What Is a Catch Can?

A catch can, also known as an oil catch can or crankcase ventilation catch can, is a simple yet effective device installed in the crankcase ventilation system of an internal combustion engine. Its primary purpose is to separate and capture oil vapors, fuel droplets, moisture, and other contaminants that are normally recirculated from the crankcase back into the engine’s intake system. In modern vehicles, the positive crankcase ventilation (PCV) system routes these gases back into the intake to be burned, reducing emissions. However, this process also introduces unwanted oil mist and carbon deposits into the intake valves, intercooler, and turbocharger components, which can degrade performance over time.

A catch can interrupts this recirculation line, allowing the vapors to cool and condense inside a sealed container. The heavier oil and contaminants fall to the bottom of the can, while the cleaner air and lighter gases continue back to the intake. This separation keeps the intake system cleaner and reduces the amount of oil that reaches the combustion chamber. For high-performance cars, where engines operate under higher RPMs and boost pressures, the amount of blow-by gases increases dramatically, making a catch can an essential upgrade for maintaining engine health.

Most catch cans are constructed from aluminum or stainless steel and include a baffle system or a filter medium (such as steel wool) to improve separation efficiency. They typically have an inlet and outlet port, a drain valve or removable bottom for emptying collected fluids, and a sight tube or dipstick to check fluid levels. There are two main types: closed-loop systems that recirculate the cleaned air back to the intake and open-vent systems that release it to the atmosphere (common in race cars where emissions regulations are not a concern). For street-driven high-performance cars in Nashville, a closed-loop system is recommended to stay compliant with local laws while still gaining the benefits.

How Catch Cans Improve Engine Efficiency

Preventing Oil Contamination of Intake Components

When oil vapors are allowed to recirculate unchecked, they coat the intake manifold, throttle body, and intake valves with a sticky, carbon-rich film. This buildup reduces airflow, disrupts the air-fuel mixture, and can cause hot spots that lead to pre-ignition or knock. In direct-injection engines, which are common in modern high-performance cars (e.g., Ford EcoBoost, GM LTG, and many turbocharged imports), the lack of fuel washing over the intake valves means carbon deposits accumulate rapidly. A catch can dramatically reduces this buildup, helping maintain the designed airflow and combustion efficiency. Over time, this translates to better throttle response, consistent power delivery, and improved fuel economy.

Reducing Knock and Pre-Ignition Risk

Oil vapor in the intake charge lowers the effective octane rating of the fuel-air mixture. When oil droplets enter the combustion chamber, they can ignite unpredictably, causing knock or detonation. This is particularly dangerous in high-performance engines running high boost pressures or aggressive timing. By removing the majority of oil vapor, a catch can helps maintain a stable, predictable combustion environment. Engine management systems can then operate closer to optimal timing without pulling back due to knock, resulting in higher power output and better efficiency. Many tuners report that after installing a catch can, they can increase boost or advance timing slightly because the knock margin improves.

Maintaining Turbocharger and Intercooler Performance

In turbocharged high-performance cars, oil vapor carried through the PCV system can coat the inside of the intercooler, reducing its heat-exchange efficiency. A fouled intercooler raises intake air temperatures, which directly reduces power and increases the risk of detonation. Similarly, oil deposits on the compressor wheel of the turbo can unbalance the rotating assembly and reduce boost efficiency. By trapping these contaminants before they reach the turbo and intercooler, a catch can helps these components operate at peak effectiveness. For Nashville drivers who frequently accelerate hard on the highway or participate in track days, this maintenance of thermal and mechanical efficiency is critical for consistent performance.

Improving Oil Life and Reducing Engine Wear

The oil vapors that are captured by the catch can are oil that never gets returned to the crankcase. In engines without a catch can, this oil is either burned in the combustion chamber or deposited on intake surfaces. Burning oil increases the rate of oil consumption and can lead to low oil levels between changes, increasing wear. Additionally, the contaminants collected in the catch can include acidic compounds and moisture that would otherwise be recirculated and potentially accelerate oil degradation. By keeping these byproducts out of the oil sump, the engine oil stays cleaner longer, providing better lubrication for bearings, piston rings, and valvetrain components. This directly contributes to longer engine life and sustained peak efficiency.

