I've started to notice more OEM-equipped air filters or OEM replacement air filters that glue a foam pre-filter to the bottom (dirty side) of paper panel filters. 2 examples come to mind.
The panel filter used for the Malibu 2.0 LTG (at least on the 2013-2015 2.0 Turbo LTG) and the 2013-up Ford Fusion/Edge/Continental/MKZ 2.0/2.7/3.0 as well as the Ford GT (the supercar, uses a pair of the Fusion filters, one for each turbo). The factory filter for my Fusion Sport (2.7 Ecoboost V6) is just a paper panel filter, but the Motorcraft replacements have a foam pre-filter.
Any ideas on these? I understand turbochargers will draw as much air as they need, but the extra pressure drop on a tuned vehicle could mean less efficiency. On the Malibu's stock filter with the foam, I noticed dirt/leaves starting to collect around the foam at the pleats as if the foam was restricted. There's no easy way to tap out the dirt from the foam.
The panel filter used for the Malibu 2.0 LTG (at least on the 2013-2015 2.0 Turbo LTG) and the 2013-up Ford Fusion/Edge/Continental/MKZ 2.0/2.7/3.0 as well as the Ford GT (the supercar, uses a pair of the Fusion filters, one for each turbo). The factory filter for my Fusion Sport (2.7 Ecoboost V6) is just a paper panel filter, but the Motorcraft replacements have a foam pre-filter.
Any ideas on these? I understand turbochargers will draw as much air as they need, but the extra pressure drop on a tuned vehicle could mean less efficiency. On the Malibu's stock filter with the foam, I noticed dirt/leaves starting to collect around the foam at the pleats as if the foam was restricted. There's no easy way to tap out the dirt from the foam.