Catch Can

A catch can is a small tank installed in a race car's engine system that captures oil droplets and other contaminants before they can enter the engine's air intake, helping keep the engine clean and running efficiently.

In motorsport, engines work much harder than regular street cars, which creates more pressure inside the engine block. This pressure pushes oil vapor, unburned fuel, and moisture through the engine's ventilation system. Without a catch can, these contaminants would flow directly back into the engine's air intake, where they can cause problems.

The catch can works like a simple filter. It sits between the engine's breather system and the air intake, intercepting the contaminated air as it flows through. Inside the catch can, oil droplets and other particles condense and settle at the bottom of the tank, while cleaner air continues to the engine's intake system.

This device is especially important for turbocharged engines and direct injection engines commonly used in racing. These engines produce more crankcase pressure and don't have the natural cleaning effect that some older engine designs provide. The catch can prevents oil buildup on intake valves and in the intake manifold, which can reduce engine power and efficiency.

Race teams must regularly empty their catch cans, typically checking them between sessions or races. The collected oil and contaminants are drained through a plug at the bottom of the tank. Some catch cans include a sight glass or dipstick to monitor fluid levels without removing the tank.

Many racing series require catch cans for safety and environmental reasons, preventing oil from being released into the atmosphere or onto the track surface. Street car enthusiasts also install aftermarket catch can systems to protect their high-performance engines during track days and spirited driving.