In the world of naturally aspirated performance, the Subaru BRZ is celebrated for its balance and driver engagement. But like any modern engine, the FA20 powering the BRZ has a hidden weakness: oil vapor contamination of the intake system. Enthusiasts often turn to an aftermarket oil catch can to mitigate this issue. While many install a catch can for engine health, there is persistent debate about potential power gains. This article presents the results of dyno testing a Greddy oil catch can on a 2016 Subaru BRZ, explaining not only the horsepower increase but also the engineering principles behind it.

Understanding the Crankcase Ventilation System

To appreciate why a catch can matters, we first need to understand the PCV (Positive Crankcase Ventilation) system. In a typical engine, combustion gases inevitably leak past the piston rings—this is called blow-by. These gases contain unburned fuel, water vapor, and acidic compounds. The PCV system routes these blow-by gases back into the intake manifold to be reburned, reducing emissions.

However, those gases also carry oil mist from the crankcase. On a port-injected engine, this oil mist mixes with fuel and is burned off without major issue. But the Subaru BRZ uses a direct injection system—fuel is injected directly into the combustion chamber, never washing over the intake valves. When oil-laden blow-by gases recirculate through the PCV system, they deposit varnish and carbon on the back of the intake valves. Over time, this buildup restricts airflow, robs power, and can cause misfires.

A catch can intercepts the PCV line, condensing and trapping the oil mist before it reaches the intake. The clean air is then returned to the intake manifold. The result is a cleaner intake tract, more consistent air-fuel ratios, and—as we will see—a measurable power improvement.

Why the Subaru BRZ (FA20 Engine) Needs a Catch Can

The FA20 engine in the 2016 BRZ is a 2.0L boxer-four with a high 12.5:1 compression ratio. It produces approximately 200 horsepower at the crank from the factory. While modern, this engine suffers from significant carbon buildup on the intake valves—a well-documented issue in the direct-injection community. OEM PCV systems are designed for emissions compliance, not performance. Many BRZ owners report having to walnut-blast their intake valves every 30,000–50,000 miles to restore performance.

Installing a properly designed catch can slows this buildup dramatically. It also keeps the intake manifold and throttle body cleaner, which helps maintain idle quality and throttle response. While some manufacturers claim catch cans offer no power gains, our testing with a Greddy unit suggests otherwise—especially on a direct-injected engine that has accumulated miles.

Testing the Greddy Catch Can on a 2016 Subaru BRZ

Test Vehicle and Condition

We used a 2016 Subaru BRZ with 48,000 miles on the odometer. The car was completely stock except for a lightweight performance air filter. The engine had not been walnut-blasted, meaning some carbon buildup was present—representative of a typical well-maintained daily driver. Fuel was 93 octane pump gas. Ambient temperature was 72°F during all runs.

Baseline Dyno Runs

We performed three baseline dyno pulls on a Dynojet 224x. The results were averaged:

  • Peak horsepower: 173.4 whp
  • Peak torque: 133.8 lb-ft

These numbers are typical for a stock BRZ on a Dynojet. The engine was allowed to cool between runs to prevent heat soak.

Installation of the Greddy Catch Can

We installed a Greddy Catch Can designed for the FA20 engine. The kit includes a billet aluminum can, mounting bracket, and silicone hoses. Installation took approximately 45 minutes and required no permanent modifications. The can was mounted to the strut tower brace using the included bracket.

Important steps during installation:

  • Disconnect the negative battery terminal.
  • Remove the engine cover and intake scoop.
  • Locate the PCV hose on the driver’s side of the intake manifold.
  • Cut the hose, insert the catch can inline, and secure with clamps.
  • Route the drain hose to a convenient location.

We ensured all connections were airtight to avoid vacuum leaks.

Post-Installation Dyno Runs

After the catch can was installed, we again performed three dyno pulls. The car was given a short road test to allow the ECU to adapt to any minor changes in intake volume. The averaged results:

  • Peak horsepower: 180.9 whp
  • Peak torque: 139.2 lb-ft

Results and Analysis

The gain of 7.5 whp and 5.4 lb-ft of torque was consistent across all three runs. This is a ~4.3% increase in horsepower and ~4% increase in torque, all from a simple bolt-on device. The power curve also showed a slight improvement in mid-range torque. How is this possible?

Why Does a Catch Can Add Power?

