Ffim catch can advice.

[kotu100]

7mgte catch can setup with ffim
My car just had a bunch of stuff done at a local shop. One of the things they did was the catch can setup. Currently the lines are going right from the valve covers to the catch can. I asked them to put a fitting on my intake pipe, run a line from there to the catch can and tee the two lines from the valve covers into the other fitting on the catch can.
They told me that since my motor is fresh with minimal blow by the way it's setup now will be sufficient.
This shop does a lot of work on the 2jz and I always see those hooked up the way mine is now, however in my extensive research on the subject I find that the catch can NEEDS a vacuum source to work properly.

So should I listen to their advice or should I ask them to add the fitting to the intake and run a line to the CC?

 

[IBoughtASupra]

I've hooked them up with no breather, two lines going to the valve covers and one pre turbo. They work fine.

I know you are supposed to have a vacuum line from the intake with a check valve in it as that's the way its done if you go by the book.

I believe Habanero had a thread about this. Take a look.

 

[kotu100]

The way u describe is what I was asking if I should have them do.
Currently it is hooked up just the valve covers to the catch can.
I'll look for habenero's thread on it.
With the amt of money, time, blood, and sweat I have into this car I want to make sure it's done the right way.

 

[IBoughtASupra]

Does there can have a breather on it?

Baffling inside the can? Doesnt matter how you hook a can up, if it isn't baffled, it will not work.

 

[kotu100]

There is a breather, in fact that's how I have to drain it...
Turkey baster thru the top or I have to completely remove it. No baffles at all!

 

[kotu100]

Bump, would the vented catch can straight from the valve covers be fine?

 

[toyotanos]

The way I would suggest setting it up would be the way mine will be set up. I am using one of Andy's cans and I will say it's a good unit- a bit pricey, but for something that works I can't complain.

The way I have it set up is like this:

There are 4 ports on the can- there are 2 1/2" side ones which are the inputs from the valve covers, the opposite side 5/8" one is the output, and the 1" top is going to be the vacuum/boost supply. Vapors go into the can through the input lines and go through a baffle to help seperate the air and vapors. Then the top port will have a PCV valve providing vacuum at idle and boost under power, helping move the gasses through the can into the output port into a second can which should catch any remaining liquids before dumping into the tubo inlet.

Its been done as a simple vented system on many cars, but its no longer PCV, its only crankcase ventilation. Since we want positive movement, the port on the intake provides gas movement- whether into the intake or out of it. You have to think differently about a boosted car as opposed to an NA car- we have to have a 2-directional PCV system to compensate for the positive and negative pressures in the intake.

 

[kotu100]

So what about the 3 port cans he sells? 2 for valve covers and the other for boost/vac source?
I only see 3 in your pic. Where is that red line going?

Isn't PCV Positive Crankcase Ventilation? With a vented catch can wouldn't the positive gases be vented? What is vacuum needed for?
I'm just trying to understand this better.

 

[toyotanos]

The red line goes to the air filter pipe, after going through a secondary catch can. (trying to keep as much oil/water out of the intake as possible) The 1" port is on the top of the can (has a green sponge in it, in the picture)

The idea of the 'positive' is that there's somethig else moving the gasses.

Think of it like this: if you just put a little air filter on the valve cover breather, what is moving the gasses out of the engine? Answer: crankcase pressure. The gasses are still moving, but since you want as little crankcase pressure as you can, you want another force move the gasses.

If you look at the stock setup on a turbo 7M, there' the pipe that connects the throttle body pipe to the breathers on the valve covers, and then that all dumps to the intake tube. All you're doing with a catch can is adding a reservoir for the condensed vapors to go, where the gasses and air get ingested into the engine under all operating conditions.

Here's the way it works:

At idle, air is drawn from the air filter housing, past the valve cover breathers (which draws gasses out of the engine by the air movement) and into the inake to be burned.

Under boost, air comes from the throttle body pipe and mover through the tube past the valve cover breathers (which draws the gasses up via air movement) and then into the turbo where they (eventually) get burned in the engine.

The only time there isn't positive movement is when intake pressure is 0, but that's a rare condition so its usually overlooked.


The main reason we install a catch can is to keep oily residue from the PCV system from collecting in the intake/turbo/intercooler systems which is messy and can reduce efficiency. The better a can is designed, the better it will seperate the gasses from the liquids, and it will collect them for later disposal.




*Disclaimer: this is the way the system works as I see it. If someone smarter than me knows better, please let me know so I can better my knowledge!

 

[kotu100]

That makes sense to me.
If I understand correctly I would need to have a sealed catch can with lines going from valve covers to catch can. Another line with a check valve or an orifice tube from the intake manifold to catch can to supply vacuum when not in boost. Lastly a line from the intake pipe before the turbo to the catch can to provide air movement when under boost.

 

[toyotanos]

Yep, sounds like you have the right idea!

 

[kotu100]

Any idea where I might find a check valve. I found that IJ is using a "fuel miser 102" metal PVC valve but I haven been able to find a source on where to buy them. The only other check valves I could find we're fuel check valves. Not sure if that would work. I saw the way nashman has his system hooked up and that's what I'm going for.

 

[toyotanos]

You don't want a check valve, a PCV valve will work correctly. You want flow in both directions through the intake manifold hose. Just look for a PCV that fits your application. In my case I'll be running a 1"-> 1/2" coupler at the catch can, then running it over to the backside of the FFIM, then a PCV plugged into that hose then into the intake.

 

[kotu100]

So I could use just any generic PVC valve?
How about if I were to tap the ffim and install one like in the link below?
http://www.thepartsbin.com/catalog/...X&ei=4T0tUIHkHeuy0QGnyYF4&ved=0CIoBEIMIMAc4Cg

 

[toyotanos]

Not sure if 'just any' PCV valve would work, I suspect that's why IJ used that specific metal one(but I'm still not sure). More research will be needed to find the best answer, I think.

 

[IBoughtASupra]

If it seals when boost hits, I don't see why it wont work.

 

[toyotanos]

Because you always want movement in the system. If you only allow vacuum to suck stuff in, what is there to help the gasses move during boost? It ties back to where you don't want *only* crankcase pressure moving the gasses. Just lie the factory did, letting a little flow reverse back through the PCV system allows it to do its job better.

Intake pressure/vacuum moving + PCV vapors = positive crankcase ventilation.
PCV vapors + crankcase pressure = crankcase ventilation.

One is better than the other.

 

[MarkIII4Me]

So how much of a boost leak will you get from running a pcv from the ffim? Won't this cause problems?

 

[toyotanos]

You run a restrictor into the manifold, just like the factory throttle body had. It is a small leak, but since its going back into the intake system after the MAF it won't mess up your MAF signals/AFR's.