Catch Tank

A catch tank is a safety container fitted to race cars that collects oil vapors, excess fluids, and other contaminants that escape from the engine or gearbox, preventing these liquids from spilling onto the racetrack where they could cause dangerous accidents.

In a regular road car, engine vapors are usually recycled back into the intake system or vented harmlessly. However, in high-performance racing engines that operate under extreme conditions, much more oil vapor and fluid mist is produced. Without a catch tank, these fluids could drip onto the track surface, creating slippery conditions that put all drivers at risk.

The catch tank works by intercepting fluids before they can escape. It connects to breather outlets from the engine's crankcase, oil tank, or gearbox. As hot gases and vapors pass through the catch tank, they cool down, causing oil droplets, unburnt fuel, and water vapor to condense and collect in the container rather than being released.

Most racing organizations require catch tanks as mandatory safety equipment. The FIA, which governs international motorsport, specifies minimum capacities based on engine size—typically 2 liters for engines up to 2000cc and 3 liters for larger engines. These regulations ensure that tanks are large enough to contain fluids throughout an entire race.

Beyond track safety, oil catch cans provide performance benefits. They prevent oil from entering the engine's intake system, which can coat intake valves and reduce engine efficiency over time. By keeping the intake clean, catch tanks help engines breathe properly and maintain consistent power output throughout a race.

A typical catch tank includes several key features. A transparent sight glass allows mechanics to monitor fluid levels at a glance. A drain plug at the bottom makes it easy to empty collected fluids between sessions. Many also include internal baffles or filter elements that help separate oil from air more effectively, and a breather cap that allows air to escape while containing liquids.

There are two main types of catch tank systems. Open systems vent filtered air to the atmosphere after capturing liquids, while closed systems recirculate clean air back into the engine's ventilation system. The choice depends on racing regulations and specific engine requirements.

Installing a catch tank requires placing it between the engine breather outlet and wherever that breather would normally vent. In racing applications, the tank must be securely mounted and easily accessible for inspection and draining. Regular emptying is essential, as an overfilled catch tank defeats its purpose and may cause fluid to escape.