Replacing the cam cover breather
- Thread starter CHe
- Start date
The 1UZFE EGR Delete Kit is available for sale here.
With the double breather, the OEM PCV system gets dismantled, because, especially with a performance motor, we don't want raw oil vapor going into the combustion chambers as it promotes knock.
So as Rod said, the solution is to run the valve cover vents to an oil separator (catch can) and then the outlet of the separator goes to a point in the intake system before the turbo or supercharger that will only produce vacuum.
Some people will just vent the catch can, but you wind up with a smelly garage.
Note: If you're still running a MAF, you definitely shouldn't vent the catch can; its return line should be tied back into the intake AFTER the MAF.
seconded... but
If you can introduce some crankcase vacuum the engine will run better. If you vent the cam covers straight to atmosphere (thru a vented can) the best you can possibly hope for is 0psi crankcase pressure no matter what the throttle position.
If you vent the cam covers to a sealed can/separator with an outlet into the intake mani you might get a little bit of vaccum in the crankcase even at WOT, but will get a lot of vacuum at part throttle/cruise - probably more than the stock setup because of the larger plumbing (bigger is better) - plus you should have less oil vapor if you use the right type of can.
The difference between the 2 methods is actually enough to affect fuel consumption, will make sure you dont get stuck with the fumes, and can actually give a bit more power/throttle response. The can/separator is tricky to get right though. If you can utilise stainless wool between the inlets and outlet you'll trap more vapor.
Cool, thought that might be the case. I'll be getting into this today!
You can use the existing grommets and just jam -6 AN fittings in there. They're a pretty tight fit and the -6 size should be OK unless it's a blown (turbo or SC) motor, or you have LOTS of blowby.
Or you can tap the holes out and thread a fitting (IIRC a 3/8 NPT tap works OK). (Be sure to use plenty of grease when you're tapping to catch the swarf, then flush the cover out really well after)
For the latest set of covers for the #2 engine, I had the existing holes welded up on the top and sides and I put -8 AN nipples at the rear of the covers and had them welded in.
Here's a pic with the -6 AN's jammed in.
Or you can tap the holes out and thread a fitting (IIRC a 3/8 NPT tap works OK). (Be sure to use plenty of grease when you're tapping to catch the swarf, then flush the cover out really well after)
For the latest set of covers for the #2 engine, I had the existing holes welded up on the top and sides and I put -8 AN nipples at the rear of the covers and had them welded in.
Here's a pic with the -6 AN's jammed in.
Attachments
My engine runs two of the larger dog leg breathers from the 1UZ.
I drilled the hole inside of the dog leg out to the largeest I could. Most won't be aware there is a restricter inside it.
If you remove the grommet the beather from the other cam cover will be a push fit. I used some Loctite and it works well. This mod gives over 8 times the breathing ability of the stock set up.
I drilled the hole inside of the dog leg out to the largeest I could. Most won't be aware there is a restricter inside it.
If you remove the grommet the beather from the other cam cover will be a push fit. I used some Loctite and it works well. This mod gives over 8 times the breathing ability of the stock set up.
hungryforinfo
New Member
Got any pics of your work Zuffen?
Thermactor
Member
So what should someone with a forced induction motor do about their PCV setup?
With the double breather, the OEM PCV system gets dismantled, because, especially with a performance motor, we don't want raw oil vapor going into the combustion chambers as it promotes knock.
So as Rod said, the solution is to run the valve cover vents to an oil separator (catch can) and then the outlet of the separator goes to a point in the intake system before the turbo or supercharger that will only produce vacuum.
Some people will just vent the catch can, but you wind up with a smelly garage.
Note: If you're still running a MAF, you definitely shouldn't vent the catch can; its return line should be tied back into the intake AFTER the MAF.
clubagreenie
New Member
What difference does venting the catch can make in a MAF setup? None I'd say?
