levels and the fuel economy. That being said I don't know if it had any impact on the horsepower or torque so please don't ask, /rant/ I have read too many threads about some guy that slapped a new intake/filter/duct/vent/ on their WRX and all the sudden it got LOTS more horsepower /rant over/ this is not one of those threads.
Procedure: To test for noise I pulled out my sound tester and placed it 1.5 feet above and 1 foot to the left of my intake air dam. I choose that location because I could rest the tester on my workbench and handle the procedure without extra help. To isolate any chance of vibration adding noise to my tests I used a 1/4 inch Sorbonne noise isolation sheet to rest my tester on. I tested the intake noise level with the dirty factory filter first, after starting and allowing the engine to come to running temps I opened the throttle to 4,500 RPM. The 1st set of tests yielded a total volume of 82 decibels. after allowing the engine to cool enough to get my hand to the side of the air box I removed the box, removed the muddy old filter and test fitted the AEM filter, It only fits in one direction and is a nice tight fit around the air box. after re-assembling the air box and installing it back into its factory location I proceeded to test the volume again. This time with the AEM filter it produced 1 decibel more volume than the factory panel. Before taking it out on the road I unplugged the negative terminal on the battery and held the brake pedal until the lights went dim. this reset should allow the ECU to relearn the new airflow characteristics of the new panel filter. I drove the car to and from work and in the canyons about 120 miles total to allow the ECU to relearn.
Fuel Economy: MPG tests were based on my previous weeks commute to work, my commute has a 14 mile stretch of relatively open highway, I set cruise control at 3,000RPM and reset the fuel economy counter to find a HIGHWAY ONLY fuel economy. with the factory filter I achieved a 27.5 MPG average on the highway stretch of my commute. After I sucked up that dirt I noticed my fuel economy dropped to nearly 23 MPG. after installing the clean AEM panel filter I found that I achieved an even average of 29MPG.
Conclusion: The increased fuel economy was around 5 percent, while that figure seems important it is well within the standard deviation and it is possible that the change may be due to other non-related conditions. The increase in intake noise I am attributing to the difference between a clean and a dirty filter and would for all intensive purposes have little to no effect on heard noise in the cabin. That being said my butt dyno is rather happy with the switch even if it is just knowing that the air filter isn't covered in dry mud. I could swear up and down that the throttle response is better but that again is probably just due to the filter being clean. As far as the savings between a washable dry filter and a factory paper filter, after 20,000 miles the washable filter should prove its worth (assuming I don't replace it with a performance intake before the 30,000 mile mark)
When I get my AP I might stick the dirty old filter in and get some more precise AFR numbers but for now I am enjoying a clean filter.
If you choose to do the same it is highly recommended that you reset the ECU whenever changing intake or exhaust components, even replacing a dirty filter with a clean factory one.
TLDR: installed AEM drop in filter. noise and fuel economy were negligible, cost savings will not be pertinent until 30,000 miles. Reset ECU before driving : )