Project Viper GTS - Part 9 - Bob's Air Oil Separator

Project VIPER GTS: Part 8 – Bob’s Air-Oil Separator

by Billy Johnson

All cars create blow-by and positive crank case pressure which forces oil and vapors into the engine’s intake to be burned off for reduced emissions.  This problem is worse on forced induction cars and performance cars driven at the track.  Not only does this oil gunk up the intake tract and valves, it reduces the octane of your fuel which robs power and causes detonation.  We installed a Bob’s Air-Oil Separator to the PCV valve and a catch can for the valve cover vent to see how much oil our Viper’s engine is pumping into the intake after some street and track use.

Bob’s Auto Sports has been around for many years catering to the Mustang and Corvette crowd with their Air-Oil Separator (AOS) kits that have been highly acclaimed for their effectiveness on the street and at the track. The AOS is an air-tight, sealed container that maintains the emissions-controlling effectiveness of the PCV system, while using baffles and steel filtering media to separate the oil from the crank case vapors so only clean air enters the engine.  The oil is collected in a reservoir to be drained at a later time.


Bob's Air Oil SeparatorMade in the USA and featuring a large chamber and superior filtering media, the Bob’s AOS is proven at the track in many racecars around the country.  We chose their Universal Oil Separator Kit with the standard bracket for our Viper.  We will go over all the parts needed at the end of the article.
Bob's Auto Sports Oil SeparatorsBob’s Air-Oil separators come in a variety of colors to match your engine bay.  We chose a discreet matte black to blend in and maintain an OEM look.
Bob's Auto Sports Oil Separator Ball ValveIt's important to regularly check and drain oil from the Air-Oil separator’s reservoir.  Bob’s AOS utilizes this high quality and smooth operating ball-valve which makes draining the oil very easy.  This is one of the nicest ball-valves I’ve worked with and it has a nice resistance to its actuation.  This is far better than the commonly used compressor drain valve. We decided to check the oil after 1,000 miles.
Bob's Oil Separator internalsAlmost the size of a can of soda, the Bob’s AOS is larger than it appears in images and it’s capable of holding a lot of oil.  Due to its solid construction, a strong mounting bracket is required to hold the AOS since it’s too heavy to be suspended from rubber hoses.  Bob’s model-specific kits (Mustangs, Corvettes, and Challengers) include all necessary brackets, hoses, barbed fittings, nuts and bolts to be installed with optional upgraded lines and hardware.
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Wednesday, September 21, 2016 4:02 PM
had one of these on my mustang... need to put it on my miata now
Wednesday, September 21, 2016 6:19 PM
BMW E46 owners are all to familiar with the CCV system. It's notoriously bad for failing and passing too much vapour or clogging with oily goo in the winter and failing spectacularly. It also results in excess carbon deposits in the intake and cylinder.

The advantage with a catch can is that you're not putting that gas/oil mix back in your oil pan, so your oil will last longer and protect better.
With this improved separator, you'll also reduce the amount of oil going to each cylinder, which should reduce carbon deposits (and improve performance).
However, we all know many modern cars, especially direct injected cars have excessive carbon deposit, likely due to inadequate CCV systems.
Other than venting to atmosphere and risking failed emissions inspection, seems like the only way to improve it is with a better CCV system.

Any idea how this AOS performs in the winter? It looks like new cars are going with CCV integrated into the engine block, to avoid the freezing issues.
Sunday, September 25, 2016 9:46 PM
How very underwhelming. Those parts look like they were designed by a high school metal shop student... who got a C in the class.
Sunday, September 25, 2016 9:58 PM
Thanks for the informative post @cartechs.

Please show us the beautiful solution you fabricated and some quantification of the better results you achieved or feel free to delete your post.
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