Justin
Justin
Justin, on the Supra side some guys with MAF's and piggybacks years ago reported the same rich running syndrome when they plumbed their catch cans in before the MAF, as when they did it with their BOV's. I know it doesn't sound logical, because with the BOV case, it is just intake air, however with the catch can, the fumes are a product of combustion.
Logical or not, I also believe this is the way Toyota plumbed the exhaust side cam cover vent, in the stock twinturbo setup. I'll have a look at my son's 2JZ-GTE this morning and confirm this. Perhaps Toyota did it this way just to avoid getting the MAF oiled up - which is the more probable reason!
Logical or not, I also believe this is the way Toyota plumbed the exhaust side cam cover vent, in the stock twinturbo setup. I'll have a look at my son's 2JZ-GTE this morning and confirm this. Perhaps Toyota did it this way just to avoid getting the MAF oiled up - which is the more probable reason!
clubagreenie
New Member
I dont see what that has to do with your comment re: "you definitely shouldn't vent the catch can"
It's blowby. Who cares (aside from the EPA) where it goes.
The problem with BOV's is they vent air from the intake that has already been metered and fuelled for. you vent it out of the inlet system you get a rich run. Thats a totally different scenario and I dont see the relevance.
It's blowby. Who cares (aside from the EPA) where it goes.
The problem with BOV's is they vent air from the intake that has already been metered and fuelled for. you vent it out of the inlet system you get a rich run. Thats a totally different scenario and I dont see the relevance.
Justin, right you are; that first post was a bit early in the morning and I hadn't had any coffee yet 
I agree, catch cans can be vented or replumbed at the owner's preference. If one is running a MAF, and chooses to replumb it, then it ought to be plumbed in after the MAF, as Toyota did it with the 2JZ.
I agree, catch cans can be vented or replumbed at the owner's preference. If one is running a MAF, and chooses to replumb it, then it ought to be plumbed in after the MAF, as Toyota did it with the 2JZ.
gmacrae
Member
seconded... but
If you can introduce some crankcase vacuum the engine will run better. If you vent the cam covers straight to atmosphere (thru a vented can) the best you can possibly hope for is 0psi crankcase pressure no matter what the throttle position.
If you vent the cam covers to a sealed can/separator with an outlet into the intake mani you might get a little bit of vaccum in the crankcase even at WOT, but will get a lot of vacuum at part throttle/cruise - probably more than the stock setup because of the larger plumbing (bigger is better) - plus you should have less oil vapor if you use the right type of can.
The difference between the 2 methods is actually enough to affect fuel consumption, will make sure you dont get stuck with the fumes, and can actually give a bit more power/throttle response. The can/separator is tricky to get right though. If you can utilise stainless wool between the inlets and outlet you'll trap more vapor.
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I have decided to move my cam cover outlets to the front out of the way of everything else happening back there but I have a few questions:
1. Do people remove the splash guard in the cam cover to do the alloy work?
2. If so, what's the best way to remove and reattached?
3. What size outlets should I use? With a 300+rwkw v8 engine revving to 7000rpm?? I was just advised to run -12AN size fitting.. they look HUGE! Is this about right?
1. Do people remove the splash guard in the cam cover to do the alloy work?
2. If so, what's the best way to remove and reattached?
3. What size outlets should I use? With a 300+rwkw v8 engine revving to 7000rpm?? I was just advised to run -12AN size fitting.. they look HUGE! Is this about right?
Red Supra
New Member
Take a look at a bone stock RB26DETT, they got super-sized breather tubes and hoses from the factory.
2JZ-GTE on the other hand uses much smaller breather tubes and hoses. The last thing you want is pressure in the crankcase and pressure in the combustion chamber fighting each other.
2JZ-GTE on the other hand uses much smaller breather tubes and hoses. The last thing you want is pressure in the crankcase and pressure in the combustion chamber fighting each other.
hungryforinfo
New Member
I looked at pulling the splash guard, but it was too much hard work and reattaching it was going to be difficult too. If you want to clean under there, use thinners, or degreaser and then metho. Seemed to work for me.
Cool, thought that might be the case. I'll be getting into this today!
