Oil Catch Cans: Why Every Performance Engine Needs One

An oil catch can is one of the least glamorous modifications in performance motoring - and one of the most useful. If your car doesn't have one, it's very likely that oily, partially combusted blow-by gases are recirculating through your intake manifold and onto your intake valves right now. Over time, this builds carbon deposits on the valves, degrades intake manifold surfaces, and affects combustion efficiency. A catch can stops it.

What Blow-By Is and Why It's a Problem

During the combustion cycle, small amounts of combustion gas escape past the piston rings into the crankcase - this is called blow-by. All engines produce it, and the PCV (Positive Crankcase Ventilation) system is designed to deal with it by routing these crankcase gases back into the intake tract to be re-combusted, rather than venting them to atmosphere.

The problem is that these gases carry oil vapour and combustion byproducts with them. On direct injection engines (like most modern turbocharged units and the LS family in VE/VF Commodores), there's no fuel being injected at the intake valve to help wash it clean. The result is carbon build-up on the back of intake valves that progressively restricts airflow and affects performance.

What a Catch Can Does

An oil catch can sits in the PCV line between the crankcase and the intake manifold. As blow-by gases pass through, the can's internals - typically a baffle or filter element - separate the oil vapour and liquid contaminants from the gases. The clean gas continues to the intake; the oil collects in the catch can and is periodically drained. The result is a significant reduction in the amount of oily residue reaching your intake valves and manifold.

Aeroflow Catch Can Range

Aeroflow Performance manufactures a comprehensive range of catch cans in various sizes and configurations, available at BYE Performance. Their units use stainless steel baffling and are available in 200ml through to 500ml capacities to suit different engine displacements and blow-by volumes. For high-output turbocharged engines or supercharged LS applications, a larger-capacity unit is recommended to extend the drain interval.

Aeroflow catch cans are supplied with quality fittings and can be installed using their AN fitting range for a clean, leak-free finish - important in a performance engine bay where appearance and functionality both matter.

Where to Plumb the Catch Can

Most installations intercept the breather line between the rocker cover and the intake manifold. On LS engines with dual rocker cover vents, a two-inlet catch can with a single outlet is the correct setup. The can is typically mounted in a stable, accessible location in the engine bay for easy draining. BYE Performance can install catch cans as part of any service or modification visit.