Breather Filters

Breather Filters: vent the crankcase, keep the oil mist out of your intake

A crankcase builds pressure as the pistons pump, and that pressure has to go somewhere. Breather filters give it a controlled exit: they let blow-by gases and crankcase pressure escape while a filter element traps the oil mist and dirt that would otherwise coat your engine bay or feed back into the intake tract. On a motor with a vented catch setup, or an engine where you've disconnected the factory PCV routing, a clamp-on or head-mount breather is the piece that keeps the vent clean and open instead of dribbling oil everywhere.

What we stock

There are 55 breather filters and crankcase vent filters in this category right now, spanning 10 brands. K&N Engineering is the deepest line here by a wide margin (29 of the products in the range), followed by Vibrant, Bikers Choice, Uni Filter, HKS, Spectre, AWE Tuning, Radium Engineering, Skunk2 Racing and Kuryakyn. Prices currently run from $28 to $130 for what's in stock, which is a snapshot of live inventory rather than a fixed price.

Coverage is mixed between universal clamp-on filters and application-specific kits. On the universal side you'll find pieces like the K&N 3/4in ID clamp-on crankcase vent filter and the larger K&N 1.375in flange rubber-base vent filter, plus the Radium Engineering 0.75in ID air filter. For specific platforms there's the AWE Tuning S-FLO breather filter for the VW/Audi 2.0T, and Harley-Davidson Big Twin fitment shows up in the Bikers Choice 96-06 Big Twin chrome head breather kit and the Kuryakyn Bluegrass breather kit.

How to choose

The first question is universal versus kit. A clamp-on filter is the cheaper, flexible route - you pick one that matches your hose or fitting ID and slip it on. That's where the low end of the range lives. A full breather kit, like the Harley Big Twin head kits above, includes the mounting hardware for a specific engine and lands toward the top of the price spread. Match the inlet size to what you're actually venting: the K&N clamp-ons list their ID, OD and height so you can spec against your fitting. Only one product in this category carries detailed vehicle fitment data (a Harley-Davidson Big Twin, model years 1996-2006), so for the universal filters, go by dimensions rather than assuming a specific vehicle.

What else you may need

Breather filters live in our Air Intakes section alongside the parts you'd pair them with. If you're also freshening the main intake, look at Replacement Air Filters, Drop In Filters and Panel Filters. Building a full intake means checking Cold Air Intake Kits, and boosted cars often need Intercoolers at the same time.

Fitment and ordering

Not sure a filter's ID matches your fitting or which kit suits your engine? Call fitment help at 813-535-5801 before you buy. All orders ship free, and Affirm and Katapult financing is available at checkout.

Breather Filters: vent the crankcase, keep the oil mist out of your intake

A crankcase builds pressure as the pistons pump, and that pressure has to go somewhere. Breather filters give it a controlled exit: they let blow-by gases and crankcase pressure escape while a filter element traps the oil mist and dirt that would otherwise coat your engine bay or feed back into the intake tract. On a motor with a vented catch setup, or an engine where you've disconnected the factory PCV routing, a clamp-on or head-mount breather is the piece that keeps the vent clean and open instead of dribbling oil everywhere.

What we stock

There are 55 breather filters and crankcase vent filters in this category right now, spanning 10 brands. K&N Engineering is the deepest line here by a wide margin (29 of the products in the range), followed by Vibrant, Bikers Choice, Uni Filter, HKS, Spectre, AWE Tuning, Radium Engineering, Skunk2 Racing and Kuryakyn. Prices currently run from $28 to $130 for what's in stock, which is a snapshot of live inventory rather than a fixed price.

Coverage is mixed between universal clamp-on filters and application-specific kits. On the universal side you'll find pieces like the K&N 3/4in ID clamp-on crankcase vent filter and the larger K&N 1.375in flange rubber-base vent filter, plus the Radium Engineering 0.75in ID air filter. For specific platforms there's the AWE Tuning S-FLO breather filter for the VW/Audi 2.0T, and Harley-Davidson Big Twin fitment shows up in the Bikers Choice 96-06 Big Twin chrome head breather kit and the Kuryakyn Bluegrass breather kit.

How to choose

The first question is universal versus kit. A clamp-on filter is the cheaper, flexible route - you pick one that matches your hose or fitting ID and slip it on. That's where the low end of the range lives. A full breather kit, like the Harley Big Twin head kits above, includes the mounting hardware for a specific engine and lands toward the top of the price spread. Match the inlet size to what you're actually venting: the K&N clamp-ons list their ID, OD and height so you can spec against your fitting. Only one product in this category carries detailed vehicle fitment data (a Harley-Davidson Big Twin, model years 1996-2006), so for the universal filters, go by dimensions rather than assuming a specific vehicle.

What else you may need

Breather filters live in our Air Intakes section alongside the parts you'd pair them with. If you're also freshening the main intake, look at Replacement Air Filters, Drop In Filters and Panel Filters. Building a full intake means checking Cold Air Intake Kits, and boosted cars often need Intercoolers at the same time.

Fitment and ordering

Not sure a filter's ID matches your fitting or which kit suits your engine? Call fitment help at 813-535-5801 before you buy. All orders ship free, and Affirm and Katapult financing is available at checkout.