Gretch

See the air pump / crank case ventilation mod PorKen has a thread running on. What are the opinion's of the various boost experts here, on this mod?

Lagavulin

Z has the most experience playing around with it on his S4, and I think the jury is still out as he was having problems seperating out the oil. If I remember correctly, he was getting well over 5 psi of vacuum in the crankcase.

PorKen

Lag,

Did you mean 5 psi of pressure? Or 5 inches of mercury for vacuum?

Lagavulin

PorKen, whatever he was getting, it was negative pressure as he was using the stock S4 air pump to pull the vacuum. The gauge he was using was a standard engine manifold pressure one. Hopefully he'll see this thread and clear up the actual numbers.

John..

Gretch,

I am in the process of installing an aircraft air-oil separator in the Bastard. These engines are horrible for lifting oil through the breather, and it is 3X worse when on the steroids (boost). It is basically nothing more than a cannister with 6 layers of screen around an internal pipe to get the oil to collect and drain out the bottom. I will be hooking this up to my oil scavenging system to draw the oil back into the crankcase.

Key with any of this is you have to have the oil hot enough to drive out the water vapor....this is the part I am not totally comfortable with. Right now I have a catch can off of the breather hose on the car and I do get a good bit of oil into the can when I run into the manifold pressure a lot.

My separator will probably be installed within the next month or so, so I will let you guys know how it works out.

Gretch, we don't want you blasting out pollutants into the pristine NH atmosphere!

PorKen

I'm interested!

5 PSI = 10 inches mercury. (15 inches is oft said to be the safe max)

I didn't use the air pump directly, because I understood that the carbon seals inside the pump would turn to mush if there was oil intake.

Some vacuum pumps are basically emission air pumps with a different sealing surfaces. The caveat is that they must suck some oil through the pump in order to lubricate them.

If Lag is having no problems with his pump... hmmm...

Lizard928

how hot does the oil have to be to burn the water and crap out of it?

Lizard928

also what do the 951 guys have for venting pressure?

Lagavulin

Porken, Z is running the experiment on his car.

Gretch

Pictures John , pictures. BTW, not to worry. While I like some of PorKen's design (using the pump to creat vacume by blowing through a "T" tube), I want to put the oil back into the crank case. For my application, venting it to the rear tires is Russian Roulette.................

John..

http://www.homebuilt.org/vendors/pow...ero/price.html

Nice guy who makes these in IL. He told me the oil should be 180 degrees to drive the water vapor out, but I have no way of really knowing what to expect.

I do know I am tired of smelling the crap that breathes out of the catch can vent.

Lizard928

another question are there any boosted cars w/ a dry sump installed?

Zandramus

at sea level 212 degrees or its boiling point at other altitudes. you will see some water start to go to vapor below this point, but you now have a time factor involved to get all of the water out.

oil temps will run much higher than this coming off the bearing surfaces so this shouldnt be a problem.

also under vacuum water boils at a much lower temp, I suggest you do some looking on the internet for articles on vapor pressure.

Z

Gretch

Does this point to a design consideration in the oil catch can location. I.e. should it be located in a hot, (but not "hot-hot") location such that the water vapor does not condense on the screens, but continues on, to vent to the atmosphere.

How much of a real problem is this water vapor anyway? Don't some charge cooling systems use water mist?

My reason for wanting a catch can is to limit the octane reduction induced by oil ingestion, in my bosted shark. I am interested in a system that recycles the oil to the crankcase rather than ingests the mist into the intake manifold. So PorKen's solution looks good for the first half, I just need to design the catch can recirculation piece, a la John's suggestion.

tresamore

Hey Gretch,
If you need to check anything as far as clearances or trial fitting goes, my 87 is still apart, w/ the engine (long block now) on a stand. You mentioned somewhere that you commute to Boston. I'm at 93 ex. 1 if you need an "exploded view" of a 928 for your project.

Randy