Mishimoto 2013+ Subaru BRZ / Scion FR-S Direct-Fit Baffled Oil Catch Can System, Part 1: Product Introduction

Interested in picking up this awesome catch can system? Check out more details on our product page!

Mishimoto Subaru BRZ / Scion FR-S Baffled Oil Catch Can

Why a Catch Can?

Catch cans are used only for turbocharged vehicles, right? This is a question we hear all the time. Yes, a turbocharged vehicle is more likely to produce greater blow-by, resulting in a more prominent collection of debris in the intake manifold and tract. That being said, any engine is certainly susceptible to oil and fuel collection due to the use of PCV and CCV systems, which improve engine efficiency and provide cleaner emissions. Mishimoto has been working on developing several direct-fit oil catch-can systems for a variety of vehicles. So far we have completed kits for the Subaru WRX/STI for 2008–2015. We have also experimented with a kit for the BMW E90, a vehicle that suffers from intake valve buildups that require frequent servicing. With the arrival of our 2015 Ford Mustang EcoBoost test vehicle, we also began tackling a kit for that particular model. Our most recent project involves two of our favorite vehicles, the Subaru BRZ and Scion FR-S.

We already carry a ton of products specifically for this chassis, including an aluminum radiator, cold-air intake system, silicone coolant hose kit, and a direct-fit oil cooler kit. To round out the GT86, we decided to create an easy-to-install catch-can solution that would help vehicle owners keep their engines clean. The best time to install a catch can is before the serious buildup begins, so we are hoping to catch these engines before they have serious mileage on the odometer.

FR-S on Mishimoto dyno
FR-S on Mishimoto dyno

One interesting factor that affects valve buildup is the use of direct injection systems on modern engines, including your FA20. You will find that several of the more recently released direct injection engines have valve deposit issues, and this is no coincidence. To understand why this occurs, you must first take a look at how these different injection systems function.

First, we have traditional port injection. In an engine with this system, the injectors are placed inside the intake manifold, and they produce a stream of fuel to atomize and mix with air. This mixture then enters the combustion chamber through a valve.

Port injection cutaway example
Port injection cutaway example

So, why is the port injection system less susceptible to valve deposit buildup? Well, as you may know, gasoline has very strong solvent properties, meaning it is fantastic for removing grease, tar, and waxes. (Some guys you find in the garage will even clean their greasy hands with a splash of gasoline!) The fuel mixes in the manifold and then passes through the valve to clean much of the debris and buildup. However, any point before the injection site is still susceptible to sludge buildup. This includes the throttle body and intake piping/tract.

Now to compare, let’s take a look at direct injection.

Direct injection example
Direct injection example

The fuel injector is located right in the combustion chamber, unlike the intake manifold location for port injection. This means the valve will not be affected by fuel, so its cleaning properties are not utilized. This setup is one of the primary reasons for direct injection valve deposit problems.

Numerous large vehicle manufacturers use this technology, so it must have some benefit. Direct injection of gasoline directly into the cylinder, results in smaller, more controlled explosions. This allows automakers to squeeze out greater fuel efficiency, resulting in more miles per gallon for your commute! It seems as if a majority of the recent adopters are having reasonable success with these systems, with only some minor bugs to iron out.

Obviously buildup of deposits on the valves is not a good thing, but you probably want to know: What does it mean for me? Will I ever notice a difference or see any negative impacts on drive-ability or reliability? More great questions! Internal combustion engines are not the cleanest machines on earth. They contain numerous fluids, put out a ton of byproduct, and commonly build up dirt and grime. Valve buildup is a small problem that can quickly escalate to a more serious issue. Deposit buildup can cause turbulence around the valve opening and even restrict airflow if the buildup becomes more prominent. The result is decreased performance and even engine misfires, not something you want. Check out below a shot of a dirty BMW E90 valve.

Deposit buildup in intake valve
Deposit buildup in intake valve

And take a look at what these are supposed to look like!

Clean intake valves
Clean intake valves

We want to keep these valves as clean as we can, to retain power output and keep the engine running optimally. So what should you do if you have an engine equipped with direct injection? Swap a port injection system? No, that would be quite expensive, decrease your fuel mileage, and be a complete nightmare. An easier way to reduce buildup is to install an efficient catch can setup. A catch can will remove contaminants (oil, fuel, etc.) from the engine before it enters the intake tract.

So why do these contaminants exist? Without going into too much detail, your engine features a CCV (crankcase ventilation) system that works to improve engine efficiency and emissions. During engine operation the crankcase generates pressure due to combustion gases passing the piston rings. This pressure is evacuated from the crankcase and is routed into the intake system to be burned in the combustion process. When the oil enters the intake, it coats the tract, throttle body, and valves. It is then burned in the combustion chamber, lowering the octane of the mixture. Although not optimal for performance, this creates a clean engine that requires no emptying of byproducts and contaminants (a common practice for most manufacturers.) Ideally, these contaminants should be separated, collected, and disposed of. This brings us to the function of our catch can!

