Understanding the Role of a Catch Can in Engine Performance

Modern engines, particularly those with direct injection, are prone to carbon buildup on the intake valves. A catch can intercepts oil vapors and blow-by gases from the crankcase ventilation system before they enter the intake manifold. This simple device helps keep intake tracts cleaner, reduces the risk of detonation, and can extend the life of internal components. For enthusiasts in Nashville who push their vehicles hard, upgrading the stock catch can to one with increased oil capacity is a smart move that directly addresses the demands of daily driving and high-performance use.

The standard catch cans supplied with many aftermarket kits often hold only a few ounces of oil. While adequate for light use, they fill quickly under sustained high RPM or heavy load. An upgraded Nashville catch can with a larger reservoir means fewer empty intervals and more consistent protection for your engine.

What Makes the Nashville Catch Can Different?

The term “Nashville catch can” often refers to a popular style of aftermarket oil separator that is both robust and customizable. These cans are typically constructed from aluminum or stainless steel, with an internal design that promotes effective oil separation. The key features include:

  • Large internal volume – often ranging from 500 ml to 1,000 ml, allowing for extended service intervals.
  • Replaceable filter media or baffle elements – mesh screens, stainless steel wool, or cyclonic separators that trap oil droplets while letting air pass.
  • AN fittings – many Nashville catch cans come with -10 or -12 AN ports, making them compatible with high-flow hose setups.
  • Drain valve – a petcock or quick-drain fitting that simplifies emptying without removing the can.

Unlike generic catch cans, the Nashville design emphasizes ease of mounting and serviceability. It was developed with input from local shops that see a wide range of builds, from naturally aspirated V8s to turbocharged four-cylinders. Understanding these specifics helps you choose the right can for your application.

Why You Should Upgrade to a Larger Capacity Catch Can

Reduce Frequent Emptying

If you track your car or regularly drive in stop-and-go traffic, the oil vapor accumulation can be surprising. A small catch can may need emptying every 200–300 miles, which becomes a chore. A larger Nashville catch can with increased capacity can easily go 1,000–2,000 miles between drains, especially when paired with high-flow breather setups.

Improve Separation Efficiency

Not all oil separators are equal. Many budget cans use a simple chamber that allows oil to reflow into the intake under vacuum. An upgraded can incorporates internal baffles or a cyclonic pathway that forces oil to drop out of suspension. This means less oil mist reaches the intake, reducing carbon buildup and keeping intercoolers and charge pipes clean.

Better Protection for Forced Induction Engines

Turbocharged and supercharged engines produce higher crankcase pressures. The blow-by gases carry more oil than in naturally aspirated engines. A stock catch can may overwhelm, allowing oil to coat the compressor wheel and reduce boost efficiency. A larger capacity can with a high-efficiency separator handles this extra load, protecting both the turbo and the intake system.

Extend Engine Life and Performance

By trapping oil before it mixes with fuel and air, you reduce the risk of detonation caused by oil-induced hot spots. Cleaner intake valves mean better fuel atomization and more consistent combustion. For high-mileage vehicles, this can delay or prevent costly walnut blasting services.

Factors to Consider Before Upgrading Your Nashville Catch Can

Engine Type and Blow-By Volume

Different engines produce different amounts of blow-by. A small displacement four-cylinder engine might only need a 500 ml can, while a large displacement V8 with a turbo kit may require a 1-liter or even 2-liter catch can. Research your vehicle’s typical oil consumption and crankcase vent size to choose the right capacity.

Space Constraints in the Engine Bay

The Nashville catch can’s shape and mounting bracket options vary. Measure the available space near your strut tower, firewall, or inner fender. Some cans are tall and narrow, others short and wide. Make sure the can and its hoses can be routed without rubbing against moving parts or exhaust components.

Hose Routing and Fittings

Upgrading to a larger can often requires larger hoses. Stock PCV hoses are usually 1/2 inch or 3/8 inch ID. For high-flow setups, -10 AN (5/8”) or -12 AN (3/4”) lines are common. Ensure your new can has inlet and outlet ports that match your planned hose size. The routing should be as direct as possible, with minimal bends to prevent oil pooling.

Vent to Atmosphere vs. Recirculating

A recirculating catch can returns the cleaned air to the intake tract, which is necessary to maintain proper engine vacuum and emissions compliance. A vent-to-atmosphere setup releases the air to the engine bay, which is often used in race cars but can cause a rich cabin smell and may not pass emissions. Most Nashville catch cans support both configurations; decide which suits your street or track use.

Step-by-Step Guide to Upgrading Your Nashville Catch Can

1. Choose the Right Larger Capacity Can

Select a Nashville catch can that offers at least double the volume of your current can. Look for models with a transparent sight tube or a drain valve that allows you to check oil level without disassembly. Material matters: 6061 aluminum is lightweight and resistant to corrosion; stainless steel is heavier but more durable. Ensure the can’s internal design matches your goal: a baffle-based can works well for daily driving, while a mesh or cyclonic can is better for high-RPM use.

