Check Valve why do we need them? - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

GenF-GTS · 02-01-2015, 08:44 AM

Firstly I have an elite catch can installed with the check valve but I am wanting to get a better understanding of why it actually needs the check valve.

From what I understand is the check valve is a 1 directional flow eg if flow reverts in the opposite direction the valve closes and doesn't allow it to pass the valve.

When our LSA engine is under boost pressure more crankcase pressure builds up and is released through the PCV system and through the catch can/check valve. During this boosted stage of the engine the valve is open as the direction of air flow is in the same direction as the valve in the open position.

When the engine is running at idle or even highway cruising 60-70mph the engine is under vacuum at this point air is being sucked from the snout into the catch can and the valve is still open.

So my question is at what point is the valve closed and why is it needed?

To me it appears that the valve will always be in the open position, it's either under boost/vacuum at the same time or it is under vacuum and the flow is in the right direction.

GenF-GTS · 02-02-2015, 02:15 AM

bump

vatechguy3 · 02-02-2015, 07:42 PM

I have the elite can too, but when i ordered it they told me i did not need a check valve.

Tony

Unreal · 02-02-2015, 08:21 PM

Don't need one unless the dirty side sees boost, and on a PD blower if you are before the rotors that won't happen.

BattleScarredSoldier · 02-07-2015, 01:53 AM

Great, was just wondering this myself. Good thread and info!

02-01-2015, 08:44 AM	#1
GenF-GTS Account Suspended Drives: none Join Date: Oct 2012 Location: Sydney Australia Posts: 571	Check Valve why do we need them? Firstly I have an elite catch can installed with the check valve but I am wanting to get a better understanding of why it actually needs the check valve. From what I understand is the check valve is a 1 directional flow eg if flow reverts in the opposite direction the valve closes and doesn't allow it to pass the valve. When our LSA engine is under boost pressure more crankcase pressure builds up and is released through the PCV system and through the catch can/check valve. During this boosted stage of the engine the valve is open as the direction of air flow is in the same direction as the valve in the open position. When the engine is running at idle or even highway cruising 60-70mph the engine is under vacuum at this point air is being sucked from the snout into the catch can and the valve is still open. So my question is at what point is the valve closed and why is it needed? To me it appears that the valve will always be in the open position, it's either under boost/vacuum at the same time or it is under vacuum and the flow is in the right direction.

02-02-2015, 07:42 PM	#3
vatechguy3 Drives: 2014 ZL1 M6 Join Date: Jul 2014 Location: Virginia Posts: 493	I have the elite can too, but when i ordered it they told me i did not need a check valve. Tony __________________ 2014 ZL1 M6 Bone stock, for now! 2001 Z28 M6 !cags, !air, FTP 85mm Lid, Z06 85mm MAF, P&P TB !4x4, Strano Springs, Strano Sways, Koni 4/4s, Watts Link ARH LTs, ARH catted Y, SLP catback with Dual/Dual Muffler, SLP CME and Valance OE Wheels Machined Face C5 DDs, 18x10.5s, with 295/35-18s on all 4 corners! 352rwhp and 366rwtq

02-02-2015, 08:21 PM	#4
Unreal Drives: 2006 Z06 Join Date: Oct 2010 Location: Gilbert, AZ Posts: 5,712	Don't need one unless the dirty side sees boost, and on a PD blower if you are before the rotors that won't happen. __________________ Nick Corvette Z06 -1200ish rwhp

02-07-2015, 01:53 AM	#5
BattleScarredSoldier Drives: 14 Camaro ZL1, 87 Grand National Join Date: Sep 2014 Location: Houston, TX Posts: 131	Great, was just wondering this myself. Good thread and info! __________________ Vengeance Racing + Cat and Muffler Delete > Viagra

02-02-2015, 02:15 AM	#2
GenF-GTS Account Suspended Drives: none Join Date: Oct 2012 Location: Sydney Australia Posts: 571	bump