Ok I have read over countless threads on here and have failed to answer my question so here it goes...

My supercharger installer is installing check valves on my PCV lines to prevent over pressuring my crankcase etc, that being said I am debating on whether or not to drop the $$$ on LMR's breather/catch can setup.

I am pretty sure I'm going to need a catch can regardless however I am looking for some of your opinions on whether I really need a breather or if the check valves should be sufficient. I am aware that positive crankcase pressure will still build up from piston blow by but is this alone enough to warrant spending the cash on LMR's unit?

Thanks in advance guys.

 

Anytime you can remove the input lines to the intake (even the fresh air lines become input lines under boost) then you are doing yourself a favor.

The best solution is a vacuum pump. But since that won't work with a supercharger on a Corvette, LMR can is the next best thing.

 

Thanks for the reply, thats the answer I was afraid I was going to get.

I'm not terribly opposed to the price of the LMR can but I am really NOT fond of the idea of pulling my valve covers and trying to weld the fittings on there... Sounds like an epic PITA and I only get to play with my C7 for a few days every other month so having it torn apart those days sounds like a buzzkill.

 

That is why we implemented our Valve cover exchange program. You pay a core charge and a small fee up front for us to weld fittings on a set of valve covers and ship it with the catch can. Then when we receive yours back we refund you the core charge back. That way you have no down time other than the time your installing everything. No waiting on people to weld your valve covers up because we did it for you.

Let me know if you have anymore questions

-Reid
713-466-9900

 

Ooo, please do something about this soon & be careful driving her until you feel confident you've achieved a good balance between evacuation & fresh air supplied. Also consider looking at the intake system to see if you burping any oil after track use or anytime you drive it hard.

Wormwood

 

This was, by far, the worst part of having this done.

Now that LMR is offering this, it's a no-brainer (in my opinion, of course).

Also, for those wondering about going back to stock, the valve covers are under $150 a piece - nothing serious there.

 

My question about the breather system is this. I understand that under boost there is suction being created, which is great on a race car where the majority of time is under boost. But what is causing suction when the car is not in boost, which is what the majority of driving in a street car is? Has there been any tests done on a breather to see what type of vacuum is being created in normal driving conditions ?

 

Are you asking if it's causing a vacuum leak during normal driving?

 

No. Is the breather pulling enough fresh air in during normal driving. A PCV system is applying constant pressure/suction into the system, boost or no boost. I don't understand where the airflow is coming from in a breather system when the car is not under boost and under pressure. There is a reason PCV systems are on cars without boost. The majority of the time our cars are not under boost.

As an example, if you have a house filled with smoke and you open a window on each side, you I'll get a little bit of circulation and smoke will trickle out.

But if you put a fan on one window, the smoke will clear out much quicker.

So what I'm wondering is has anyone taken a pressure reading on a breather system tube when a car is not in boost? How much crap is circulating out?

 

Totally understand what you're saying.

At idle, there is suction coming from the filters - not a lot, but it's enough to feel air moving.

Reid could answer this a lot better than that pathetic anecdotal attempt, though.

 

the answer to your question is no. that's why a vacuum pump is the best solution. with an open breather setup, you are choosing....and you must choose....the lesser of two evils.

on one hand you are keeping dirty air out of the intake and off your dry DI intake valves but on the other you must change your oil more frequently and deal with the possibility of long term (100k+ miles) effects of more contaminated oil in the crankcase.

so where do you want the crap? in the oil pan or on your intake valves? most choose the former.

 

What is the difference between the PCV system/catch can and a vacuum pump? The suction pressure?

 

pcv system uses intake manifold vacuum behind the throttle body to actively remove air/pressure (and as a result moisture and contaminants) from the crankcase. if it were sealed it would not work/leak/cause issues so a fresh air line allows metered (by the MAF) air to pull through the system from the intake tube in front of the throttle body, into the valve covers and down the oil system, and into the crankcase to balance the intake vacuum pulling from the oil gallery under the intake manifold and into the intake manifold itself. the problem with this setup is that the next step in line for dirty air to go is over the intake valves. this makes them dirty. really dirty. the other issue is that under times of extreme pressure, like under boost or in older ls motors, high rpms and cornering, oil could push backwards out the fresh air lines into the intake tube....sort of like what is happening with current dry sump lt motors.

a vacuum pump, powered by a belt driven pulley, with the tubes and nipples from the stock pcv system sealed, actively pulls air from the crankcase through the valve cover fittings or oil cap hole or oil galley fitting or all of the above depending how it gets set up. this creates a measurable and adjustable constant vacuum in the crankcase. when it is pulled out it is vented into a catch can similar to the lmr product on hue he market today. check out www.gzmotorsports.com for a good example of what I used on my old Z06. they have no product for the lt motors yet but there are other companies out there too. a vacuum pump can free up real horsepower, like 20-30 in many cases by removing the resistance on the backsides of the pistons during their motion.

the lmr solution allows the crankcase to passively vent when pressure in the crankcase get high enough to need an escape and hopefully prevents the oil gaskets from leaking due to pressure.

 

This was my original hope, but there's not been enough demand for them to come up with something for the LT1 yet.

 

I think I'm going to roll with a standard catch can for the time being, what I find in said catch can after say about 3000 miles will determine if I am motivated to drop the $$$ on a fancier setup...

Any recommendations on a catch can? I am impressed by the Mighty Mouse setups but they appear to be on back-order for an undetermined amount of time.

 

Actually I spoke to GZMotorsports a few weeks ago. He didn't even realize the new Vette had a different engine so R&D hadn't started. If a bunch of people call over there and say "need an 2014 Corvette pump" then he will do it. It's just a different bracket, don't need a whole new pump/system.

The only catch can that is guaranteed not to allow anything into your intake (which is the entire point of one) is the one that does not apply vacuum to the can from the intake manifold.
Finding something in your catch can does not mean it is working, it means something is traveling through it.....every catch can I have had that is simply stuck in the stock routing still ends up with oil in the intake. With that said, so far on the LT1, bone stock I have had no oil residue in my intake manifold or the lines that go there so IMO nothing is needed until you have boost.

 

I've seen about 15 different catch cans cut open to see what is inside. I would recommend RX or Elite. After seeing them cut open the Mighty Mouse would probably be one of my last choices.

 

The big difference between what is normally considered a catch can and what I would call a breather system is one keeps the integrity of the PCV system by maintaining the function of it but providing an additional process to seperate the oil from the air path. A breather system does provide a method of seperation but does NOT plumb anything back into the intake and vents to atmosphere.
Its a pure venting system. Pretty much with the engine running there is always blowby of some sort so despite the fact that gm does put some of the vent lines into the air inlet plenum they are not for clean air intake so much as for PCV overload but still acting as a closed system to allow the engine to burn all the vapors coming from the crankcase.

 

He is planning on boosting his car. I have a catch can and I've been boosted for Several months now. I've drained mine once so far and my Catch can and is catching stuff that would otherwise be going back into my engine/oil. Am I saying it's catching 100% of the stuff? No, But I do know it is working.

 

I agree that it will catch "something." If you look at it that way then the lines are "catching" some of it too since they are oily inside.

The real solution is to block off anything connected to the intake, otherwise it is only prolonging the inevitable.