binder, str8dum1 runs just two breathers with a drilled out PCV and it's worked for him all the way to 1000 whp. It would let out fumes at idle though - so just saying - it might be a little stinky.

jumbosrule is correct about emissions, which is one reason to just keep one breather out back under the neck of the plenum where it cannot be seen.

 

I heard it before and it's 100% wrong. The VQ25DET is already turbo in Japan and used since 2001 at the same time the VQ35 debuted.

It was engineered and intended for both NA and turbo applications. You don't mean to tell me that a motor capable of holding 1500bhp is somehow just a really big coincidence. What other V6 have you seen presently that can compare in versatility and potential? None.

 

cool, good to know. I've had it with a breather on the drivers side for a year and then i converted both sides this spring. I haven't noticed a change in smell in the cabin at all so i'm not concerned about it too much.

and indiana has no emissions missouri does but i'm plated in indiana so they can't touch me.

 

In addition, not only the 2.5 but the VQ30 came turbocharged since the late 90's (DET), which is the closest thing as far as design to the 3.5. (I know, i have 3.0 and 3.5 parts all mixed together in my motor lol)

 

Read this entire thread buddy...You sound like you know what you're talking about so catch up on our experimentation and feed us input. Because at this point there is no expert on this topic regarding a boosted vq35.

 

+ ten million

exhaust CC vent.. thats where i want to head. I still have a bit to learn/prove/confirm.

 

Binder! You and I have virtually the same engine so your input is crucial to my divide and conquer results.

So.. You have 2 breathers where? Diagrams would really help in this thread.

The stock pcv only does one thing (for our intensive purposes). Creates a vacume in the crankcase. Opening the pcv will increase vent volume at the expense of vacuum. Dont consider the pcv as a vent for the crankcase. That is not its purpose! There are other paths for CC vent available. I wish you guys would read the links I posted, because the fundementals of physics dont change. Only trying to apply it to the VQ35now.

Binder: "So I would be ok with drilling out the pcv valve if i have just a breather, correct? "

If you are going the route of venting only then I would suggest Streetlegendz method. His way as I see it is the best way to provide an open vent for blow-by to release. I want both though...

 

Wow..where did this ignorance get injected, you're thowing me off!

If you Mr. Andrei think that the stock VQ35 induction, exhaust, internals, AND CC plumming (which is the topic here) can handle 1500 hp you have your di@$ in the dirt.

Sorry guy, we're not running the VQ25DET here. I'm just doing trial and error here based on numbers and other intelligent input. This is an old thread and you should start by reading "Binder, Rcdash, and Streetlegendz" input before you come at me. Honesly im new to this engine and FI in general but, I am providing useful info. So, read up Then talk to me ...

Anyways, where was I?

 

I 'm thinking about leaving the PCV there and run it like this:

PCV---->catch can----->plenum

driver side valve cover----->pre turbo (in the GTM TT kit the pre turbo nipple is before the MAF not after it like the oem)

just like the stock way.

 

I've done a TON of learning about this topic. Plus I'm a NASA engineer of 14 years so I absorb tech pretty well. I did read the entire thread, but just picked recent posts to quote and talk about. I've spent a lot of time here and on the G35 & FX forums, looking at VQ catch cans. The concept really isn't difficult - what's confusing are all the different variations. Which one is "the best" way?

I'm sort of saying the same things again, but maybe in a different way. Sorry y'all for rambling - it's an engineer thing.

The whole purpose of crank case ventilation is to remove blow-by. If no blow-by were produced, crank case ventilation wouldn't even be necessary. Blow-by = contamination and it is one of the major causes of engine sludge. The Valve covers, Crank case and oil pan are all connected and open to each other. Blow-by gasses circulate freely through and between these areas.

Naturally Aspirated: Blow-by in any one of those areas will eventually evacuate through the valve cover, into the plenum due to the suction from the cylinders. Blow-by does produce positive pressure, so it is pushing out of the crankcase while the suction hose is pulling it out at the same time. This is why a breather with no suction hose can still work - the system is relying on the positive crankcase pressure to push out the blow-by gasses.

The absolute best catch can setup for the NA VQ IMO are two catch cans - one filtering blow-by gasses from each valve cover. Both routed to suction. Use OEM hose sizes and match the catch can fittings. Nothing inside the can should restrict the flow of gasses and there should be some type of filter media in the can.

Forced Induction: there isn't suction from the plenum anymore - now there is pressure (boost). Crank case pressure is still positive, but now the plenum can't be used as a suction source because it is at a higher pressure than the crank case. A breather can still work in this application, BUT a boosted engine produces more blow-by than an NA engine. IMO, breathers should not be used on a boosted street-legal car. You want suction and a catch can to separate the contaminants out so they don't stay in your crank case or collect as sludge inside your air charge pipes.

