The N54 engine has two phases of oil circulation/venting: under boost (high side) and under vacuum (low side). This kit replaces the more-important low side oil vent system with an oil catch can (OCC) and new hoses to direct oil vapor to the intake instead of through the cylinder head. In addition to a more robust venting system this also addresses the main source of oil/carbon on your intake valves! This is a complete kit, ready to install - no guesswork!
The low side system works on low pressure or vacuum (any time you're not using boost) - idling, light acceleration, getting off the throttle, etc. The factory system is self-contained in the valve cover and cylinder head. Cyclone chambers in the valve cover swirl the oil vapor. Heavier oil droplets are separated from vapor and drain back to the oil pan via the cylinder head. The lighter vapor is routed to the intake valves through a check valve in the valve cover. This kit will evacuate the liquid oil and vapor from the valve cover altogether. Instead of an internal PCV system it becomes an external one. A new hose runs from a connector on the valve cover to an oil catch can. Liquid oil falls to the bottom of the can while vapors are directed to the intake manifold near the throttle body.
An oil catch can is a reservoir that traps liquid oil in the can while allowing the vapor portion to escape. A small amount of liquid oil will accumulate in the can. During your regular engine oil changes - or in between - un-screw the can from the head and dispose of the liquid oil. The catch can is mounted on the driver side using the factory strut brace arm. Note: the hose for this system interferes with the plastic cowl at the base of the windshield and the cowl must be removed. The microfilters in the cowl must be replaced with filters from Burger Motorsports (link
1 x catch can
1 x catch can bracket
2 x 90° low profile -10AN fitting
1 x low side -8AN fitting
1 x vacuum fitting for throttle body
1 x inline check valve
1 x hose from valve cover to OCC
1 x hose from OCC to throttle body fittingImportant Notes:
1. By removing the low side check valve, the low side vent now works all of the time - under vacuum and boost. Your high side boost PCV can remain un-changed (see #2 below) and less oil will find its way into the turbo intake duct at the back of the engine. The high side hose still needs to be maintained as any cracks here will cause a vacuum and oil leak.
2. If you're running high boost (24+psi) or you're building the turbo system to be as leak-free as possible, you may opt to modify the high side with a second OCC.
3. The ports in the cylinder head used to vent vapor should be blocked if you're planning to run more than 24psi of boost. This closes the ports so your new boost does not leak out of the valve cover. A separate port block-off kit is available (link
4. The catch can and hose will not fit with the factory cowl cover. It must be removed and the cowl filters replaced with ones from Burger Motorsports.Notice of Emissions Non-Compliance.
This kit preserves the PCV system and attempts to correct the known weak points in the original design. However, the crankcase vent is part of the engine emissions system and removing, disabling, or altering emissions equipment on a pollution-controlled road vehicle is illegal. Installing devices or software that trick, disable, or modify emissions controls and monitors on a pollution-controlled road vehicle is also illegal. This product is sold only for racing, competition, track, hobby, or other off-road use. It's use is prohibited in any motor vehicle that is subject to emissions inspection or control. Not legal for installation or use in California on any pollution controlled motor vehicle. Not legal for installation or use on any pollution controlled motor vehicle in any state, province, or jurisdiction governed by, or which has adopted, CARB or EPA regulations.
BMW Fitments: 1 Series
E82 / E88 (08-13) > 135i
E82 / E88 (08-13) > 1M (11-12)3 Series
E90 / E91 / E92 / E93 (06-13) > 335i
E90 / E91 / E92 / E93 (06-13) > 335is
E90 / E91 / E92 / E93 (06-13) > 335xi