Vacuum? In the crankcase? Are you sure?
For other engines maybe, but an inline 4-cylinder?

 

Yes, on hard engine braking deceleration with a closed throttle, especially if the pcv valve is still fitted.

 

But I thought your system is venting outside to atmosphere?!?
If the catch system is connected to the manifold, than you have vacuum on both sides - not just from the crankcase.

 

I always wonderred if it is ok to connect the PCV to the catchcan and then vent it and block the hole in the intake manifold?

Currently I have a breather filter on the front of the crank case and a catchcan between the PCV and the intake manifold.. at Roebling Road track the car will fill the catchcan in a session

It will send oil thru the PCV untill its well bellow the X's on the dipstick

Sometimes oil comes out the front as well thru the breather filter I think when the catchcan is full

 

BTW Peterson will change the size, type, and location of the 3 fittings on the breather tank I posted above for free

-Rob

 

Dan, I was also loosing about a quart to a quart and a half every 20mins on track. It was a big problem! Oil pressures were dipping into the 30s during extended high G turns towards the end of a 20min session and I was wasting about $30 in oil each day at the track just to replace what had been blown out.

Personally, I believe that the problem we are experiencing is different than that of the boosted guys. I think that in extended high G turns, the oil walks up the valve cover and gets into the baffling and is more or less forced out through the breather and or PCV during "normal" crank case pressures.

I think if you add additional venting, then the crank case pressure will find the path of least resistance and stop blowing out the oil through the breather and pcv, allowing the OEM baffle to do it's job as intended. Adding drain back to the oil pan will only improve the situation as I'm pretty sure that there will still be a considerable amount of accumulation.

As far as the oil drain back, the oil will find it's own level. Of course there will always be a tiny bit of oil in the line so the amount of oil it take to fill the pan will slightly increase as the oil in the line and pan will find it's own level, but gravity will allow it to flow back into the pan sooner or later (as long as the return is below the oil level in the pan and the catch can is mounted fairly high). I would imagine that it would easily flow back once on a straight and cornering Gs are no longer playing into the scenario. That would eliminate running a quart low, losing oil pressure, and wasting money on oil. This set up will be rather cheap. The modified tank is about $85 buck vs the super expensive ones you see in the market place.

-Rob

 

If you put a one way valve on the breather so the fumes can go out but not back into the motor you will find the crankcase develops vacuum under a hard overrun condition.

For track use I would suggest removing the pcv to stop oil getting into the inlet manifold. vent both the PCV and normal vent fittings into a catch can, vent the catch can to atmosphere and drain the catch can back to the sump as low as possible under the lower level. The catch can has to be large enough to temporarily hold oil that is carried out by fumes, and also large enough so the velocity inside the tank is slow enough for oil to condense out of the fumes. I normally use a 100mm diameter x 200mm tall canister.

My comment about crankcase vacuum is that this can potentially help draw oil back down into the sump when the vacuum condition exists.

Rob.ok's description about the drain back is spot on.

If the oil drains down the -10 line back to the sump its going to accumulate in the hose a fraction above the oil level, then the oil level between the sump and hose will equalise. On really heavy cornering the oil is going to try and find its way up the drain pipe. This is why its important to mount the catch can high up in the engine bay and as close to vertically above the fitting where it drains back into the sump.

 

More on this crankcase vaccum. I notice this on a race engine where crankvents from the rocker cover were just stuffed into a plastic canister so they reached to the bottom of the bottle. The engine never had anything but a oil film in the canister.

I then rearranged the system so the hoses ended just below the top of the plastic bottle. Guess what, the oil started to fill the bottle to the bottom of the hoses (and splash out all over the engine bay).

What was originally happening was the crankcase vacuum on the over run was sucking oil back into the motor. It could reach the oil in the container as the hoses were positioned on the bottom of the container.

Moving the hose ends higher in the container mean that the oil would build up in the container.

 

If you want to consider us Rob I can build you something 100% customizable at a competitive price. Moddiction and I are setting up a custom ordering option as we speak.

 

I think I'm gonna stick with the Peterson unit. Thanks for the offer though.