Catch cans and crank pressure
03-30-2015, 02:03 PM
#182
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No my car is not stock. 
My AOS line is vented. There's no extra lines on the turbo inlet pipe. I don't have any gauges on the crankcase, but that gives me an idea; I have a spare boost gauge, I wonder if I can just temporarily shove a hose down the dipstick tube and get an accurate measurement?
My AOS line is vented. There's no extra lines on the turbo inlet pipe. I don't have any gauges on the crankcase, but that gives me an idea; I have a spare boost gauge, I wonder if I can just temporarily shove a hose down the dipstick tube and get an accurate measurement?Both of those cam tower ports connect to the catch can? Judging by the filter on top of your CC I'm guessing it vents to atmosphere?? If that is the case I don't think you will have much crankcase vacuum at all. Any check valves used?
I connected a long hose from one of my cam ports to a vacuum gauge that was in the cab. I could easily view crankcase pressure/vacuum under driving conditions.
03-30-2015, 03:56 PM
#183
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Hey Dave,
Both of those cam tower ports connect to the catch can? Judging by the filter on top of your CC I'm guessing it vents to atmosphere?? If that is the case I don't think you will have much crankcase vacuum at all. Any check valves used?
I connected a long hose from one of my cam ports to a vacuum gauge that was in the cab. I could easily view crankcase pressure/vacuum under driving conditions.
Both of those cam tower ports connect to the catch can? Judging by the filter on top of your CC I'm guessing it vents to atmosphere?? If that is the case I don't think you will have much crankcase vacuum at all. Any check valves used?
I connected a long hose from one of my cam ports to a vacuum gauge that was in the cab. I could easily view crankcase pressure/vacuum under driving conditions.
03-31-2015, 06:41 AM
#184
03-31-2015, 09:54 AM
#185
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Thom.... AOS is plumbed back into the MAF pipe. Currently I'm using a setup similar to Marcoturbo's. (earlier post in this tread)
At idle I see about 80kpa (-3 psi). I use a port off the intake, with check valve, to create vacuum in the block.
At idle I see about 80kpa (-3 psi). I use a port off the intake, with check valve, to create vacuum in the block.
03-31-2015, 06:01 PM
#188
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Teddy,
Did you put any restrictor in the line you run from the intake ?
-3psi at idle looks a bit high. Even 3 In/hg (if the online unit convertissors work...) is quite high. With the stock J boot, the highest vacuum on a stock car is around 100mbar (3 In/hg) at WOT.
Out of curiosity, with your gauge, have you ever checked the crankcase pressure at WOT (and PT) ? I Wonder if the MAF tree really sucks air from the AOS when boosting.
Did you put any restrictor in the line you run from the intake ?
-3psi at idle looks a bit high. Even 3 In/hg (if the online unit convertissors work...) is quite high. With the stock J boot, the highest vacuum on a stock car is around 100mbar (3 In/hg) at WOT.
Out of curiosity, with your gauge, have you ever checked the crankcase pressure at WOT (and PT) ? I Wonder if the MAF tree really sucks air from the AOS when boosting.
03-31-2015, 06:33 PM
#189
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Did you put any restrictor in the line you run from the intake ?
Yes. I did this with the vacuum gauge connected. With no restriction there was zero vacuum present in the crankcase. I kept reducing the restricor size until the crankcase vacuum was around 80kPa.
Light cruising and WOT showed zero vacuum in crankcase.
Yes. I did this with the vacuum gauge connected. With no restriction there was zero vacuum present in the crankcase. I kept reducing the restricor size until the crankcase vacuum was around 80kPa.
Light cruising and WOT showed zero vacuum in crankcase.
04-01-2015, 04:10 AM
#190
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04-01-2015, 10:21 AM
#192
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I was getting pressure spikes (about 8psi) in the crankcase whenever the recirculating valve dumped back into the MAF. This happened because the connection to the recirculating valve was directly across from the catch can connection on the MAF. Whenever it dumped it shot the boost across the MAF, down through the catch can and into the block. The solution was to relocate the catch can port on the MAF tree. Zero spikes since moving that port.
Not sure how you can create vacuum in the crank at WOT when there is some blow by to contend with. Aren't most systems designed to remove the blow by instead of adding vacuum at WOT?
04-01-2015, 05:21 PM
#194
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Blow-by is always removed by vacuum. At WOT, the crankcase should also be under vacuum.
I think a 45degree connection for the AOS line to the MAF pipe (instead of the 90degree angle we have on our MAF trees) should help to get more succion flow from the turbo when it spins hard. A flap inside the MAF tree or a connection designed like an exhaust scavenging port could also work.
Though I didn't have time enough to explore further...
I think a 45degree connection for the AOS line to the MAF pipe (instead of the 90degree angle we have on our MAF trees) should help to get more succion flow from the turbo when it spins hard. A flap inside the MAF tree or a connection designed like an exhaust scavenging port could also work.
Though I didn't have time enough to explore further...
04-01-2015, 05:51 PM
#195
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I plan on getting my car out of hibernation very soon.
I could hook up my vacuum gauge to a port on the MAF to see if any vacuum is generated by the turbo at PT and WOT. With the MAF's cone filter less than a foot away I'm curious to see how much vacuum if any...
I could hook up my vacuum gauge to a port on the MAF to see if any vacuum is generated by the turbo at PT and WOT. With the MAF's cone filter less than a foot away I'm curious to see how much vacuum if any...