PCV vs EVAC

[SpeierRacingHeads]

You have an engine that you can not run a vacuum pump.

Which system is better? If PCV, what is proper set up.

Engine in question is a drag race engine.

Not sure what they have going on here?

[rfoll]

If the engine is sealed and has no atmospheric breather, the system pictured will only function under crankcase pressure. I never liked the idea of oil saturated fumes going into the intake system and displacing a proper mixture. When I got rid of my pcv and started using regular breathers, I had oil all over the valve covers. The filter element over time becomes saturated with oil and eventually is pushed out by crankcase pressure. I started using the breathers with the tubes on them, such as would be used to plumb to an enclosed air filter case, and removed the foam sponge. The tube is plumbed to the back of the engine like the old road draft tube. I almost never find any oil at the outlet of the tube, no pools on the floor where I park the car or anything like that. It's amazing the contraptions I see at the track where people are fighting the problem.

DSCN1523.JPG

[ClassAct]

You can use both Chad. Even if it’s a drag car. The PCV does the bulk of the work when you are at idle and cruise back up the return road and in the pits. At WOT the Evac’s do the work. Even at cruise (any high manifold vacuum situation) both the PCV and the Evac’s pull crankcase depression. I suggest using a separator for the PCV. I always use both when I can.

[BillK]

When I was racing back in the late 70's and 80's the Moroso Pan Evac system was very popular. I ran it on the small block in my Camaro for years. Only problem with it is you cannot run it with any type of muffler because any back pressure will pretty much stop it from working.

https://www.moroso.com/crankcase-evacua ... stem25900/

[F-BIRD'88]

Think about where that oil is going.

On the race track surface.. Great for traction especially racing at night.. Ever seen a drag car suddenky go sideways about ½ to ⅔ down track at dusk?
Oil on the track.

[F-BIRD'88]

If you are blowing oil out the valve cover breathers your valve cover baffles are not working. Or your rings are not sealing. Most all aftermarket valve covers are made just to look pretty. Many have no functional oil baffleing for the breathers. You can fix that.

[SpeierRacingHeads]

Thanks Guys!

I asked because I'm doing this. I bought a 2002 Cavalier and going to run Super Stock. Looking at GT/FA with a 350/360hp with a NHRA factor of 330. I have some work to do on the car to run GT, but I'm up for the challenge!

[ChopperScott]

If it’s drag only, with no mufflers, I’d go with exhaust evacuation…

4E28BEC4-D43F-4785-88B7-F86955E1F79C.jpeg

[HQM383]

If it’s drag only, with no mufflers, I’d go with exhaust evacuation…

4E28BEC4-D43F-4785-88B7-F86955E1F79C.jpeg

Exactly. Pcv is useless on a drag car as it is closed at WOT.

[SpeierRacingHeads]

If it's useless, why does all the $45,000 Patterson Super Stock engines run dual PCV?

[fordified]

Chad,

Moroso sells a nice PCV oil/air separator. Everyone I know in SS or GT runs the crankcase evac to the headers but they don't really pull that much vacuum so YMMV on the dyno with thin rings.

Nice ride. Looks like a modified or comp car. Best of luck.

[ChopperScott]

If it's useless, why does all the $45,000 Patterson Super Stock engines run dual PCV?

Class rules?

[skinny z]

Swinehart_2_Web__91240.1564592189.png

I see what I believe to be an oil cap but no breather.
What let's the air in when the PCV is active?

Further to that, do you know what they are using for a valve? Adjustable perhaps?

[F-BIRD'88]

If it’s drag only, with no mufflers, I’d go with exhaust evacuation…

4E28BEC4-D43F-4785-88B7-F86955E1F79C.jpeg

Exactly. Pcv is useless on a drag car as it is closed at WOT.

The PCV valve does not Close @WOT. But there is a anti back fire safety valve function to stop a blow back crankcase fire. The flow pindle does move to the low vaccuum position against the pindle valve spring inside.
The low vaccum position creates more flow thru when manifold vaccuum is low (wot)

[skinny z]

pcv_9538c6f6c4d39b23b670c0beb763e658390c9536_4eff324de99501c6d64a2a837e4945ee1b850434.gif

Sort of like this.
Although it shows the valve is fully open at WOT.

And I'd still like to know where or if there's a breather.