PCV vs EVAC

General engine tech -- Drag Racing to Circle Track

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F-BIRD'88
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Re: PCV vs EVAC

Post by F-BIRD'88 »

That motor would likely be pulling quite a bit of manifold vaccuum at high rpm IMHO. But it looks like a hybrid PCV and Pan E-Vac system to me. I I every run into him at the track here, maybe I'll ask him.
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Re: PCV vs EVAC

Post by stealth »

That's the Nitrous line hidden in plain sight... :D
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Re: PCV vs EVAC

Post by skinny z »

I'm not seeing any outlet for a pan E-vac.
Typically fitted to the valve covers aren't they? Then on the header collectors.
But as Grumpy did back in the day, maybe a combination of both.
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Re: PCV vs EVAC

Post by F-BIRD'88 »

skinny z wrote: Wed Jan 12, 2022 9:48 am I'm not seeing any outlet for a pan E-vac.
Typically fitted to the valve covers aren't they? Then on the header collectors.
But as Grumpy did back in the day, maybe a combination of both.
You're not seeing the pan E-vac hoses coming off the side of each breather? ??

Yes I remember Grumpy's 331 sbc tunnel Ram Vega had a simular PCV like setup on the valve cover breather/oil separators 1970's era.
Last edited by F-BIRD'88 on Wed Jan 12, 2022 9:57 am, edited 1 time in total.
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Re: PCV vs EVAC

Post by skinny z »

F-BIRD'88 wrote: Wed Jan 12, 2022 9:55 am
skinny z wrote: Wed Jan 12, 2022 9:48 am I'm not seeing any outlet for a pan E-vac.
Typically fitted to the valve covers aren't they? Then on the header collectors.
But as Grumpy did back in the day, maybe a combination of both.
You're not seeing the pan E-vac hoses coming off the side of each breather? ??
Which picture are we looking at?
I was referencing Chad's first post.
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Re: PCV vs EVAC

Post by F-BIRD'88 »

The pic of underhood of a FJ Smith S/S car.
His front wheel drive conversion GM SuperStock cars are legendary. Smith Performance Specialities.
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Re: PCV vs EVAC

Post by skinny z »

Missed that picture before.
Yeah. I see the hoses through the fenders.
Interesting setup.
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Re: PCV vs EVAC

Post by SpeierRacingHeads »

steve cowan wrote: Wed Jan 12, 2022 4:50 am Unless you own or build these style of engines I doubt we will see inside of anything :D
My opinion is we should be thinking of what they are trying to achieve having to use that type of crankcase ventilation.
Those short blocks are more than likely turned over with a inch/LB torque wrench.
Blowby would be very low,maybe the low manifold vacuum at high rpm with that setup is worth a couple of hp and hundredths at the track.
I am sure Vortecpro put a video up a few years ago where he is spinning a short block over one handed,he must be very strong :lol:
https://www.youtube.com/watch?v=2aYJxjp0src
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Re: PCV vs EVAC

Post by Malvn »

Take a look at the way Bill Jones did the EVAC for the pinto ! :) I thought it was a Awesome idea Bill Jones came up with. :)

viewtopic.php?t=16468&start=30#p237013
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Re: PCV vs EVAC

Post by Joe Kraemer »

Malvn wrote: Wed Jan 12, 2022 12:37 pm Take a look at the way Bill Jones did the EVAC for the pinto ! :) I thought it was a Awesome idea Bill Jones came up with. :)

viewtopic.php?t=16468&start=30#p237013

That is what we modeled our headed EVAC system off of and pulled 7-8". On the dyno you could watch the vacuum gauge at idle and it would slowly rise to about 6 then as you went through the pull it would gain 1-2'" more.
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Re: PCV vs EVAC

Post by v6racer »

I'm just guessing, but is this possibly a carburetor limited class engine which might pull a significant vacuum down track?
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Re: PCV vs EVAC

Post by BradH »

I dug up the following after reading this thread. I don't recall where I came across it, and must not have been interested in whatever "Stage 1" and "Stage 2" were cuz I didn't bother taking screen-shots of them for reference at the time. Similar concept, except the PCV valves are eliminated and air/oil separators are used on each hose to the intake.
Screen Shot 2021-01-13 at 4.20.07 PM.png
Screen Shot 2021-01-13 at 4.21.11 PM.png
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Re: PCV vs EVAC

Post by SpeierRacingHeads »

Two of these type smaller separator tanks would be LW and compact!

Image
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Re: PCV vs EVAC

Post by Jeff Lee »

I was just researching Pan-e-vac system by Moroso which is the standard of Super Stock racing. I’m soon to have my SS/G AMX to the track.
I came across this:

https://www.c-f-m.com/performanceparts/ ... s-c744.htm

Which is a valve cover breather with a one-way check valve in it which allows crank-case pressures an outlet without pulling air back in.
I have used two-stage PCV’s in the past; Stage one would be a traditional PCV however we found on the dyno not all PCV’s are created equal and about the only way to get it right is to dyno a handful of various size (different applications) and see what works. Stage two is using a vacuum brake booster check valve mounted at the base of an air filter (must use filter and lid) with a hose attachment that ends up drawing crank-case pressure.
On pre-stage you have to hold around 5000 RPM for stage one PCV to do it’s thing.
Concept was good on the dyno, saw upwards of 12 HP. On the track? I dunno if I ever saw anything. I tried it active and de-activated. No difference.

I bought one of those CFM filters with a weld on bung. I also have a pan-e-vac. I believe I will install the oil fill tube on my intake manifold with a cap welded on top and the bung attached. What I don’t know is if I would run the CFM filter with or without the pan-e-vac. And maybe a PCV also??? I have one of those adjustable flow PCV valves:
http://mewagner.com/?p=444
Which may prove better than my previous attempts trying to find the perfect PCV.

Interested in hearing some responses as to what parts I should look into. Or all of the above? What do you think Carl?
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Re: PCV vs EVAC

Post by Jeff Lee »

PRH wrote: Tue Jan 11, 2022 5:31 pm The pan evac isn’t legal in Stock.
Not sure about SS.
Has always been legal in Super Stock. Or at least since the ’70’s
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