[GTS Dean]

CATWOOD sold me this Mishimoto air/oil separator a few years ago when he unloaded his Gen2 and went to Gen 4 & 5s. With my long motor saga, it took 3 years to finally get it installed.

I drilled out the rivet holding the OEM airbox's center screw anchor on the cross member and replaced it with a Riv-Nut. I moved the rubber tee in the valve cover breather collector inboard with a new plastic tube and went to one inlet. I installed a 5/8" vacuum cap for the airbox to plug the old valve cover breather port. The convoluted tube had taken quite a set over the years, so I slipped it over a wooden dowel and relaxed it with a heat gun.

The other inlet got a 45* nipple and an extended 1/2" hose to the block breather hose. The PCV valve is installed below a 90* from the suction outlet and a 3/8" hose runs to the tee feeding the back side of the throttle bodies. I did up a little bracket to hang the can from and it turned out very nicely.

 

[martyb]

Well done! This is the next project for me as well.

 

[GTS Dean]

I just got to thinking about the PCV valve. The poppet is held closed by gravity, so it needs to be installed relatively vertical. In this case, it's upside down and therefore open all the time. I may need to investigate the Orifice Control system in the '98+ cars. They used a metering orifice in there someplace.

 

[GTS Dean]

I checked out the Orifice PCV setup on the '98+ cars. The short hose from the block grommet comes up directly to a new tee that feeds a nipple behind each TB. Instead of the PCV valve, there is a 3mm +/- metal orifice in the entry side of the tee. After a good bit of reflection, I decided that most of my car's issues were likely from the valve cover breather nipples and the tee connection going to the passenger side of the air box.

I ended up reinstalling the PCV where it originally was and plugged one of the two catch can inlets. I bought a little more hose and a barbed brass 90* elbow from Amazon. I then came from the can outlet, over the upper radiator hose to the new elbow and back into the airbox nipple. I found my box with all the constant tension heater hose clamps that I took off years ago and they turned out to be the perfect size for the new routing. I'm pretty certain this will be the winning ticket for oil control at the track in the future.

The can only has a few drops of oil collected in it after 450 miles of street driving.

 

[Skidmark]

Could someone help me understand what each component of the CCV and Valve cover breathers is for? I was looking at the MotoIQ writeup and they use an oil separator in the PCV circuit, and a vented catch can for the valve cover breathers - is that a recommended setup?

 

[GTS Dean]

The Positive Crankcase Ventilation (PCV) valve is the first pollution control device required on US cars back in 1967. It is basically a gravity poppet valve that is pulled open during high engine vacuum and meters combustion blowby back into the intake manifold behind the throttle plates and into combustion chamber.

The Vipers have a block top vent under the manifold behind the t-stat. In 1998, they did away with the poppet and used a small orifice that is open all the time.

The Gen2 also collects valve cover blowby and oil from the nipples at the front of each. These are tee'd together and gasses are sucked into the airbox behind the filters, and back into the manifold. Venting to atmosphere doesn't dilute the incoming charge, but causes atmospheric emissions that are otherwise controlled.

 

[Skidmark]

The Positive Crankcase Ventilation (PCV) valve is the first pollution control device required on US cars back in 1967. It is basically a gravity poppet valve that is pulled open during high engine vacuum and meters combustion blowby back into the intake manifold behind the throttle plates and into combustion chamber.

The Vipers have a block top vent under the manifold behind the t-stat. In 1998, they did away with the poppet and used a small orifice that is open all the time.

The Gen2 also collects valve cover blowby and oil from the nipples at the front of each. These are tee'd together and gasses are sucked into the airbox behind the filters, and back into the manifold. Venting to atmosphere doesn't dilute the incoming charge, but causes atmospheric emissions that are otherwise controlled.

I think I understand - you rerouted the line from the valve cover vents into one of the oil separator ports and capped off where it normally connected into the airbox. Then you also ran the line coming out of the PCV valve into the same oil separator and the line from the 3rd oil separator port back into the intake manifold that the PCV used to connect to. Does that sound right? So you used a single separator instead of two separators as in the MotoIQ article right?

In this 3-port setup, is it ok for the air to flow from the CCV/PCV into the valve cover vents, or is a check valve needed so that air is only allowed to exit the valve cover vents?

 

[GTS Dean]

That's actually how I originally set it up. However, I changed it back to stock crank case PVC setup. I plugged one inlet port on the can and am now pulling a vacuum through the can to the valve covers via the airbox nipple.

It seems that other folks experience substantially more oil accumulation through the PCV circuit. However, my car always slobbered oil from the air box drains at the track. The only place that oil comes from is the valve cover nipples.

 

[Skidmark]

That's actually how I originally set it up. However, I changed it back to stock crank case PVC setup. I plugged one inlet port on the can and am now pulling a vacuum through the can to the valve covers via the airbox nipple.

It seems that other folks experience substantially more oil accumulation through the PCV circuit. However, my car always slobbered oil from the air box drains at the track. The only place that oil comes from is the valve cover nipples.

If you had the PCV and Valve covers leading to the same separator, then you can't really tell how much oil each circuit is responsible for right? I thought the main point of adding a separator to the PCV was because oil inside the intake charge could cause pre-ignition/detonation, so getting the oil out of the PCV circuit was a must.

I have a Paxton SC on my engine, so I believe that means my intake manifold would see positive pressure in some circumstances...in my case, do I need to route my separator output to the intake side before the compressor so that vacuum is always seen?

 

[GTS Dean]

in my case, do I need to route my separator output to the intake side before the compressor so that vacuum is always seen?

My feeling is Yes. The back of the throttle plates are pretty much always at a vacuum state.