crank case pressure data

[caged]

Iv been getting a few logs on crank case pressure on 4g63s lately. This was a run of the mill forged 2L evo 7 on around 20ish psi for the green run, its on a factory breather and a gt pumps 712 and was just starting to push the dip stick. Pink is a dash 8 to atmosphere. Red is dash 8 to sealed catch can and back to the intake, its on about 26psi for those runs. As you can see it pulls to vacume which i thought was impressive.

We see alot of evos come through with big turbo loose built motors on 30+ psi and factory breather, with a big spring holding the dipstick down. The problem is even worse on evo 1-3 and vr4 as the have 4 less oil drains from the head and most of the reason the head fills with oil.

 

[4piknup]

How can the red one be in vacuum? Maybe if its referenced to boost?
A vacupan into the exhaust maybe can show vacuum at revs and boost, but nothing else.

Good job on logging this stuff. Its great info.

Is the red run. Is the dash8 go into intake pre turbo, and after filter like oem? And the pcv is still fitted?

If so, maybe you should measure intake for restriction before turbo. As that is the source for the neg pressure on crankcase??

 

[4piknup]

And i dont think vacupans work with mufflers on the street as there would be some pipe pressure. I think they work ok on open pipes.

could run them into a screamer pipe effectively maybe?

 

[caged]

How can the red one be in vacuum? Maybe if its referenced to boost?
A vacupan into the exhaust maybe can show vacuum at revs and boost, but nothing else.
Good job on logging this stuff. Its great info.
Is the red run. Is the dash8 go into intake pre turbo, and after filter like oem? And the pcv is still fitted?
If so, maybe you should measure intake for restriction before turbo. As that is the source for the neg pressure on crankcase??

lol my dyno pressure sensor does not lie, vacume=below atmospheric pressure. It only just dips in but its still seeing vacume. And your statement is wrong, think about how an exhaust scavenging breather system works and then think about what an intake is doing. Yes similar to oem but im not giving away everything, and yes it runs a pcv as its daily driven. Intake is not a restriction. It made no more power with the intake off and just a 4inch pipe slid over the turbo snout.

 

[4piknup]

Vacupans work on a venturi. So they can work. I dont think they good for street tho.

I dont know what you have done. Maybe made the intake a venturi to scavenge the crankcase.
whatever you have done- good effort.

 

[caged]

Bingo.

 

[brisvr4]

I set mine up years ago with a -12 from the valve cover into a sealed catch can then into the turbo intake with a modded fitting to help increase the venturi effect.
My dipstick stays put on a 275000 km old factory stock 6 bolt with a 62mm turbo at around 35psi of boost.
There's a lot of advantage to trying to create a vacuum in the crankcase under boost
Lately I've been toying with the idea of actually using an electric vac pump to help it along.

 

[4piknup]

Lots of advantages. Absolutely. As long as we not creating too big a pressure drop by doing so.

Sounds like you guys have it sorted

 

[bazeng]

I've been keeping an eye on a mech vacuum pump.

Any power difference?

 

[Benzo4gT]

I'd be willing to try one of these things about 3 ft down the dump pipe. I've read articles before and it does seem like an old school way to do it, but I see no reason why it wouldn't work with a free flowing exhaust.
http://vibrantperformance.com/catalog/product_info.php?cPath=1022_1069&products_id=1243

 

[khubner1]

where would i find a venturi style intake breather because my engine does seem to have a crank case pressure issue.

 

[evo-gsr]

I'd be willing to try one of these things about 3 ft down the dump pipe. I've read articles before and it does seem like an old school way to do it, but I see no reason why it wouldn't work with a free flowing exhaust.
http://vibrantperformance.com/catalog/product_info.php?cPath=1022_1069&products_id=1243

Nice find!!

 

[bazeng]

I've tried those vac u pan in the exhaust. Didn't work.

Probably be ok after the muffler. Back pressure in the exhaust caused the engine to not be able to breath and oil out the dip stick was the outcome

 

[evo-gsr]

Interesting ^

 

[4piknup]

I think it would work in a screamer pipe

 

[caged]

Depends on manifold back pressure and gate size as to if it would work on a screamer pipe at all. I have thought about trying to run a vac pump but to do it properly you need to run a mechanical pump imo. Next drysump car we tune ill log that too.

 

[4piknup]

Put it after the gate on the screamer. Maybe flare the pipe a little as it passes the takeoff point for more neg pressure

but its no good for a road car. So its all pie in sky really.

i think a mech pump also so it pumps harder as revs increase.

 

[evo-gsr]

Why is it no good for a road car?
Plenty of road cars have screamer and external gate.

 

[4piknup]

I spose its no more illegal than a screamer.
Its a open pcv system. They stopped them in 1972. Adr27a. same time as carbon canisters went on.

 

[Benzo4gT]

I have a vac pump on the back of one of my landcruiser diesel alternators.............I might put on my mad scientist coat and goggles and hack up a workable vac pump just for beans and boners, it might just work!