Fresh air for pvc
Thread Starter
Racer
Joined: May 2012
Posts: 427
Likes: 10
From: Texas
Fresh air for pvc
I’m pulling fresh air and have read that it needs to come after the MAF sensor and before the throttle body. Can it come before the MAF sensor and if not why between the two?
Thx Rich
Thx Rich
No Hostility Be Happy
Joined: Aug 2018
Posts: 10,082
Likes: 7,398
From: South Hill Wa
2022 C5 of the Year Finalist - Modified
2021 C5 of the Year Finalist - Modified
Before the MAF would be pulling unmetered air. In between is metered and no vacuum.
What throttle body are you using that doesn't have a fresh air supply nipple already ported into it?
What throttle body are you using that doesn't have a fresh air supply nipple already ported into it?
Pro
Joined: May 2013
Posts: 740
Likes: 83
From: MN
The PCV valve is sucking air out of the crankcase into the intake manifold. The rule when running an engine with a MAF is that all air going into the intake manifold must be metered by the MAF in order for air/fuel calculations to be correct. (For anyone who wants to point it out, yes, I know blowby exists, no, I'm not factoring it in). So, the fresh air coming into the crankcase has to be metered, thus you have to pull it from after the MAF. Otherwise you will have a constant stream of unmetered air entering the intake through the PCV valve.
Thread Starter
Racer
Joined: May 2012
Posts: 427
Likes: 10
From: Texas
The PCV valve is sucking air out of the crankcase into the intake manifold. The rule when running an engine with a MAF is that all air going into the intake manifold must be metered by the MAF in order for air/fuel calculations to be correct. (For anyone who wants to point it out, yes, I know blowby exists, no, I'm not factoring it in). So, the fresh air coming into the crankcase has to be metered, thus you have to pull it from after the MAF. Otherwise you will have a constant stream of unmetered air entering the intake through the PCV valve.
Thanks TastyBacon!
So based on that I have a vented oil cap which would also be bring in unmetered air and should be removed? The only fresh air coming into my pvc system should be metered air being that I have a MAF sensor? I’m running a ls2 based 402 having 625 crank hp, is this sufficient to keep pressure down.
Really appreciate the time.
regards Rich
Thx
Last edited by Titan22; May 1, 2019 at 10:26 PM. Reason: Changing question for better responce
