Crankcase pressure issue - Mazda MX-6 Forum
 
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post #1 of 11 (permalink) Old 7-13-16, 8:26 Thread Starter
 
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Crankcase pressure issue

Im at the point now that im tackling the crankcase pressure issue, right now i have 4 vent of the valve cover , but i notice under high boost, they are not sufficient enough to get right of all that air.

so basically up to 26psi... its good enough.
but at 30-32psi, seems like im forcing too much air into the motor that need to be vented fast. I might need to incorporate the moroso vacuum chamber to aid with sucking the excess pressure out fast or vacuum pump.

Whats you guys take on this issue?
By the way this is on the red probe with stock motor and hx35 turbo

I made couple of changes to the car from last dyno day
made 501whp on 30psi
swapped out 8 blade hx35 to 7 blade hx35
add 1 extra valve cover vent
now on high boost i see up to 32psi of boost

1990 mx6lx , f2, nitrous,...13.5@102.9 on 87shot
1989 white pgt.. going for 600whp..1600cc inj
1990 probe gt 491whp at 29psi, holset hx35
1988 mx6gt 501whp @27psi..6262. now megasquirt
1990 mx6lx 348whp@ 18psi slipping clutch...sold

Last edited by ademan; 7-13-16 at 8:31.
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post #2 of 11 (permalink) Old 7-14-16, 9:55
 
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What about using the oil cap hole in the valve cover to vent, you could use a pressure release valve that opens at 10psi pressure or a solenoid valve and pressure switch that opens at a certain boost to release crank pressure.

Are you still running the air flow meter? because the vacuum of the intake pipe before the turbo can be used to suck some of that pressure out but if the AFM is before that point you'd be sucking in un metered air...

I would guess you are running you 4 hole PCV system independently/un-metered. So controlling oil from leaving the PCV system would be the only concern. You could put 4 small filters on your current holes and run a pump off the oil cap hole.





Are you using the factory turbo oil return on the block? you could run a hose and catch can off that and vent some of the crank pressure at the source.
With the amount of pressure your crank creates, oil must have a hard time draining back to the block under boost.

What symptoms does the crank pressure have? High idle after boosting? Dipstick pops out?

-------------------------------

Off topic, meth injection question.
I know the basic calculators and so on for water meth... but I am running it only above 16psi, I am thinking of running 100cc per PSI from there on.
So at 20psi I would be running 400cc's, any thoughts on what ratio I would want above that cc's to PSI (maybe 10-12whp per psi at that boost) but the factory intercooler I am running is corroding and too small and heat soaks above 16psi in hot weather, so the water meth is heat suppression until I get a bigger intercooler on the car.

http://www.cardomain.com/id/mazdacarnage
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post #3 of 11 (permalink) Old 7-14-16, 14:32 Thread Starter
 
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Quote:
Originally Posted by Mazda Carnage View Post
What about using the oil cap hole in the valve cover to vent, you could use a pressure release valve that opens at 10psi pressure or a solenoid valve and pressure switch that opens at a certain boost to release crank pressure.

Are you still running the air flow meter? because the vacuum of the intake pipe before the turbo can be used to suck some of that pressure out but if the AFM is before that point you'd be sucking in un metered air...

I would guess you are running you 4 hole PCV system independently/un-metered. So controlling oil from leaving the PCV system would be the only concern. You could put 4 small filters on your current holes and run a pump off the oil cap hole.





Are you using the factory turbo oil return on the block? you could run a hose and catch can off that and vent some of the crank pressure at the source.
With the amount of pressure your crank creates, oil must have a hard time draining back to the block under boost.



What symptoms does the crank pressure have? High idle after boosting? Dipstick pops out?

-------------------------------

Off topic, meth injection question.
I know the basic calculators and so on for water meth... but I am running it only above 16psi, I am thinking of running 100cc per PSI from there on.
So at 20psi I would be running 400cc's, any thoughts on what ratio I would want above that cc's to PSI (maybe 10-12whp per psi at that boost) but the factory intercooler I am running is corroding and too small and heat soaks above 16psi in hot weather, so the water meth is heat suppression until I get a bigger intercooler on the car.
Thats a great idea, I could vent the stock oil return to help relieve the pressure, and what is that oil cap vent call. i need that
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post #4 of 11 (permalink) Old 7-14-16, 14:42 Thread Starter
 
