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I am pretty sure that the top lines on the 993 tank are the same as the 964. The set Up that I have holds vacuum. I installed a vacuum gauge in the system to confirm that I have vacuum pressure to operate the VRAM. At a little above I dle I pull 25lbs pressure and it will stay there even after I shut engine off. Usually will hold pressure for a couple of days, so must have a small leak some place, not enough to worry about.
Not that familiar with non-V 993 intake so hope this helps.
I am pretty sure that the top lines on the 993 tank are the same as the 964. The set Up that I have holds vacuum. I installed a vacuum gauge in the system to confirm that I have vacuum pressure to operate the VRAM. At a little above I dle I pull 25lbs pressure and it will stay there even after I shut engine off. Usually will hold pressure for a couple of days, so must have a small leak some place, not enough to worry about.
Not that familiar with non-V 993 intake so hope this helps.
Thanks Gus. Maybe your open air catch can has an one way valve which only allows air to escape from the can but not allows to draw any outside air in. Therefore, vacuum holds.
Also, may I ask how did you manage to put 2 oil catch cans in the engine room? I am still searching space to put 1 can. Your Varioam is even more diffcult I guess.
Actually, I would like to block off both of the pre/post bfly lines from the intake. And vent the oil tank to the atmosphere but you had mentioned that the oil tank needs vacuum, may I ask why?
My car is totally street use but I always can find oil in the intake manifold so I just want to eliminate any oil going into the intake.
Cheers
Last edited by 95993Cabrio; 11-14-2017 at 12:00 PM.
@jason when you say set you oil level for some movement, does that mean the oil level indicator on the dash will move a mm past the lowest level point. approx and this minimize the oil getting into the intake?
Just set your oil level so that there is the slightest of movement on the gauge and forget about it. Why complicate the situation?
Hi JA .. are you saying that oil level at 50% of guage is the problem and if one runs the guage 1mm above 0% (still in the red) the intake stays clean?
Remembering of course that there is only the last 1.25L shown by that guage.
Hi Gus, I have a question regarding to your config. I am not sure in 964 but in my 993 non Varioam, will your configure cause a vacuum leak?
What I mean is that the Tank vacuum line (after bfly) will loss its vacuum from your open air oil catch can via the oil tank.
Cheers
@Gus@JasonAndreas@95993Cabrio .. bumping this as I'm installing ITBs and the issue has re-arisen. What puzzles me is exactly what @95993Cabrio mentions here above - how do you have vacuum with a vented catch tank (open to atmos) which is connected to the oil tank - hence the oil tank is venter to atmos, no? So the vac pipe from tank to intake is thus vented too.
It must be there is a 1 way valve in the nec of the pipe you are venting to the unsealed catch can, correct? Maybe what we thought were restrictors (the 6mm and 1.5mm ones in the yellow and blue pipes in your orig post are actually one way valves - I am going to try blow into them and find out - ie my wheels ok, my pipes all be repositioned and the engine bay clean up continues
here some pics and a quick vid - still need to dyno this week hopefully once pipes all sorted. Concerned the vac pipe to oil tank from the throttle body is very underserviced as the ITB so much small than the plenum.
Last edited by HiWind; 06-30-2020 at 01:35 PM.
Reason: using the new @ function to tag - fancy!
@Gus@JasonAndreas@95993Cabrio .. bumping this as I'm installing ITBs and the issue has re-arisen. What puzzles me is exactly what @95993Cabrio mentions here above - how do you have vacuum with a vented catch tank (open to atmos) which is connected to the oil tank - hence the oil tank is venter to atmos, no? So the vac pipe from tank to intake is thus vented too.
It must be there is a 1 way valve in the nec of the pipe you are venting to the unsealed catch can, correct? Maybe what we thought were restrictors (the 6mm and 1.5mm ones in the yellow and blue pipes in your orig post are actually one way valves - I am going to try blow into them and find out - ie my wheels ok, my pipes all be repositioned and the engine bay clean up continues
here some pics and a quick vid - still need to dyno this week hopefully once pipes all sorted. Concerned the vac pipe to oil tank from the throttle body is very underserviced as the ITB so much small than the plenum.
An idling engine is constantly leaking vacuum, the reason it idles. You just can’t leak too much or you accelerate the engine 😊.
That’s the reason for the pin size hole in the pipe fitting on the oil tank. Once press builds in the tank from blow by, it will go in the direction of the least resistant, which should be the larger hole pipe fitting where your vented catch can is. (Reversing the direction of flow from when there is vac)
I use one way valves - the left side hoses coming off the intake that go to the brake booster etc. are totally different from the right side hoses that go to the oil tank. The left side provides the vacuum to operate the flaps in the intake manifold and build vacuum pressure in the vacuum canister by the air filter on a stock 964.
The hoses that go to the oil tank vent the main engine case and have nothing to do with the operational functions of the brakes or intake manifold flaps.
