Review: Peterson’s Externally Vented Air-Oil Separator

Most modern automotive engines utilize a Positive Crankcase Ventilation system that is designed to recirculate oily engine gases back into the engine from the crankcase through a variety of methods. For most engines, this is just fine, but if you have a performance engine, it may not be the best way to control crankcase pressures, especially if you’re running a turbo or supercharged engine.

In the case of our Project Wild E. Coyote, our turbocharged 2011 Mustang GT, we found that we were definitely in need of some way to better control the engine vapors. See, we’ve found that the Coyote engine doesn’t perform so well when it’s sucking up a bit of oil and depositing it back into the engine, and the realization of such sent us looking for a solution.

Left - Peterson Fluid Systems' and Fragola Performance Systems teamed up to provide us with a catch can solution to our oiling system issues. Right - The canister can be drained by opening up this -06 AN fitting on the underside.

Enter Peterson Fluid Systems, one of the aftermarket’s premier engine oiling experts. “Peterson’s catch can [PN 08-0400] is original equipment on the Cobra Jet, but that particular part number vents through the can to the atmosphere. I wanted to run one on our project car to use once we got the turbo system installed to prevent any issues. The placement of the catch can puts it right in the middle of where the air conditioning system’s intake is on a street car. From talking to a few people that had tried it, they were getting some oil smell into the car, ” explains Wild E Coyote’s handler, and Power Automedia Group Editor Mark Gearhart.

We re-used the factory PCV hose connections, but in order to get them to mesh cleanly with the Fragola Push Lite hose, we needed to grind off the barbs on the fittings before sliding the hose on. We also used shrink-hose to seal the connection up tight.

After a conversation with Peterson’s Mike Morten about the issue, Morten enlisted the help of Peterson’s engineers and pointed them toward the drawing board to see if they could solve the problem, and the result was a new part number; 08-0400-COYOTE.

“It functions just like any other catch can – you route the blowby that comes out of the valve covers and direct it into the can, where the airflow slows down through the baffle and the oil falls out of the airstream. The two -08 fittings are separated from the -12 outlet by a baffle – basically a can inside the can. The air can then be directed either back into the engine, or you can route the outlet hose away from the engine and down underneath the car, and this prevents the oil smell from entering the passenger compartment,” says Morten.

According to Morten, the modern PCV systems send the crankcase air back into the intake system to be re-burned, but that can lead to hot spots in the pistons and detonation, and taking oil out of the incoming airstream helps performance and consistency. 

“For a forced induction application, because of the way the incoming air from the catch can gets routed through the intake, the power adder can actually pressurize the can because the inlet is just behind the throttle body. When pressurizing the intake manifold, that air has to go somewhere so it will pressurize the catch can. So this is why we recommend running an open vent line routed out of the engine bay on a boosted vehicle,” says Morten.

Simply cut a little section of the factory firewall padding and run two self tapping screws into the firewall to secure the mounting bracket.

Left - We've found that immersing the Push Lite hose in hot water prior to installation on the Push Lite barb fittings helps to soften it up and allow it to slide over the barbs. Once the hose cools back down to temperature it provides a super-tight seal on the fitting. Middle - Our outlet was routed down into the transmission tunnel to keep the outgoing airstream away from the climate control system's intake. Right - If you have a naturally aspirated combination, the vent line is easily routed back to the passenger side factory PCV vacuum port on the intake manifold.

We subsequently received the very first one of these in existence and proceeded to have the Power Automedia shop team get it installed into Wild E. Coyote. Beautifully-finished black fittings were selected out of the Fragola Performance Systems catalog and consist of (1) -12 to -08 AN reducer [PN 491919], one 90-degree -08 AN Push Lite Hose End [PN 209088], and two straight -08 AN Push Lite Hose Ends [PN 200108] along with 10 feet of Fragola’s Push Lite Hose [PN 8000].

The finished product puts a bit of bling in our engine compartment, but more importantly, it keeps the oil out of our turbocharged mill.

The finished product puts a bit of bling in our engine compartment, but more importantly, it keeps the oil out of our turbocharged mill.

Installation was rather straightforward. Peterson provides the tank mount with the tank, but the PAM shop team, headed by Sean Goude needed to perform some surgery on the factory PCV hose ends to make everything mate up. A bit of grinding with a sanding disc and the issues was corrected.

“The capacity of the catch can is a quart, but you shouldn’t ever see more than a teaspoon or two of oil in the catch can over 3,000 miles. It’s not a ton of oil, but it’s certainly something that you don’t want in the combustion chamber,” says Morten.

Once that installation was complete, the hoses were routed, the can was tightened down for good, and our oiling issues were solved. While this may not make a difference in engine power for our car, it will help in the long-term with engine life and performance as the new setup ages. It also can prevent running issues, and even engine damage as a result of oil building up in the intake system.



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About the author

Jason Reiss

Jason draws on over 15 years of experience in the automotive publishing industry, and collaborates with many of the industry's movers and shakers to create compelling technical articles and high-quality race coverage.
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