Thread: Finding a way to Reduce Oily Blow By Gases

^^

I thought that the ECU has been designed to take into consideration the PCV blow by gases into their A/F ratios.

I'm going to fuel up tomorrow and will see if having a block off helps the MPG's or not hehe.

I did notice a little rougher idle with the PCV block off, one time it kinda felt rough while standing on a stop light.



Wait is does that mean having the PCV ventilated will increase the blowby or decrease it?

1. the blow by gasses are gasses that are pushed past the rings on the compression stroke, so yes, they are metered before they even get into the combustion chamber. Now you will notice the hose that goes back to the intake is plumbed AFTER the maf; it would be pointless to have it plumbed before the maf because that would cause a lean running condition. The ecu only makes compensation for metered air, nothing else. Metering air twice will cause a lean condition.

2. Having the pcv system ventilated to atmosphere will not change blowby at all, blowby is constant and the amount of blowby depends on how much compression is lost through the rings. Now, the pressure in the crankcase and valvecover will depend on how well the pcv system is set up. Most likely if you vent everything to atmosphere you will lose power by increasing the pressure. You want the crankcase to be under vacuum or zero pressure if you can help it. the pcv valve helps this, among other things. It is a lot harder to descibe by typing, but hopefully you are grasping what I am saying.

A gt42r turbo on a civic (with 2 -10an fittings with catch cans, in other words BIG) still has around 10psi of crankcase pressure when the turbo forces 40psi! Now that is some serious pressure. On a typical engine NA you won't see enough blowby to affect the power output that much, but on a turbo engine 10psi of pressure will increase the windage loss and reduce power.

Interesting Info



So the blow by gases are not necessarily post burned exhaust gases right?

Makes sense to why the breather is after the MAF.



Now I fueled up today and got 23 MPG, this is with the PCV disconnected. So it's a little bit of an improvement. But I did recently redo the valve cover gasket and resealed it. So maybe that is what helped instead of the PCV block off.

All I know is, the car has been running more like crap with PCV blocked off. Now since I found the bad Vacuum Cut valve, and replaced it I can see if that is what is really eating up my MPG's hehe.



Woa 10 PSI? Man thats a lot

What do you guys think about something like this:



This would reroute the oil that goes through the PCV valve back to the crankcase, while feeding the intake manifold with the not so oily blow by gases.

Huh? how are you planning to ensure that the oil is going back?

Also, this is bad because you now have a nearly direct line from the intake to intake manifold (going to confuse your ECU because the amount of air coming in isn't going to agree with the TPS reading).

Gravity haha. Maybe some kind of a filtration method. The current filtration method that I have works actually quite well.

As for the extra air, one way valves. So basically bunch of PCV valves

Just a speculation:

Now it seems like the one main reason blow-by will happen is because of worn piston rings. My new engine doesn't nearly has as much blowby

i just read this whole thread and im trying to get the point on why you guys are doing this... is this another save .0000001 mpg by changing something thread

Lol Jen Jen... With high blow by engines, like my old one was, that blow by would have oil that would go into my intake.

This quote is the best reason:

so what setup is the best?