I do have a large one way valve on the primary crankcase vent line off the rear top of engine. This has no bearing on vacuum function but provides a negative internal pressure allowing free movement of internal parts with less air restriction.
An idling engine is constantly leaking vacuum, the reason it idles. You just can’t leak too much or you accelerate the engine 😊.
That’s the reason for the pin size hole in the pipe fitting on the oil tank. Once press builds in the tank from blow by, it will go in the direction of the least resistant, which should be the larger hole pipe fitting where your vented catch can is. (Reversing the direction of flow from when there is vac)
I use one way valves - the left side hoses coming off the intake that go to the brake booster etc. are totally different from the right side hoses that go to the oil tank. The left side provides the vacuum to operate the flaps in the intake manifold and build vacuum pressure in the vacuum canister by the air filter on a stock 964.
The hoses that go to the oil tank vent the main engine case and have nothing to do with the operational functions of the brakes or intake manifold flaps.
I do have a large one way valve on the primary crankcase vent line off the rear top of engine. This has no bearing on vacuum function but provides a negative internal pressure allowing free movement of internal parts with less air restriction.
@Gus Thanks man - you're experience is invaluable as usual.
1. before your thermostat has opened, if you start car and it starts to warm up, have you cracked your oil filler lid and seen a bit of oil in the neck or a few drops coming out as the neck cracks (yes @JasonAndreas my oil is just over red on the filler guage at temp at idle on flat surface )
2. regarding the ONE WAY VALVES - like used on GT3 RSR crankcase breather link; @JasonAndreas posted there too actually) - what is the PSI it opens at? What is the typical range of pressure out of the crankcase assuming no massive blow-by issues etc...??
3. yes agreed re your last statement but essentially if the brake or MAP or other user of vacuum from the plenum/ITB is linked to the small vacuum linked to oil tank - they all one system - unless one ways used on those or on the tank
Apologies if I was oversimplifying it, wasn't trying to be rude. The hole is so small at the tank, it's only vac'ing off oil vapor at idle. If you remove the vac, the vapor would build and come out where it can. I think, if you were going to remove the vac, you should remove the restrictor from the 1" ID breather hose at the tank so there's less restriction. The 964 setup works very similar to a pcv valve, there's slight vac on the tank at idle and then it opens up to vent off idle. The 964 just does this based on the restrictors on the two lines.
I do have a large one way valve on the primary crankcase vent line off the rear top of engine. This has no bearing on vacuum function but provides a negative internal pressure allowing free movement of internal parts with less air restriction
I'm not sure I understand the check valve at the crank case vent. The only times I ever see this is for forced induction, which makes sense. All the articles I've seen, show that more vac/venting the crank is good. What is the crack pressure on your check? Any insight on the rationale, is much appreciated.
HiWind -
1. No. At start up oil level is cold/lowest- so if high at this point oil level may be to high.
2. Sorry, can’t answer in specific numbers as did not measure other than use my mouth to insure valve functioned properly allowing pressure release going out / but no air back in.
3. I don’t link hoses/lines that provide feed to vacuum canister or feed lines to elements that use vacuum pressure to operate. All my crankcase Breather lines go to oil tank. I have removed all intake manifold lines going to oil tank now.
Ubipa- The creation of negative internal crankcase pressure is a HP benefit. When pressure in the crankcasecan be reduced, taken to zero or even made less than zero (vacuum), good things happen. Reduced crankcase pressureimproves the sealing of the rings in the cylinder. Increased differential pressure on the piston rings results in improved ring seal. Reduces internal windage - all HP increasers
This " line that connects to the intake manifold (after butterflies)." does not seem to be documented on Porsche diagrams. I have a 964 engine in a 72 chassis. I am guessing that there is not a spot for this vacuum line in the 72 tank, but it would be helpful. Short of switching to a 964 tank, any suggestions for making sure the needed vacuum is provided to the tank? Currently I only have the main breather line and the line that is open to atmosphere into the plenum / air cleaner. Any advice would be much appreciated as I don't want to cause oiling issues with this mismatch.
Originally Posted by Gus
HiWind - Yes, I now use 2 catch cans - so to say. I left the main line from the engine to the oil tank as it was/is. I added a sealed tank to the line that connects to the intake manifold (after butterflies). This is the line that creates a minor vacuum pressure in the tank. The tank I used is sealed to keep the vacuum pressure, but it allows any oil pulled through the oil tank to be captured in the catch tans and allows the air flow to continue on.
The third line that went to the intake prior to butterflies I ran to a standard catch can that is vented to the out side air.
I tried several configurations, found that the vacuum line from tank to engine is critical. But, this was were the oil was be pulled into the manifold. To control oil added the sealed separator tank. The other vent line also added some oil to intake at higher RPM. So vented it to catch can/air.
Closing off the vacuum line resulted in the oil tank becoming pressurized and pushing oil out of tank - not good.
11-14-2017, 09:39 AM
