The talk on "check valves"

[Chief]

I quote from agp...

".....You should only be running a properly sized check valve (like the one above) if and only if you're removed the factory PCV. You should never, ever never, never, ever run a check valve in conjunction with the factory PCV. You've now added an additional airflow restriction on probably the most important system of your engine...."

I NEVER really saw the point of the "check valve band wagon" If you pvc is working correctly, and your running a SEALED catch can, OR no catch can at all and strait to the TB, whats the problem??? Ive ran with and with out catch can to tb, and never had a issue?

So whats with this "check valve" talk?

Maybe jon can explain why so many are turning to buy these check valves. NOT TO MENTION many of the peps using check valves Also do NOT get rid of there pvc's?

[[H]ardMacK]

Check valves are silly when your car is properly setup... And as many people that have PCV and Crankcase pressure isssues on this board might give you a clue.

[04blusrt_4]

Pretty simple, factory pcv valve when its BRAND NEW allows reverse flow into the crankcase when under boost. The escape point of this crankcase pressure is on the other side of the valve cover into the intake track.

Sooo....a checkvalve stops this entire problem. Most people are shooting for ZERO crankcase pressure, not vacuum in the crank case. No matter how many check valves are in place between the throttle body and the stock pcv location, there's no "flow restriction" unless you have something blocking the connection on the driver side of the valve cover.

So here are the choices...

(1) leave it completely factory like setup (no check valve, only pcv, valve cover to intake or air hooked up) which means you will bleed boost into the crankcase via the stock pcv and then let it evacuate out the breather on the other side of the valve cover . In my opinion this is a shit setup and leaves at least slightly higher than atmospheric pressure in the crankcase, also means youre sucking in oil vapors via the throttle body connection which lowers octane and caused knock and smoke.

(2) have it like factory but install a check valve and catch can to the factory pcv line, keep connection to intake or to air on the driver side of valve cover. This eliminates any boost bleeding into the crankcase and any oil vapors from entering the throttle body. The cracking pressure of the check valve will slightly decrease overall vacuum at the crankcase during normal driving and idling, but has no effect to crankcase overall pressure during WOT. In fact, crank case pressure will be less as described earlier due to eliminating the factory pcv leaking.

(3) Same as number 2 except you add a catch can to the drivers side of valve cover, and then connect to the intake. This eliminates any oil vapors from entering the turbo compressor and intake track, which again can lead to decreased octane and poor performance.

There is no "proper" setup that justifies not have a better pcv or check valve in place than the factory one, its a factory defect. I have held a brand new one and been able to blow through it, its just not up to par.

[Silver_Surfer]

This is another, which oil is best, kinda thread. I have read the three sides about check valves:
1. not using one
2. using a 1/4" check valve
3. using a 3/8" check valve

Smoking Turbos - EXPLAINED Check Valves

It all depends on what works for you. I have light mod's and the 1/4" check valve I bought from PTP a few years back made an immediate improvement in boost levels. No more boost flux. It has been on my car with the stock PVC valve and aftermarket catch can for more than 30k miles without issue. At 102k my car is running great.

So, if you don't have boost flux issues and are happy with your car, great, don't add one.