An inevitable truth about the internal combustion engine is that each one produces some level of blow-by: the gaseous combination of oil vapor, unburned fuel and soot that makes it past piston rings during the combustion process. While OEMs offer closed crankcase ventilation (CCV) and/or positive crankcase ventilation (PCV) systems to keep oil and fuel from re-entering the intake tract, none are 100-percent effective at stopping it. For decades, enthusiasts and automotive-minded people everywhere have turned to the use of catch cans in order to keep oil from recirculating back into their engines. One company on the leading edge of catch can technology is Mishimoto of Wilmington, Delaware. Its latest product, a universal carbon fiber baffled oil catch can, offers highly efficient air-oil separation, easy serviceability and unmatched cosmetic appeal, all in a compact, lightweight package.
If you’re making considerably more horsepower than stock, chances are pretty good that your engine is creating more blow-by than stock. This is especially true in diesel applications, where forced induction and direct-injection contribute to a fairly extreme combustion process. In possession of one of Mishimoto’s carbon fiber catch cans, we decided to install it on an engine notorious for its blow-by issues: a 7.3L Power Stroke. Equipped with a CCV system from the factory, the integrated breather filter does a poor job of stopping oil from migrating back into the intake stream. This contributes to blown intercooler boots under high boost conditions and premature deterioration of the boots themselves. Thanks to a Cyclone baffle design being incorporated into Mishimoto’s carbon fiber catch can, all of that is a thing of the past for the 7.3L candidate we installed it on.
For a closer look at how Mishimoto’s new carbon fiber catch can works and just how easy it is to install, keep scrolling south.
First-Class Packaging
While we agree that Mishimoto has created one of the sleekest catch cans on the market, the top-shelf packaging makes for a great first impression. We typically don’t swoon over packaging—we’re more interested in the part inside the box—but the overall presentation is worth admiring before digging in. We’ll note that, as a universal product, no hoses are included.
More Charm
Once the box is removed from the clear plastic it ships in, the lid opens by pulling the nylon tab located on the side of the box. The lid is magnetic, so there is no tape, adhesive or staples to remove. Upon opening the folded lid, you’re met with a Quickstart Guide booklet for the catch can that doubles as a product brochure. You also get a Mishimoto sticker. Once again, we stopped and took note of the first-rate packaging. So far, things looked like a million bucks—and we hadn’t even pulled the catch can out of the box yet.
Improved Aesthetics
With the catch can freed from the snug-fit, plastic mold it ships in, we had the ultra lightweight, carbon fiber assembly in our hand. Not only does the 3K twill weave carbon fiber body reduce weight over competing products, but it looks absolutely killer. The base (up top) is made from 6061 aluminum.
What’s Inside
A quick, quarter-turn of the carbon fiber body separates it from the base, which makes oil level inspection an effortless process. The catch can body’s 7.4-ounce fluid capacity lengthens service intervals as well. Secured to the inside of the catch can base you’ll find a high-flow filter, which adds protection without affecting CCV pressure in high-boost applications.
Cyclone Baffle
Inside the body, a baffled (and indexed) insert is utilized. For optimized air-oil separation, Cyclone baffle technology is employed, with the baffle’s blades designed using computational fluid dynamics. This style baffle removes oil from the CCV system very efficiently, allowing only air to return to the engine.
Performing the Install
In order to access the factory CCV breather filter on our 7.3L Power Stroke test candidate, the cold air intake had to be removed. On all 7.3L engines, the breather filter (i.e. “doghouse”) was located at the driver side rear valve cover. Another upside to running the Mishimoto catch is that it’s possible to utilize an aftermarket cold air intake void of a provision to accommodate the factory 90-degree CCV elbow (such as the Irate Diesel system shown above).
Tapping Into a 7.3L's CCV System
The factory CCV filter breather box is sealed to the valve cover via O-rings on a 7.3L Power Stroke. Similar to many other systems, the 7.3L’s CCV system allows crankcase vapors to be drawn into the engine’s air intake circuit while the breather filter, in theory, keeps oil from migrating into the intake system. However, and as we mentioned in our introduction, the 7.3L is notorious for its blow-by issues, which was reason enough for the owner to route his CCV gases to atmosphere. The hose shown attached to the CCV filter breather box above will send blow-by to the Mishimoto catch can, where oil consumption for the high-mile Power Stroke can be better analyzed, before being vented to atmosphere.
O-Ring Sealed, Aluminum Fittings
With a spot picked out to mount the Mishimoto carbon fiber catch can, both ½-inch M16 x 1.5 aluminum fittings were installed. After their O-rings were hit with a coat of fresh engine oil, one was threaded into the inlet port, the other into the outlet port and each was tightened up using a 17mm socket and ½-inch ratchet. Mishimoto also offers an optional 90-degree swivel banjo fitting, as well as a catch can petcock drain kit for its carbon fiber catch can.
Multiple Mounting Options
To check the catch can’s fluid level during oil change intervals, the owner mounted the Mishimoto catch can along the driver side frame rail, not far from the oil filter’s location. Above, you can see the catch can being mocked up before any holes were drilled. Made from CNC-machined aluminum, the bracket can be mounted as shipped or rotated 180 degrees to suit different mounting preferences. The bracket makes use of 5mm hex head mounting screws.
Stringing Hose
Once the catch can bracket (and base) were mounted to the frame rail, we routed the hose we’d previously connected to the CCV breather filter to the ½-inch inlet fitting on the Mishimoto catch can. From there, the hose was cut to fit, pushed over the barb on the fitting and received added clamping insurance in the form of a hose clamp.
Aesthetically Pleasing, Fully-Functional
The last item of business entailed adding a short section of ½-inch hose to the outlet fitting on top of the catch can. Once the hose was forced onto the barbed outlet fitting, it too was graced with a hose clamp. Then the rest of the hose was routed along the frame rail and secured via zip ties, followed by the quarter-turn install of the carbon fiber catch can body and a test drive.