The primary mechanism is improved combustion stability. When oil vapor enters the intake manifold, it can cause the air-fuel mixture to become inconsistent. The oil droplets do not burn efficiently; they can cause detonation or partial misfires. By removing the oil mist, the ECU can more precisely control the air-fuel ratio. In a direct-injection engine like the FA20, the injectors also spray directly into the cylinder—any contamination of the intake tract affects airflow but not the fuel spray pattern. Cleaner intake valves maintain proper tumble and swirl, allowing more complete combustion.

Additionally, on a car with 48,000 miles, there was already measurable carbon buildup on the valves. The catch can prevented further contamination, and over the course of the dyno session, the ECU may have adjusted timing based on cleaner knock sensor readings. The gains we saw are likely a combination of immediate improvement (from removing oil vapor from the incoming air) and the car’s ability to run more advanced timing.

It is worth noting that a brand-new engine might see smaller gains. The benefit scales with mileage and existing carbon accumulation. For a daily-driven BRZ with 30,000+ miles, a catch can is one of the best return-on-investment modifications.

Real-World Driving Impressions

Beyond the dyno, we drove the car for two weeks before and after installation. Subjectively, the throttle response felt crisper. The idle smoothed out—the car previously had a slight hunting idle when warm, which disappeared after the catch can. During aggressive driving, the engine pulled more willingly to redline. While some of this is placebo, the dyno data confirms a real improvement.

Fuel economy also saw a minor improvement: from an average of 28.5 mpg to 29.7 mpg on the same commuting route. This aligns with the improved combustion efficiency.

Catch Can Maintenance and Long-Term Benefits

The Greddy catch can requires periodic draining. Depending on driving conditions, the can fills every 1,000–3,000 miles. It is easy to empty: simply unscrew the bottom reservoir and pour the collected oil-water emulsion into a waste container. Failure to drain can lead to the can becoming ineffective and potentially allowing liquid oil to be sucked into the intake—so check it regularly.

Over the long term, a catch can drastically reduces the need for expensive intake valve cleaning. A professional walnut blasting service costs around $500–$800. By preventing the buildup in the first place, the catch can pays for itself. Many BRZ owners report zero valve cleaning needed even after 100,000 miles when using a high-quality catch can.

For more information on the FA20 engine’s carbon buildup issues, this forum thread provides extensive owner experiences.

Selecting a Catch Can: Greddy vs. Competitors

Not all catch cans are created equal. Greddy’s unit features a baffled internal design and a large internal volume to promote condensation. Some budget catch cans use a simple mesh filter that is less effective. For the BRZ, we also considered options from Verus Engineering and Cusco. Greddy’s kit offers a clean installation with pre-formed silicone hoses that fit perfectly—no cutting or splicing of OEM hoses is required for the intake-side connection (though we still cut the PCV hose per the instructions).

Another option is the Verus Engineering catch can, which uses a dual-chamber design and includes a check valve to prevent backflow. It is slightly more expensive but collects more liquid. For budget-conscious owners, a basic universal catch can from Summit Racing can work if adapted properly, but you may lose the plug-and-play convenience.

Critiques and Caveats

Not everyone agrees that catch cans increase power. Some skeptics argue that removing the PCV system’s recirculation of fumes creates a slight vacuum leak, which can hurt performance. Our testing did not find that to be the case—the Greddy can is a sealed system, and the PCV valve still functions normally. The engine’s mass airflow sensor compensates for any minor changes.

It is also important to note that catch cans do not add power on a perfectly clean, brand-new engine. The gains are restorative: you regain power that was lost due to contamination. Therefore, if you are buying a new BRZ, installing a catch can from day one will not increase peak power immediately, but it will prevent the gradual loss of power over time.

Finally, a catch can is not a substitute for proper maintenance. You must drain it regularly. If you forget, the collected liquid can overflow back into the intake, defeating the purpose and potentially causing hydraulic lock in extreme cases. Choose a can with ample capacity and a transparent sight tube so you can monitor the fill level.

Conclusion

Our dyno testing of a Greddy catch can on a 2016 Subaru BRZ with 48,000 miles demonstrated a repeatable gain of 7.5 whp and 5.4 lb-ft of torque. While modest, this is a significant improvement for a simple, reliable addition that also protects the engine from carbon buildup. For anyone with a direct-injected vehicle—especially the FA20 boxer—a catch can is a smart investment that pays dividends in performance, longevity, and driving satisfaction.

If you are considering a catch can for your own BRZ or other performance car, ensure you select a quality unit, install it correctly, and commit to regular draining. The gains are real, and your engine will thank you.