2. Install an Internal Baffle or Upgrade the Separator

Many aftermarket catch cans come with a simple foam or wire mesh insert that can be replaced with a more efficient stainless steel mesh or a vortex cone. Some Nashville cans offer interchangeable inserts. Remove the existing media, clean the interior, and install the upgrade. This step alone can double the oil retention efficiency.

3. Upgrade the Ventilation Lines

Replace the factory rubber hoses with silicone or braided stainless steel lines. Use metal or nylon fittings to ensure a secure seal. Consider adding a one-way check valve in the line from the valve cover to the catch can to prevent reverse flow during boost. For a recirculating setup, install a dedicated line back to the intake pipe before the turbo or throttle body.

4. Mount the Catch Can Securely

Use the included bracket or fabricate a custom mount that positions the can in a location accessible for emptying. Ideally, mount it on a flat, vibration-free surface such as the inner fender or a strut tower brace. Use rubber isolators to reduce vibration transfer. Make sure the can is oriented upright so the internal baffle works correctly.

5. Connect the Hoses and Test for Leaks

Route the hose from the crankcase vent to the catch can inlet, then from the can outlet to the intake. Use worm drive or T-bolt clamps at each connection. Start the engine and check for vacuum leaks using a smoke machine or soapy water. Listen for hissing sounds that indicate a loose connection. Verify that the catch can is the lowest point in the line so oil drains properly.

6. Monitor and Adjust

After installation, check the catch can after 100 miles to see how much oil it collects. If the can fills quickly, consider a larger unit or adding a second can in series. If it remains dry, the routing may be allowing oil to bypass the separator. Adjust the internal media or check valve direction as needed.

Maintenance and Cleaning of Your Upgraded Catch Can

Even with a larger capacity, periodic maintenance is essential. Follow these best practices:

  • Empty the can every 1,000 to 2,000 miles or when the level reaches 2/3 full. Use a dedicated container and dispose of the oil responsibly.
  • Inspect hoses monthly for cracks, kinks, or oil seepage. Replace silicone hoses if they become brittle from heat.
  • Clean the internal media every 5,000 miles using a solvent like brake cleaner or gasoline. Rinse and dry thoroughly before reinstalling.
  • Replace filter elements annually if they become clogged with sludge. Some mesh inserts can be washed indefinitely, but foam elements degrade over time.
  • Check the drain valve for debris that might prevent proper sealing. A small O-ring failure can cause a constant leak.

Common Mistakes to Avoid When Upgrading

Obfuscating the Crankcase Ventilation

Blocking the PCV system can cause pressure buildup, leading to blown seals and oil leaks. Always maintain a path for crankcase gases to escape. The catch can should not create an obstruction.

Undersized Hoses Restricting Flow

Using the stock hose size on a high-flow catch can defeats the purpose. If your engine produces significant blow-by, upgrade to -10 or -12 AN lines. A 1/2” ID hose may be sufficient for a stock engine, but a modified one needs more capacity.

Improper Mounting Causing Vibration Failures

Mounting the catch can directly to the engine block can transmit severe vibrations that loosen fittings or crack the can. Use rubber grommets or a remote mount on the chassis.

Ignoring the Drain Valve Location

If the drain valve is at the bottom but the can is mounted too low, you may not be able to access it easily. Plan the position so you can empty it without removing the can from the bracket.

Using a Non-Recirculating Setup on a Daily Driver

Venting to atmosphere may cause a strong oil smell inside the cabin, especially with an open-element air filter. It can also fail visual inspections in states with emissions testing. Keep the recirculation path unless you are building a dedicated track car.

Performance Impact of Increased Oil Capacity

While a larger catch can itself does not directly add horsepower, the cumulative benefits show up on the dyno and in long-term engine health. Here’s how:

  • Reduced carbon buildup on intake valves improves airflow and mixture quality, restoring lost power over time.
  • Lower oil consumption means less detonation risk from oil in the combustion chamber.
  • Better crankcase pressure control helps piston rings seal more effectively, increasing cylinder compression.
  • Longer intervals between engine cleaning save money and downtime.

A field test by a well-known tuner showed a 5–10 horsepower gain after installing a high-capacity catch can on a direct injection engine that had moderate carbon buildup. The improvement is gradual as the intake stays clean, but the immediate benefit is the peace of mind that your engine is not ingesting oil vapor.

Conclusion

Upgrading your Nashville catch can for increased oil capacity is one of the most effective and straightforward modifications you can make to protect your engine. By selecting a can with a larger volume, improving the internal separation media, and routing proper hoses, you reduce the frequency of maintenance while enhancing filtration efficiency. Whether you drive a daily commuter, a weekend toy, or a track-prepped machine, the investment pays for itself through extended engine life and consistent performance.

Remember to match the can size to your engine’s blow-by rate, mount it securely, and check it regularly. With a well-executed upgrade, your engine will thank you with cleaner intake valves and fewer unscheduled maintenance sessions. For further reading on catch can theory and installation, consult resources from Mishimoto, Radium Auto, or Racing Perfection. For local advice, reach out to Nashville performance shops that specialize in catch can systems.