Which style is better for a dual breather set-up?

Aims:
1) Proper function
2) No mess
3) Lifespan

Valve covers have Moroso baffled grommets in them already, and breathers will be push in style of these two types:

Open element:


Closed element:


Moroso grommets:


Thanks

 

I think you are likely to hear that to meet all three of your goals that a PCV system is what you want.

However if you must run dual breathers by all means run open element, only because it looks tough - no functional difference either way so far as I know between the two options you offer.

 

my closed element always weeped small amounts of oil, i finally went back to the stock PCV set up

 

OK. I'll say it: To meet all your goals, a PCV system is what you need.

Why? Because the PCV system clears all the positive-pressure gasses from the interior of the engine without exposing them to outside air. It 'draws' that engine air out of the PCV valve and into the carb base for burning along with the other fuel mix. Just run a vent hose from your air cleaner [interior] to the right-side valve cover and put a PCV valve in the left-side valve cover with hose running from it to the "purge" fitting on the baseplate [front, usually] of the carb. If you have a fuel vapor canister, the purge from that device can be "T-ed" into the outlet from the PCV valve before running to the carb base.

This keeps your engine compartment free of oil vapors, and is much cleaner as a result. There is no loss of performance resulting from the use of a PCV valve.

 

It needed to be said...

 

I agree that there's no reason to run open breathers on anything other than a race engine.

 

open breathers will also make a oil mist, mess out of engine compartment.
do it the right way PVC.

 

also watch out for those aftermarket grommets,
I just finished chasing a problem on my motor, with building up crankcase pressure,
even tho I had a complete fully working PVC system in place.
after checking everything twice, I finally found the Grommets were way to restrictive /closed... stopping the PVC system from working.

 

I think u want to adapt something to your Edelbrock Pro Flow system that i see in your profile. Yes? I imagine Edelbock left you without a PCV connection. Well a lot of big camned cars don't have much vacuum at low rpm and its hard to match them for correct PCV. PCV is kind'a calibrated to reduce flow at low rpm/high vacuum - so it don't suck oil out the vlv cover. Then open and pull like hell at high rpm to pull out the "blow by".
Now for your Edelbrock Pro Flow system i read u need to improvise something to prevent over pressurizing the crankcase. Yes? A possible effort would be to choose either open or close element rather than to plumb into the intake downstream of aircleaner for filtered air. This will provide a "filtered air source" for the crankcase. U may see some oil smoke after shutdown as some blow by drifts up and out the vlv cover vent (and some trace oil around the grommets too).
Now u can plump something from the crankcase - vlv cover or even the lifter valley from under the intake if u dare drill. And connect the other end to a low pressure source (lower than atmosphere called vacuum) in the intake plenum (uncontrolled vacuum leak now unless u install a PCV vlv), upstream throttle body (again uncontrolled vacuum leak w/o PCV vlv). My choice would be an vacuum pump installation like a lot of drag cars use - some use a Ford smog pump reversed to pull crankcase vacuum.
Dragsters also use a exhaust induced low pressure connection at the header collector but this is really only effective at higher rpms.
I don't see a airflow sensor on the Edelbrock Pro Flow system so that should be one less item to deal with here.

So i can see where u what to run just dual breathers here Chris, and good luck with whatever u choose,
cardo0

BTW nice work on your Pro Flow installation cool dyno numbers.

 

If it's closed , it's not a breather.

 

Wow wow wow. You guys are awesome. Thanks for all the replies, I need to hang out here more often.

Ok...

First off, while I had made attempts at keeping it a street car. I'm really lying to myself about it, it is a race car... just not as well prepared as I would like but that is in progress.

Second, its good to hear these opinions on the PCV vs breather. While I do believe that the air in the crankcase is probably not nearly as rich in oxygen as the fresh air (nor as cool) I understand we are probably only talking 1-2 hp here so not a deal breaker I suppose as I probably have more than enough already. (And I still have a 280 XFI cam sitting on the shelf which I don't know if I should sell or install...)

I didn't want to bias people but I do actually have a PCV system in place now. It does *seep* (when racing it gets visibly wet with oil around it) oil on the valve cover by the PCV valve (which passes the blow/suck/yuk test and is about 3k miles old). It hasn't spit the dipstick out yet and I was having VC gasket issues but a set of permadry's has seemingly taken care of that for the time being.

My current setup is this:
Pass side VC grommet goes to the air intake in front of a mass air flow sensor (an attempt at making the PCV a controlled vacuum leak).

I took a spare vacuum port (and yes Card0 the line routing is a bit creative...) but it runs over to the driver's side VC where it connects to a PCV valve with the grommet in place.


Now my motivation for running breathers was really this:
1) Engine sucking only fresh air for HP
2) Hopefully resolving the weeping oil out the grommet by the PCV valve
3) Cleaning up the engine bay and removing the lines going forward to the intake to meter the PCV draw as I've got them zip tied out of the way but they want to be too close to the throttle blade than I like
4) Reduce chances of fouling MAF sensor with oil mist

It seems the majority really likes the PCV method. I'll have to think on this a bit more but I really appreciate all the comments.

 

If you are racing the car, the engine is producing a LOT more engine fumes internally than it would do as a street engine. The PCV valve you are using (if 'stock' for your engine) is likely not large enough to handle the excess, nor is the feeder hose or nipple on the carb base. If you don't use the power brake vacuum connection at the rear of the carb base, you might want to try running a larger PVC hose to that fitting and see if it helps. Also install a PVC valve that is made for the largest displacement engine you can find (6-7 liter displacement); it might have enough capacity for your needs.

 

I wanted to comment on this - the PCV valve dilutes the intake charge in a very trivial way. Unless the engine is making > 1.4 HP/CID, you're not going to see a difference on the highway.

Check what other racers in your class are doing - may be that a catch can or other approach works and/or is required. Some classes won't allow open breathers.

 

The hoses are bigger than stock but the PCV valve is stock. I like this idea, similar to what card0 referenced too. I may try this first.

Billa, I agree, thats why I said it was worth minimal power above and it is only a fraction of the motivation not the entire motivation alone. However it is about 1.3 hp/cid with the small cam. I do think it must say something that everybody here is so on-board with the PCV plan.

 

1.3 HP/CID...nice Pics!!

 

Regarding the first two numbered items:

1) No fresh air will be allowed into the crankcase unless you run a functioning PCV system (or vacuum pump, or evac system to your header collector(s). Blowby, which all engines have to a degree, pressurizes the crankcase a bit preventing fresh air from entering the crankcase unless you create some sort of flow. A bit of vacuum in the crankcase is good for HP,..but the biggest reason for a PCV system is to remove harmful blowby gases which will crude up the oil and can cause premature oxidation of internal engine parts.

2) There's a huge variance with grommets and their effectiveness at sealing off oil leaks. They're cheap and readily available. Find two or three different sources for grommets to find something that works.

 

If it's more race why not consider a remote breather set up? This is mine.

 

I look on summit for breathers and all I find is this http://www.summitracing.com/search/M...ase-Breathers/

 

wow that looks great i am not sure i can follow where all the tubing goes and is there a pressure gauge on it or am I looking at a different mechanism....does the tube that goes by the overflow cannister loop around to that silver solenoid looking thing with the pressure gauge? what is that? thks bob

 

Thank you. The line comes off the driver valve cover, loops around the back of the motor to the T fitting u see in front of pass side hood latch. Then the pass side valve cover loops under the pass fender to the T as well and then to the breather.
The solenoid thing with the guage is the Deadhead regulator for the carb.