Once again the best catch can setup for a boosted VQ is going to be two catch cans, one on each valve cover. Suction comes from just behind the air filter - before the turbo/SC.

There are a TON of other ways to do this. Single cans, check valves, additional vacuum pumps, huge reservoirs with multiple breathers, tapping new exit holes in the valve cover... but IMO the setups I described are the best for a street legal VQ.


Not sure why you want to go this way?

Would you have a catch can in this system or would you just be routing the crank case vents straight to the exhaust pipes? No real benefit to this approach. Not much better than a breather - could be worse, environmentally.

 

I have a filter on the pcv valve and on the vent on the back of the drivers valve cover.

PCV port definitely does expell crackcase gases when under boost. It's a great vent for pressure.

I'm not putting a vac source on anything because i'm not sucking those gases back into my engine. I'd rather them just going to the atmosphere. Plus all the additional mess in the engine bay that is already cluttered.

so far i've had no problems just keeping the 2 open breathers. I don't even experience the nasty smell some say they have.

 

Plenty of track cars are set up like this. Some don't even use breathers - just a screen. There should be zero performance problems with this setup.

I would not expect you to smell anything inside the car. Only outside the car, while it is running and the gasses are moving through the breathers.

If you filter the air (catch can), then sucking the air back into your engine doesn't matter. If it is not clean air because it is not filtered - I agree, keep that crap out of your intake!

 

Exactly. That 2.5 in Japan is a direct swap in parts and internals and in particular the valve covers which are made different on the 2.5 for the turbo.
The obvious escapes you. Of course it will only hold 1500 built.

 

there lies the problem though. a catch can is the furthest thing from a "filter" that one could ever get. All it does is pull the gross contamination of oil out of the air by condensing it. THere is still plenty of oil suspended in the air along with all the chemicals that are in the air.

Smell the inside of your catch can, all that nasty smell is still mixed in the air particles and bad for your engine. Catch cans don't stop emissions, they only stop the large molecules of oil.

one would have to run a true inline filter on your hoses but that would be restrictive.

 

That's the way I had it when my intercooler filled up with oil. (stuck PCV)

 

On side note. I want to thank everyone here for their input. This really is a great thread.

 

Just a quick one guys, Ive just fitted a catch system to my car yesterday. It uses a twin can system that goes: PCV----->catch can----->Plenum. 2nd can is routed from the valve cover balance/cross over line-----> catch can ----->10mm one way valve ---->vent to atmosphere.

This system should give vac at idle and cruise (anything off boost) And vents out to deck when in boost.

I may add some vac/pressure gauges to the catch cans and try and record what pressures there seeing.

 

If you're not concerned with emissions or smell, then why not pull the crossover hose connecting both valve covers and add 2 more breathers? In effect doubling your crankcase venting potential.

Last week I was trying that out. 4 breathers total. 2 on each side. I did notice that my valvetrain suddenly got louder. Especially at a cold start.

Why, I dont quite know. Leads me to suspect that somehow vacuum in the crankcase at idle is aiding in oil lubrication or in sealing something. Things were just rattling around quite a bit more up top. According to my ear.

 

Jumbosrule! What you think about this? As of a few days ago this is my current setup.

I can't quite explain why, but my engine is the happiest its ever been like this. The red indicates a one way check valve.

I think this engine is liking vacuum traveling all the way through the bottom of the crankcase. Which I achieved by severing the crossover hose linking both valvecovers.





This method from a performance standpoint, Zero blow by is being recirculated into the intake at wide open throttle. Thus, never contaminating the air/fuel intake charge when my engine is trying to make power.

When I let off the throttle, yes the air/fuel intake charge is slightly contaminated (because catch cans are not 100% effective), but I dont necessarily need a 100% pure air/fuel intake charge when I am throttle off. What I am gaining though is a vacuum inside the crankcase which I think my engine internals are liking (wear and tear wise).

If this were a track only car, I would never consider recirculating crankcase vapor back into the engine. But track cars are, mostly never sitting at idle and certainly not concerned with wear and tear.

Does that make sense?

As far as my interest in using the exhaust pipes as a vacuum source (bernoulli's principle) to create a vacuum in the crankcase is this: It is the only available source where when you step on the throttle more, vacuum increases as opposed to decreasing, AND unlike the "pre-boost" vacuum source doesnt recirculate dirty vapor back into the intake.

djtimodj: You have same idea as me. All I ask is: Why put a catch can to filter crap that you are just venting to atmosphere anyway? Just put a breather there, or 2 (like me), one on each side. Pull the crossover hose altogether.

All in all I have 3 breathers total. And I have never altered the stock valve cover moldings.

 

Putting a filtered/baffled catch can before the breather reduces the oil spray in the engine bay and the burnt oil smell. The exhaust gas vacuum source has been used by others but with mixed results reportedly (similar to the weak findings found on preturbo intake as a source). This may be because of improper implementation though. Too much effort when an open breather suffices...