Track Day Breathers

Update by Steve Chryssos to the Chevrolet Camaro project car
Aug 8, 2012

Effective road race breathers are readily available. Any local welder can merge them with your engine.
Moroso's billet air/oil separator breathers aren't cheap, but the positive locking design appears to be leak proof.
Inside the air/oil separator breathers, you'll find foam elements and a perforated metal screen to trap moisture and vent fumes.
An O-ring seal and threaded lock nut secure the separator breather to your valve cover.
There's nothing like poking holes in perfectly good, high-dollar fabricated valve covers.
Weld-in aluminum breather tubes have internal baffles. That means we'd need some other way to add oil to the engine.
Steeda's all-aluminum oil fill cap kit features an O-ring to prevent leaks. Wear gloves when loosening the cap at operating temps. (Or dip your fingers in BBQ sauce.)
Moroso's universal air/oil separator tank is shown at left. The breather tank (at right) is likely unnecessary. It might help us avoid frequent draining. We'll know for sure after a couple of track days and street miles.
The finished valve covers look great. Scotchbrite pads are an easy way to create a consistent finish that's not blingy.
We'e ready to fire this engine and go for a test drive. We'll need to visit Marty's Mufflers. They'll merge our pre-existing exhaust system with our new Dynatech headers. After that, Holley's self-calibrating EFI can really do its thing.

It’s no fun getting black-flagged for a little oil smoke, simply because your breather system is not up to task.

It’s one of racing’s most annoying afterthoughts. You build a bad-ass machine with the best available parts. On track though, high rpm and high g-loads conspire to puke oil everywhere. Of course, concerned officials will call you in for that “little talk.” It’s no fun getting black-flagged for a little oil smoke simply because your breather system is not up to task. We’ve been there, and It seems a lot of track day enthusiasts have found themselves in the same situation. The good news is that track-worthy breather solutions are readily available. Follow along as we explore and apply various options to our small block Chevy.

Before we can examine breathers and separators, there are a couple of key engine subjects worth mentioning. A well-engineered oil pan will reduce the whipping and slinging effect of rotating parts (i.e., crank and connecting rods). Lateral and fore/aft g-loads are factored into pan design as well. Our Camaro has a “kick-out” style road race pan from Canton Racing that features swinging trap doors and a built-in windage screen. It’s sexy. Good oil pans actually reduce parasitic loss, while contributing to breather control. Ring seal is even more critical to oil containment. If your engine is experiencing blow-by, the breather system will likely be overcome. Cylinder pressure will push past the rings to the crankcase. Oil will be forced up and around. Blown gaskets and barfing breathers are usually the result. If your rings are shot, updating your breather system will not help.

With great ring seal and a well-engineered pan, we’re ready to tackle our Camaro’s breather system. Actually, we intend to over-engineer a breather system. We’ll apologize in advance for getting carried away with our design, but the goal here is 100% containment plus proper ventilation. On top of that, our Camaro is a street car, so we’re factoring in ease of maintenance as well. We have no desire to drain an oil tank every day. We worked with Moroso, as they have a dizzying array of breather system components. Hopefully, we can shed some light on each part’s use.

First, a shopping list. All part numbers are Moroso, unless stated otherwise.
-Fabricated Aluminum Valve Covers: PN 68335
-Weld-In Breather Tube Kit with Filtered Breathers: PN 68800
-Positive-Locking Oil Separator Breathers with O-Ring Seal: PN 68788
-Air Oil Separator Tank - Universal: PN 85474
-Breather Tank with 3/8” Ports: PN 85473
-Steeda Weld-In Oil Fill Cap Kit: PN 2075

The previous version of this engine sucked fumes into the base of the carburetor by way of a traditional PCV valve. Those fumes were then burned off during the combustion process. Upon teardown, we found that over a few years, a sooty residue had collected in much of the intake tract. Yuck! On some cars, PCV-based breather systems can even cause detonation at high rpm. Today’s alcohol-laced fuel attracts moisture, which can only make matters worse. PCV systems are fine for street cars. As rpm increase, they can become a detriment. With our new design, the PCV valve is deleted. Instead, air/oil separator breathers are mounted on each valve cover. They, in turn, lead to a remote mounted air/oil separator tank. That’s a lot of air/oil baffling! Time will tell if redundant separators end up trapping moisture at the valve covers. The alternative is frequent tank draining. We used Moroso’s universal air/oil separator tank part number, but bolt-on kits are available for late model cars, such as Subarus and Mustangs.

With fumes and moisture extracted, we also need to get fresh air into the system. It’s out with the bad and in with the good. For ventilation, we originally planned a breather tank located just beyond the air/oil separator tank. Smart people suggested that we instead need traditional breathers mounted at the valve covers. So we dove back into the Moroso catalog and found a weld-in breather tube kit. The tubes feature internal baffles to keep oil from dousing the filtered breathers. As for that extraneous breather tank, it will remain for now. Connected directly to the air oil separator tank, the breather tank can serve as vented overflow. We can always delete it from the system later. We’re hoping to drain this double-reservoir system as sparsely as possible. We might also eliminate one of the valve cover-mounted air/oil separator breathers. We fully intend to experiment with various combinations.

Baffle obsessed, we completely failed to factor an oil fill cap into the equation. We came up with a weld-in kit from Steeda that features a knurled aluminum cap and an O-ring seal to eliminate yet another potential leak point. The only downside to this all-metal design is that it gets quite hot to the touch at normal operating temps. Unless you’re a Polynesian tribal fire walker, wear gloves to break the hot cap loose.

A local welding fab shop added the breather tubes and oil fill cap to our Moroso fabricated aluminum valve covers. Total cost for welding was $25. After cleaning and brushing with Scotch-brite pads, our bespoke valve covers turned out to be the coolest, most purposeful looking parts on our engine. More importantly, we expect nothing less than 100% containment with full ventilation, as well as minimal maintenance on the street. We don’t recommend installing this many breather components to your track day toy, but we hope you get a better sense of what’s out there. Down the line, we’ll generate an update regarding which bits were deleted for this fresh engine. Your results may vary.

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