Benefits of Catch Cans Specifically for Nashville High-Performance Cars

Nashville is home to a vibrant car culture, with numerous performance shops, car clubs, and events such as the Nashville Auto Show, Music City Car Club meets, and track days at the Nashville Super Speedway and the nearby Autobahn Country Club. High-performance cars here range from domestic muscle cars like Dodge Challenger Hellcats and Ford Mustang GTs to turbocharged imports like Subaru WRX STIs, Nissan GT-Rs, and European exotics. All of these vehicles can benefit from a catch can, but the local driving conditions make it especially valuable.

Dealing with Nashville’s Humidity and Temperature Variations

Nashville experiences high humidity and significant temperature swings between seasons. Humid air drawn into the engine increases the moisture content in crankcase vapors. When these vapors are recirculated without a catch can, water vapor can condense inside the intake system, leading to corrosion and sludge formation. A catch can captures much of this moisture, protecting the intake and oil from contamination. This is particularly important for cars that are driven only on weekends or stored for periods, as moisture can cause rust and varnish deposits that degrade efficiency over time.

Stop-and-Go Traffic vs. High-Speed Highway Cruising

Nashville drivers often face heavy stop-and-go traffic on interstates like I-40 and I-65, especially during rush hours. In this type of driving, engine speeds stay low, and the PCV system may not flow enough to properly purge vapors, leading to increased oil dilution and buildup. On the other hand, when those same drivers take their high-performance cars out for spirited drives on winding roads or open highways, the engine sees high RPM and boost, generating more blow-by. A catch can works effectively across both operating conditions, collecting oil and contaminants that would otherwise settle in the intake. This versatility makes it an ideal upgrade for Nashville’s mixed driving environment.

Supporting Performance Modifications

Many Nashville car enthusiasts run tuned engines with increased boost pressure, upgraded turbos, aftermarket intakes, and high-flow exhaust systems. These modifications increase crankcase pressure and blow-by volume. The factory PCV system is often inadequate under these conditions, leading to oil leaks, excessive smoke, and performance degradation. A properly sized catch can with good baffling can handle the increased flow, keeping the intake clean and allowing the modifications to deliver their intended gains. For example, a tuned 2018 Camaro SS with a catch can installed showed a 12 horsepower increase on the dyno compared to the same car without a catch can, simply because the intake was free of oil deposits and the air-fuel ratio was more consistent.

Environmental and Maintenance Benefits

Catch cans also reduce the amount of oil and other pollutants that are burned and expelled through the exhaust. Although the effect on tailpipe emissions is small on an individual vehicle, it contributes to lower overall emissions for Nashville’s fleet. Additionally, by keeping the intake valves and combustion chambers cleaner, the engine runs more efficiently, which can improve fuel economy. For high-performance car owners who drive their cars daily, this means fewer trips to the gas station and reduced maintenance costs associated with carbon cleaning services, such as walnut blasting, which can cost hundreds of dollars and require significant labor.

Installation and Maintenance of Catch Cans

Choosing the Right Catch Can

Not all catch cans are created equal. For high-performance applications, look for a catch can with a large internal volume, good baffling (either internal plates or filter media), and a drain valve or easy-to-remove bottom. Some popular brands for Nashville performance cars include Radium Engineering, Mishimoto, and Saikou Michi. Be sure to select a can that is compatible with your specific engine’s PCV system layout. Universal fit cans can work, but vehicle-specific kits often include pre-cut hoses and mounting brackets that simplify installation.

