Blowby: how much is too much?

[adampecush]

So I made a modification to my PCV system at the request of my tuner, which basically eliminated the vacuum port from the intake manifold. Since then, I've been blowing oil into my turbo intake pipe to the point where the air filter leaks a pretty good deal of oil. I imagine the low intake pressure and cooler temperature resulting from a large air filter and large diameter intake pipe are causing vapor normally sucked into the engine to condense in this area.

I have a catch can on the way, and I will also be tapping my valve cover for a DSM PCV valve (for the sake of cleanliness). I'm hoping this will clean things up, but anybody else have any other pointers?

The car doesn't smoke on accel or decel either. I'll also be going up in oil weight shortly to see if this reduces the condensing blowby at all.

Compression test is the next step...

Any comments/tips/pointers are welcome.

 

[GrimJack]

Why did your tuner want to mess with the PCV system in the first place?

Technically, it's not too much until it starts to collect in the intercooler... eventually, it will plug the bottom of the IC and reduce it's effectiveness. I've seen cars with bad blowby where the IC had 2-3 liters of oil in it.

Compression test will tell a lot more of the story, too.

 

[adampecush]

We were trying to diagnose why the car was dropping boost above 5k. He said leave it out...

The way it was hooked up looked rather ghetto though, tapping a valve into the valve cover should clean things up.

I suppose I should take a look in the IC. So far, the vapor seems to be condensing before it even gets to the turbo. We'll see though.

 

[IBoughtASupra]

Here is what you should do.

Get a catch can, run a line pre-turbo, meaning your intake pipe to your catch can. Then run a line from each valve cover to the can on it's inlet side, some choose to "T" the lines for the valve cover into one slightly bigger line and run that to the catch can, that is fine too.

Now the question is, how good is your tuner? I have never met a tuner wants to remove a PCV valve.

Also, where did you get your catch can, I hope you bought a good quality one and not one from EBay which is just a piece of foam that does nothing, hence why some never find oil in their can.

Have you looked at my catch can thread? Take a browse, you might like something you see.

 

[adampecush]

My catch can is on its way. Saikou Michi catch can, comes very highly recommended.

Tuner was Justin Nenni. Probably one of the best out there. Like I said, we removed it to eliminate it as a potential cause of the boost "leak". I decided to leave it off to see if I could get away without it when I installed my turbo.

 

[GrimJack]

Ya, makes sense - I pulled that line on mine once the boost went up significantly as well. Do the compression test and get back to us.

 

[IBoughtASupra]

O, well now that you said it is Nenni, then it is understandable but make sure you do your catch can right and don't vent it, use a line off the intake pipe infront of the turbo.

Also, the higher the boost levels, you really shouldn't have more blow-by. How much boost are you running and was your engine built with the wider clearances to allow for the higher boos levels?

Usually when the rings are gapped wider than normal, it will cause blow-by when the car is cold and lessens as the car warms up and even less when the rings expand due to thermal expansion where boost pressure helps in that process.

Anyone who knows better, you can correct me, no sarcasm intended, just trying to be informal and do it correctly.

 

[adampecush]

sad face.

150 149 145 148 152 115.

Added oil to #6 and got compression up to 125.

I guess this explains both the blowby and the slight miss in the idle. Fuck. Rebuild time.

edit, upon further consideration, I will check #6 valve clearances. If they are in spec, I'm going to beat this motor like a Sunday morning hard on until it gives up.