gti6 crank case vacuum?

[jimmyhackers]

my gti6 vents fron the crankcase, to the rocker cover, then from the rocker cover into the air intake... rocker cover has two tubes, crank gas in and a rocker gas out)

not sure how much of a vacuum this provided to the crankcase...

and since the rocker cover vent was slowly pissing oil into my intake i replaced it with a small catchcan/oil seperator vented to atmosphere.

getting rid of any potential vacuum on my crankcase.

recently i found crank case vacuum can increase HP.....

so my question is, how much might i of lost by doing the above?

[Gassmi]

You won't notice the power loss on the road. It's tiny, maybe 1-2hp at the very most.
The main downside is the smell of oily fumes now venting to atmosphere and a slightly messier engine bay.
If you're worried about it, plumb the catch can outlet back into the intake pipe before the throttle body. That'll restore the vacuum.

[E-bmw]

Gassmi said:

If you're worried about it, plumb the catch can outlet back into the intake pipe before the throttle body. That'll restore the vacuum.

Isn't that usually the way to fit them anyway?

It certainly is the way I have installed them before.

[jimmyhackers]

thanks for replies,

i went and did testing with a vacuum/boost guage in the time it took people to reply.

findings were....

1. rocker cover generates little to no pressure
2. crankcase makes under/about 1psi for all of 30-60 seconds on warmup (blowby i guess), then very little under opperation (increasing with revs) all sub 0.5psi
3. with a catchcan plumbed in and under vaccum from inlet manifold... i get about 17inhg of vacuum at idle and about 25inhg at high revs..
4. catchcan catches mostly water, little to no oil.
5. butt dyno has noticed no change (as expected)

i did google that a vacuum of 20inhg reduces waters boiling point down from 100C to 71C and 43c at 25inhg, so any moisture that forms inside the engine and is trapped by the oil will be more likely to evacuate now.