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Crank case ventilation idea


wigenOut-S30

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I was talking with Joe over at Arizona turbo (where I got my new Garrett turbo) today about a oil restricter for my new turbo. He recommended me not restricting the oil to the T3/T4 turbo because if you restrict it too much you will burn up the bearings.He did state that in some cases it might need restricting but no less really then 100thou. or 3/32. He was asking about crank case ventilation and how my setup was. I told him I had the breather on the valve cover as well as the crank case breather. Both are going to atmosphere. He suggested hooking the crank case breather into the down pipe at a 45deg angle. This will put a vacuum on the crank case, and oil will flow out of the turbo much better and probably even pick up some HP. Same concept of running a PCV but you wont have oil mist going through your intake manifold, engine and exhaust side of the turbo. So what do you guys think? has anyone ever done this in the exhaust?

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So is this another example of a myth of 'beneficial backpressure' is debunked once again???

 

sounds more like an effect of venturi suction with the pipe at 45 degrees to the DP than negative backpressure. Exhaust rushing past to get out the tailpipe drags the crackcase air out and along with it.

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So is this another example of a myth of 'beneficial backpressure' is debunked once again???

 

Not necessarily, even with a pressure in the exhaust, say 1.5psi, the atomspheric pressure will be lower causing flow and the gas will have velocity. The flow over the orfice will still cause suction (see Bernoulli Principle), but it wouldn't be as much suction compared to a system with a higher pressure difference between the atmosphere and the cylinder (ie. no pressure in the pipe) causing a higher egv.

 

So, I would have to say that actual backpressure has no bearing on the system, but egv does. ;)

However, backpressure and egv are inversely porportional, so an argument could be made that backpressure does play a roll, especially in a situation (if this is possible) where the backpressure was higher than the crankcase pressure, bringing a reversion of exhaust gas into the crankcase.

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Er, the evacuation of the 45 pipe in the exhaust will reduce crankcase pressure buildup. I can show you pipes in a 100psi header with a vacuum on them relative to atmospheric pressure due to the velocity in them. I doubt the pressure in the exhaust post turbo would be 1.5 psi...maybe 1.5" water column but with the velocity across the orifice a great pressuredifferential (suction) would be available... But the reference was to crankcase pressure buildup.

 

A.K.A. 'Backpressure'...

 

Some guys promote no PCV system under some misguided belief that it doesn't have any positive effects. Akin to some people believing 'some amount of backpressure in the exhaust is beneficial to the low end power production'...

 

I guess if you have to explain the joke to the audience...it was probably flying too high anyway. Sorry Guys, I thought it was witty at the time.

 

Apparently not.

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I guess if you have to explain the joke to the audience...it was probably flying too high anyway. Sorry Guys, I thought it was witty at the time.

 

Apparently not.

 

You make a 'joke', then when people want to discuss the issue with you, instead of patting you on the back for the 'joke', you speak to them with a condescending tone. I don’t understand this.

Maybe I'm not witty enough?

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Im planning on running my crank and valve cover vents to one of these. Is there some ideal size of pipping i should use? im planning on doing it under the car after my dp goes from 4" to 3" so it should have a higher velocity. Another question is how long does it have to be straight before i put another 45 in it and make it run parallel to my exhaust? And can i have both vents going to one pipe or do i need to use 2?

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