Selecting a PCV check valve

[donkeylips]

I'm looking for a good check valve to put inline with my PCV valve.
The specifications I'm interested in are:
1. Pressure rating
2. Vacuum Rating
3. Opening(cracking) pressure
4. Temperature range


Here are a few that I'm looking at:

US Plastic 3/8" Kynar - #64175
1. 1psi-150psi
2. 2inHg - 29inHg
3. .5psi
4. Not listed
Price: $1.28

RTM Racing Plastic Check Valve (8mm)
No technical specifications given. Appears to be the same as above.
Price: $3.03

McMaster-Carr #7775K53 Quick-Opening Brass Check Valve
McMaster-Carr #5670K83 Stainless Steel Adapter
1. 1,000psi max. @ 70 deg. F (275psi max. @ 72 deg. F Adapter
2. Not listed
3. .3psi
4. +10 to +400 deg. F (-20 to +750 deg. F Adapter)
Price: $22.33 + (2ea. Adapter @ $4.47) = $31.27


Does anybody have any long-term experience with these? The only reason I'm considering the brass McMaster valve is because it has the lowest opening pressure and is good at high temps. Although it does get below 10 deg. F here in Buffalo.

My main concern is the opening pressure. How much pressure is required for the stock PCV valve to open? Can one of these check valves impede flow?
Or am I worrying about nothing when all of the check valves seem to open at 1psi or less? What kind of pressure is normal in the crankcase?

 

[vr4play]

I am running the rtm racing one on my daily, my race car, and 2 of my buddies race cars and have had no issues what so ever. One of my buddies has a supercharged miata and he said he noticed the car running better after installing the check valve. I'm sure the stock miata pcv wasn't designed with boost in mind. My car see's 29psi and the valve seems to take it like a champ.

 

[turbofonz]

Me, and a few locals are all using the US Plastics one. It's what Calan (badass catchcan maker) recommends, so I went with it. No issues so far.

 

[transparentdsm]

i used to use the rtm one in my cars, now i just pull the check valve, drill it out(or remove the adapter on the intake, use that and put a bolt in the intake) and run it to a catch can, same as the other vent on the valve cover. if your not trying to do what i do then the rtm plastic on is the way to go. id still drill out the old check valve though.

 

[DynastyLCD]

you're doing it the hard way, Shane... /ubbthreads/images/graemlins/laugh.gif

if you have a spare stock intake manifold, the threaded port for the brake booster will also thread into the valve cover. there's your straight piece!

 

[G]

What about clogging with oil? Don't these things clog up?

 

[blacksheep]

so, trying to learn here...

You install these valves in line with the PCV valve? I thought buschur/RRE etc all said to remove PCV and just install a straight fitting and eliminate the PCV altogether. Whats the advantage doing it this way with the PCV in place?

S2000 guys all swear by krankvents...

click

 

[transparentdsm]

the pvc prevents boost pressure from going back into the crank case to prevent excessive pressure in the motor.

blaksheep: for 110 bucks its not worth it in any way what so ever. the plastic ones are good and cost effective.

G: yes the ones from the factory do clog up that is why its recommended to use the plastic one or run your valve cover breathers to a oil catch can.

Phil : i was trying to give him ways to do it with what he has right there. i have those fittings all over the place and a few intake manifold as well... freaking parts hoarding.

 

[matt92vr4]

I've always used Krankvents. They work great but are very expensive. I'm glad to see there is a cheaper alternative.

 

[alansupra94]

This might sound stupid, but could you guys post up diagrams of how you have your catch can/PVC system setup?

Always like to see what works for you guys.