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Discussion Starter #1
I have a 93 coupe I am about to install a v3 si kit on it. ENGINE is stock short block f303 cam sve 170cc heads, cobra intake lower ported by tmoss, and long tube headers. I have sve aluminum valve covers with no baffle. I currently use a stock oil filler cap and stock pcv valve system. Should I run an open breather on the oil filler? When I tried that before it was like installing an air leak and the car didn't really like that (was told because the maf wasn't sampling the extra air coming in through the open breather).
The vortech kit INCLUDES a can of some sort that is supposed to address blow by. Do I use this and keep the sealed oil filler cap on? Dobi use the vortech supplied can device but put an open breather on instead if oil cap? What about the small tube from the oil filler stack to the throttle body? Does that stay? Do I just get a catch can setup like lmr sells? If so do I keep the small tube to the throttle body from the oil filler? Do I use an open breather with a catch can? Sorry so many questions but I want to set it up right the first time. Thanks
 

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I’m new to all of this and I have a similar set up as you
(Although not running yet)
It’s my understanding that if you keep pcv system then you need to put a check valve in hose between throttle body and pcv valve to help keep boost pressure from entering crankcase
You can’t have any breather caps with pcv or it creates a vacuum leak.

Or
You delete all pcv system and vent crank case to atmosphere using vented catch cans
And if you go this route large #10 or #12 hoses are preferred to each valve cover because you don’t want any restrictions of case pressure including blow by to push out seals.
I think on a street car a pcv system is nice to have because of less odors and Maintence but pcv system does have drawbacks which could be blow by oil reinterring engine unless you use a sealed catchcan to separate oil on its way back.
Just my understanding of all this stuff and it’s a bit daunting for me deciding which way to go.
But for me, on my street/strip 65 mustang with similar mods as you I went with catchcan set up. Mostly because it’s not a daily driver and the catchcan set up is simple to understand for my simple brain. 🤓
 

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you will need expensive evac system, or live with a never ending oily mess in the engine bay

I've seen dyno pull videos with people rags ziptied to some breather on new mustangs.......ghhhettto!
 

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To the original poster, don’t overthink it. Block off the PCV, remove the tube between oil fill and TB and cap them off, 12an fittings on each valve cover running to a catch can. Been done 1000’s of times by people that actually work on their car, and works great!!
 

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the principle remains the same

this is especially needed for a system that boosts the intake tract, ie hairdryers belt or exhaust driven

the intake valve contamination may not be to the same extent, but all the blowby products will still be in the intake, or drooling over the engine
 

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Discussion Starter #9
What about a catch can with one side going to pcv valve, other side going to oil filler pipe fitting where the small hose that would go to throttle body area would go and use stock non vented oil filler cap?or should that other line just go to the original FITTING on the upper intake?
 

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What Fireman said is really your cheapest option.

Also:
You can block off the line coming off the throttle body, that line actually supplies the fresh air that the PCV valve pulls through the crankcase, it does not suck vacuum because the opening is in front of the throttle blade in the throttle body. That is a high pressure area. Of course it will get boosted air too once you have the blower on so block it off.

If you put vent lines on the valve covers do two things, put the vents at the front and make sure there are baffles under the vents lines. If you do that you will keep a lot of the oil out of the lines and the catch can.
 

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What about a catch can with one side going to pcv valve, other side going to oil filler pipe fitting where the small hose that would go to throttle body area would go and use stock non vented oil filler cap?or should that other line just go to the original FITTING on the upper intake?

what about, doing right?

right is not cheap, cheap is not good.
 

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When given the option on a street car, I believe it's better to run a PCV system. If you are using a draw-through MAF, then it's not that hard. Two cans with single ins and outs will work fine. The PCV valve at back of intake goes into a can, and the other end goes to manifold vac source. This allows for the blowby fumes to be "filtered" by the can before being drawn into the intake manifold while operating in vacuum.

The fresh air side can go as follows. Run hose from filler neck nipple to another can and have the other side go to the supercharger inlet AFTER the MAF. Has to be post MAF so that the air being drawn into the crankcase and then ultimately through the PCV valve and into the intake manifold is metered. While in boost, the flow will reverse in this side and blowby will come out the filler neck hose, get filtered in the second can, and go into the blower inlet. If you make a lot of boost, you may need to use a hose of substantial size on this side to ensure enough crankcase venting under boost.

If you use a blow-through MAF, there isn't a great PCV solution. You can fabricate fancy systems that incorporate lots of one way vac and boost operated valves, but I don't recommend it. If a valve fails, you can pressurize the crankcase. There are other methods as well, but I'm personally not a fan of any of them. For blow-through I would do what TxFireman1972 said.
 

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Discussion Starter #13
Wow. That last post clarifies what I need to do. Thanks. I am using a draw through maf. 2 last questions. Should I stick with my sealed oil filler cap and not run a breather in place of the oil fill cap? And the other thing is I am using sve aluminum valve covers with no baffle on the underside where the bottom of the oil filler tube is. I believe I didn't put the baffle in because of interference with trick flow 1.6 rollers. I think this is going to cause a lot of oil to get sucked out of there from that nipple off the filler neck. I still have my stock valve covers and was able to unbolt the baffle from it but haven't removed my aluminum cover yet to see if the baffle can be installed and if it can if it will interfere with rockers. If i have to switch valve covers is there a decent looking one out there that has a baffle under the oil filler pipe that will clear rockers? I am running a 1 inch spacer between upper and lower intakes at the present time.
 

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Use sealed oil cap. A breather will introduce unmetered air.

The catch can should catch any oil that the absence of a baffle allows into the line.
 

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Discussion Starter #16
Do you have a suggestion on how to attach the end of the hose coming from the catch can to my anderson power pipe? It will have a pro m 80 on the end of it tucked in the inner fender. There is no provision on the power pipe in which to attach the catch can hose.
 

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Discussion Starter #17
And do I not use the check valve that vortech includes? It looks like a silver gas filter supposed to go from oil fill nipple to their plastic airbox (which I won't be using)
 

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A lot of Powerpipes I’ve seen have a nipple on them to attach a fresh air line. If yours doesn’t you could drill it, put a grommet in the hole, and then push in a barbed fitting that fits tightly in the grommet. There is no pressure on this side so it shouldn’t blow out.

I’m sorry but I’m not familiar with the check valve Vortech is supplying, but if you set it up as I described you shouldn’t need it.
 

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Discussion Starter #20
So the guy I have been working with at anderson ford said to install the barbed FITTING into the air filter itself on the front side which will be before the maf. What size hose i.d. would you recommend for the hose from oil fill pipe to can and can to barbed FITTING? Probably gonna be around 10 PSI
Also can I just leave the pcv as it is to the back of the upper intake relying on the pcv valve to close under boost or is there a better way?
 
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