CCV Systems Explained

For those who wish to learn more about CCV systems, read on! Otherwise, scroll down a bit for more information about this project.

Every engine is susceptible to blow-by from the piston rings, it is impossible to have a completely leak-free seal between the rings and cylinder wall. If pressure builds up in the crankcase, it will eventually find a weak point, normally a gasket or seal, and will result in fluid leaks. Two primary lines make up the CCV system equipped on the FA20 engine. The first, the makeup air line, routes from the valve cover to the intake piping. This line provides a light vacuum on the crankcase and is most used during wide-open throttle situations. The second, the ventilation line, routes from the back of the engine block to the intake manifold. This line utilizes the PCV valve and features a higher vacuum source than the makeup air line. The ventilation line is used during idle and part-throttle driving situations. The valve works to eliminate the pressure from the intake manifold so it cannot enter the crankcase. These two hoses/lines will function together to provide optimal crankcase pressures for efficient operation. Engines typically function better with a slight pull on the crankcase.

Mishimoto’s Plans

Now that we’ve discussed the need for a catch-can setup for the BRZ/FR-S, it is time to provide some detail for the kit we intend to put together. All our kits are direct-fit, but drivers could just purchase our universal catch cans and make them function with their vehicles. But, we want to take the guess work out of installing a can setup. We will include direct-fit brackets and lines and also provide detailed installation instructions so the process is simple and hassle free. Our goal is to make this kit appear as though it were factory-installed, and in reality it should be!

Before setting our engineers loose on this project, we decided to set a few guidelines for what our customers wanted out of this kit. We performed a reasonable amount of research through forums, our customers, and our vendors to help determine what product would best serve the BRZ/FR-S community. Check out our goal list below!

Project Goals

  1. Kit must be 100% direct-fit and include all necessary components for installation.
  2. Develop a PCV and a CCV catch can, and determine if both are necessary for the FA20.
  3. Catch cans must be easy to service, and fluid removal should be an easy process.
  4. Fully test the product to ensure safe and effective operation.

Now, as with other projects, we like to break these goals down and go into further detail about how/why we want to achieve each.


One of our primary goals for essentially all projects coming out of our shop is direct fitment. Our catch-can kits should fit perfectly and bolt into position using common hand tools. Fabricating brackets, finding lines, etc., can be a challenging/lengthy process for DIYers. For most, a kit designed for specific vehicles is the way to go (especially if it’s a great value for your dollar!). This kit will include direct-fit catch-can brackets that will mount within the engine bay. We are hoping to keep the lines as short as possible to avoid clutter, so strategic placement of the cans is vital. Our lines included in this kit will be pre-formed silicone; we are not throwing a roll of rubber hose in a box and calling this a direct-fit unit! Lastly, we will be using our baffled catch can, an extremely efficient catch can that uses a 40 micron bronze filter and internal baffling to promote increased separation of oil from air. We have had a ton of success with this can and hope to make it function with our latest kit!

Take a look at our catch-can!

Mishimoto Baffled Oil Catch Can
Mishimoto Baffled Oil Catch Can

This is a highly engineered product that really displays the talents of our engineering group! More on selection of catch cans in Part 2 of this build!

One Car, Two Cans

We will be designing a kit with two cans, one for each of the systems. Unfortunately, these lines cannot be combined into a single catch can due to pressure differences. We will be selecting optimal engine bay locations to ensure that the cans are not impeding space for other components. Also, for our RHD (right-hand-drive) owners, the firewall differences between the two cans will be important. To ensure we will need two catch cans, we will be testing both systems to see which produces a greater amount of byproduct. More on that below!


The baffled unit is completely serviceable and the filter is washable, providing a lifetime of use. We expect that most people purchasing this kit will appreciate a can that is easy to empty and does not require complete removal of the setup. Our plan is to have just the removable base come off, be emptied, and then reinstalled in a quick fashion. Once again, careful attention to can placement will be necessary.


Product testing is a huge deal within our engineering group. If it doesn’t pass our tests, it does not leave our garage. We do not produce products that are less than 100% functional, and we do our best to design the most effective solutions possible. For this particular project, we are planning to conduct real-world testing on an FR-S belonging to one of our accountants, and also a BRZ belonging to a member of our sales team. We should have no problem dropping by their desks to steal the keys for test fittings! We are also planning to install this kit on one of their vehicles for a long period of road use to determine the effectiveness of our system. Stay tuned for more on this later!


That rounds out our plans and goals for this project. If our R&D processes are effective, we should easily produce a kit that meets the needs of the enthusiast world.

Check back next time for a look at the mockup of our first prototype unit!

Thanks for reading, and feel free to follow up with any questions or comments!

Interested in picking up this awesome catch can system? Check out more details on our product page!

Mishimoto Subaru BRZ / Scion FR-S Baffled Oil Catch Can