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Quote:
Originally Posted by Mazda Carnage View Post
Off topic, meth injection question.
I know the basic calculators and so on for water meth... but I am running it only above 16psi, I am thinking of running 100cc per PSI from there on.
So at 20psi I would be running 400cc's, any thoughts on what ratio I would want above that cc's to PSI (maybe 10-12whp per psi at that boost) but the factory intercooler I am running is corroding and too small and heat soaks above 16psi in hot weather, so the water meth is heat suppression until I get a bigger intercooler on the car.
Don't run it through the intercooler, go 6-12" before the throttle body. its is more efficient at that . Im running 100% alcohol, and using 2000cc jets, 2 m10 jet. thats a lot of meth. mine is setup to come on at 24psi to 32psi. on high boost. since my high boost is set at 30psi but it spike to 32psi. for your setup, will install 1 500cc or 800cc jet, dont waste your time with water, just 100% pre throttle

1990 mx6lx , f2, nitrous,...13.5@102.9 on 87shot
1989 white pgt.. going for 600whp..1600cc inj
1990 probe gt 491whp at 29psi, holset hx35
1988 mx6gt 501whp @27psi..6262. now megasquirt
1990 mx6lx 348whp@ 18psi slipping clutch...sold
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post #5 of 11 (permalink) Old 7-14-16, 15:39
 
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I googled "Baffled oil cap vent" and looked at the pictures.

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post #6 of 11 (permalink) Old 7-14-16, 18:25 Thread Starter
 
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Originally Posted by Mazda Carnage View Post
I googled "Baffled oil cap vent" and looked at the pictures.
I search through ebay and amazon and cant find it
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post #7 of 11 (permalink) Old 7-15-16, 17:35
 
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-12AN Banjo Valve Cover Oil Cap - Breather Adapter

VMS Racing Aluminum Vacuum Scavenger Engine Oil Cap Gun Metal for Honda Acura | eBay

Put the Ebay one in your cart, then go to my ebay and choose to view similar items and see what comes up.

You could just drill and thread a factory oil cap.

http://www.cardomain.com/id/mazdacarnage
BUILD IT, BEAT IT, BREAK IT, REBUILD IT, BEAT IT MORE, BREAK IT AGAIN, BUILD IT BETTER, BEAT IT THE MOST AND ?
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post #8 of 11 (permalink) Old 7-16-16, 2:49 Thread Starter
 
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Quote:
Originally Posted by Mazda Carnage View Post
-12AN Banjo Valve Cover Oil Cap - Breather Adapter

VMS Racing Aluminum Vacuum Scavenger Engine Oil Cap Gun Metal for Honda Acura | eBay

Put the Ebay one in your cart, then go to my ebay and choose to view similar items and see what comes up.

You could just drill and thread a factory oil cap.
I decided to vent the factory oil retyurn on the block and install the moroso vaccum extractor on exhaust to pull the pressure out, This will be adequate for whatever boost i threw at it.
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post #9 of 11 (permalink) Old 7-16-16, 2:50 Thread Starter
 
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Quote:
Originally Posted by Mazda Carnage View Post
-12AN Banjo Valve Cover Oil Cap - Breather Adapter

VMS Racing Aluminum Vacuum Scavenger Engine Oil Cap Gun Metal for Honda Acura | eBay

Put the Ebay one in your cart, then go to my ebay and choose to view similar items and see what comes up.

You could just drill and thread a factory oil cap.
Decided to vent the factory oil return on the block and install the moroso vaccum extractor on exhaust to pull the pressure out, This will be adequate for whatever boost i threw at it.

1990 mx6lx , f2, nitrous,...13.5@102.9 on 87shot
1989 white pgt.. going for 600whp..1600cc inj
1990 probe gt 491whp at 29psi, holset hx35
1988 mx6gt 501whp @27psi..6262. now megasquirt
1990 mx6lx 348whp@ 18psi slipping clutch...sold
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post #10 of 11 (permalink) Old 8-3-16, 6:46
 
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What were the symptoms of excess crankcase pressure? Was it blowing oil past the front crank seal?

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post #11 of 11 (permalink) Old 2-9-17, 15:15 Thread Starter
 
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Originally Posted by SinCity View Post
What were the symptoms of excess crankcase pressure? Was it blowing oil past the front crank seal?
No, excess vapor out the valve cover when i'm on high boost. I figure out the stock ring doesnt have enough gap to vent those gases, plus the stock piston is struggling at that hp range anyway. eventually hurt the number 2 ring on stock piston and swap them now to forge pistons
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