Installation Process

Installing a catch can is a straightforward job that many DIY enthusiasts can handle in an afternoon. The basic steps are:

  1. Locate the PCV valve and the fresh air intake line on your engine. Refer to the factory service manual to identify the correct hoses.
  2. Disconnect the hose that runs from the crankcase or valve cover to the intake tube. This is typically the hose responsible for recirculating blow-by gases.
  3. Mount the catch can in a suitable location using brackets or zip ties. It should be upright, accessible for draining, and away from heat sources or moving parts.
  4. Connect the inlet port of the catch can to the crankcase/valve cover side using the provided hose. Then connect the outlet port to the intake tube side. Ensure all connections are secure and leak-free.
  5. If your car has a separate PCV valve or a second vent port (common on V8 engines), you may need a second catch can or a dual-port model. Follow the manufacturer’s guidelines for your specific setup.
  6. After installation, start the engine and check for vacuum leaks, unusual noises, or any signs of oil leaking from the connections. Drive the car and then inspect the catch can for collected fluid.

Maintenance Best Practices

Regular maintenance is crucial for the catch can to function effectively. The collected oil and condensate should be emptied every 1,000 to 3,000 miles, depending on driving conditions and engine modifications. Cars driven hard at the track may need emptying after every event. Many catch cans have a clear sight tube so you can see the fluid level at a glance. When emptying, dispose of the oil properly at a recycling center. Periodically inspect the interior of the catch can for excessive sludge or blockages; if using a filter medium, replace it as recommended by the manufacturer. Also check hoses for cracking or hardening, as heat and oil can degrade them over time. Keeping the system clean ensures that the catch can continues to improve engine efficiency without adding restriction.

Common Myths and Misconceptions About Catch Cans

Myth: Catch cans are only for race cars.

While it’s true that race cars often use open-vent catch cans to manage high blow-by, street-driven high-performance cars benefit just as much from closed-loop systems. In fact, daily-driven performance cars may see even greater benefits because they accumulate more carbon deposits from extended idling and part-throttle driving.

Myth: Catch cans void the warranty.

Installing a catch can that cuts into a factory hose may technically modify the emissions system, which some dealers could use to deny warranty claims related to engine damage. However, many aftermarket catch can kits are designed to be reversible and do not require permanent modifications. If you are concerned about warranty, look for a “no-cut” installation kit that uses quick-connect fittings or simply keep the OEM parts to reinstall if needed. After the warranty period, a catch can is a safe and effective upgrade.

Myth: Catch cans cause increased oil consumption.

On the contrary, catch cans reduce the amount of oil that is burned in the engine, which can actually lower oil consumption. The oil captured in the can is not being returned to the crankcase, but if the can is emptied regularly, the total oil consumption should remain stable or decrease. The small amount of oil collected is negligible compared to what would have been burned without a catch can.

Myth: All catch cans are the same.

Quality varies widely. Cheap catch cans often have poor internal baffling, allowing oil to pass through and negate the benefits. For high-performance engines, invest in a well-designed catch can from a reputable brand. Look for features like an internal diverter plate, a large condensation chamber, and high-quality O-rings to prevent leaks. A good catch can will pay for itself by extending engine component life and reducing maintenance.

Conclusion

For car enthusiasts in Nashville who demand the best from their high-performance vehicles, a catch can is a proven, cost-effective upgrade that delivers measurable improvements in engine efficiency, reliability, and longevity. By preventing oil contamination of the intake, reducing knock risk, maintaining turbo and intercooler performance, and extending oil life, a catch allows the engine to run cleaner and produce consistent power. Whether you drive a supercharged Mustang on the highway, a turbocharged WRX to the grocery store, or a modified GTR on the track, adding a quality catch can is one of the smartest modifications you can make. Pair it with other basic maintenance and performance upgrades, and you’ll be able to enjoy Nashville’s roads and car events with confidence that your engine is operating at its best.

For more technical details on catch can design and PCV system theory, check out this guide on catch can basics. If you’re looking for a specific kit for your car, Mishimoto offers vehicle-specific options with detailed installation instructions. For Nashville locals, consider attending an event at the Nashville Superspeedway to see how other enthusiasts have set up their cars.