My catch can setup...
12-20-2006, 01:34 PM
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My catch can setup...
... figured I would post here in this section as FI guys might find some interest...
I installed my catch can and also went with the Krank Vent set up. Vette guys have said good things about the theory behind the Krank Vent setup so I thought I would give it a try... as I recently started pushing oil through my front main seal during prolonged WOT runs. I also noticed standing oil in my j-tube the couple of times I have had it off. Below are the pics. The second pic shows the smaller of the 2 Krank Vents in line with the PCV to the catch can. This one allows vacuum of the crank case but prevents boost. Well, I don't have to worry about boost prior to the supercharger but it should work there. The last picture has the larger one in line with the valve cover and the intake duct. The larger one prevents air from entering the crank case yet has an amazingly small cracking pressure in the event of positive crank case pressure.
General feedback from at least one of the vette guys is that part throttle response is improved. He did mention a suction noise coming off of an extended WOT run and thinks the intial vacuum spike might be introducing enough vaccum pressure to pull air through the front and/or rear main seals. Its possible so he has since put a bleeder valve on the valve cover to introduce a very small amount of freash air less than normal and he says its worked great. I am going to play with it as it sits and if I start to hear any sucking vacuum noise coming from the engine compartment I may hook up a vacuum gauge to the crank case and see whats going on...
We'll see how it works... just thought I would share...
Bill
I installed my catch can and also went with the Krank Vent set up. Vette guys have said good things about the theory behind the Krank Vent setup so I thought I would give it a try... as I recently started pushing oil through my front main seal during prolonged WOT runs. I also noticed standing oil in my j-tube the couple of times I have had it off. Below are the pics. The second pic shows the smaller of the 2 Krank Vents in line with the PCV to the catch can. This one allows vacuum of the crank case but prevents boost. Well, I don't have to worry about boost prior to the supercharger but it should work there. The last picture has the larger one in line with the valve cover and the intake duct. The larger one prevents air from entering the crank case yet has an amazingly small cracking pressure in the event of positive crank case pressure.
General feedback from at least one of the vette guys is that part throttle response is improved. He did mention a suction noise coming off of an extended WOT run and thinks the intial vacuum spike might be introducing enough vaccum pressure to pull air through the front and/or rear main seals. Its possible so he has since put a bleeder valve on the valve cover to introduce a very small amount of freash air less than normal and he says its worked great. I am going to play with it as it sits and if I start to hear any sucking vacuum noise coming from the engine compartment I may hook up a vacuum gauge to the crank case and see whats going on...
We'll see how it works... just thought I would share...
Bill
12-20-2006, 04:29 PM
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The catch can was $85... the Krank Vent (both) was $120. Very expensive vents but EXTREMELY effective. So much so I had to pull the one off my valve cover for now because I was pulling 22-24 inches of vacuum on decel (foot off pedal) during normal driving and started hearing this squealing noise... definitely pulling air through the rear main. There was so much vacuum in my crank case I struggled to pull my oil fill cap off while it was running... sounded like pulling the vacuum line off your brake booster (for those who have vacuum assisted). Gonna have to throttle incoming air into the crank case... but have a good means of allowing positive crank pressure venting. More work needed.
12-20-2006, 05:07 PM
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I don't understand the need for the one on the intake duct. That line is there to let fresh metered air in the crank case. If that one wasn't there you wouldn't be pulling a huge vacuum in the crankcase and pulling air pass the seals.
22-24 inches vacuum is normal on my truck on decel. 22 after letting off and it'll hit 24 when DFCO kicks in.
Nice looking stuff though.
22-24 inches vacuum is normal on my truck on decel. 22 after letting off and it'll hit 24 when DFCO kicks in.
Nice looking stuff though.
12-20-2006, 05:32 PM
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Bill my truck (6.0L) regularly pulls 22-24 inches on decel just as said above. You have a lot more connections now are you sure one of them is not leaking. Are those one-way valves? Make sure you have them installed the right way. I also agree with XLR8NSS that you don't need one on the passenger side since you are not creating boost before the TB.
12-20-2006, 06:53 PM
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Originally Posted by Mort
Bill my truck (6.0L) regularly pulls 22-24 inches on decel just as said above. You have a lot more connections now are you sure one of them is not leaking. Are those one-way valves? Make sure you have them installed the right way. I also agree with XLR8NSS that you don't need one on the passenger side since you are not creating boost before the TB.
I pulled the one off the passanger side Krank Vent off for now. With the engine running the valve cover nipple pulls a decent amount of vacuum... so its hooked back up to the bottom of the Radix intake tube as normal. I'm going to ask some more questions from the guys that have used these with success. I guess the point in trying to use these is that they are so effective that they can maintain a vacuum environment in the crank case, under boost conditions, longer than not using them. Once blow by starts to increase that is what the larger of the 2 Krank Vents is for, mounted on the passanger side... to crack and let any positive pressure out. But its closed under normal driving conditions and that is what is creating a totally sealed crank case... allowing the PCV side, with the other Krank Vent, to essentially put an incredible vacuum on the crank case. I guess I need to figure out what the right amount of "bleed" fresh air needs to go into the crank case under decel or idle conditions so that I'm not pulling air through my crank seals...
12-20-2006, 07:46 PM
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Here is my thinking on the matter.
If you take the passenger side valve out of the fresh air line you allow air into the crankcase during normal non boost conditions. Running a vacuum in the crankcase in these conditions would just cause extra wear on the rings/cylinder walls/seals right? With the valve out of the passenger side you also will still pull air out of the crankcase under boost conditions since the line is on the suction side of the blower and the PCV line is closed to boost. I assume it does this with the valve in also since it has a very low cracking pressure but, with the valve in you run the vacuum in the crankcase all the time which I'm not sure is very good.
If you're really only worried about boost conditions I don't see the need for the passenger side valve as the system should be doing the same thing under boost with or without it if I understand correctly.
If you take the passenger side valve out of the fresh air line you allow air into the crankcase during normal non boost conditions. Running a vacuum in the crankcase in these conditions would just cause extra wear on the rings/cylinder walls/seals right? With the valve out of the passenger side you also will still pull air out of the crankcase under boost conditions since the line is on the suction side of the blower and the PCV line is closed to boost. I assume it does this with the valve in also since it has a very low cracking pressure but, with the valve in you run the vacuum in the crankcase all the time which I'm not sure is very good.
If you're really only worried about boost conditions I don't see the need for the passenger side valve as the system should be doing the same thing under boost with or without it if I understand correctly.
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12-21-2006, 09:07 AM
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Nice explanation, makes a lot of sense. When the throttle plate is fully or partially closed and the intake manifold is under high vacuum the passenger side venting allows metered air into the crankcase so excessive vacuum is not created in the crankcase and helps purge any caustic gases and condensation that form.
If the Krank Vent is causing too long a delay maybe you are better off without it and it sounds like you will still be getting the benefit of some crankcase vacuum under boost.
If the Krank Vent is causing too long a delay maybe you are better off without it and it sounds like you will still be getting the benefit of some crankcase vacuum under boost.
12-21-2006, 10:03 AM
#10
I wonder how this system differs from just using a diffrent one way valve?
No matter what I have tried to date, I still get the oil fill cap pushing out of the passenger side valve cover under boost. Then again maybe I have a cracked piston ring land, still have not done a leak down test.
Either way it sounds like this sytem is working for you Bill Reid.
No matter what I have tried to date, I still get the oil fill cap pushing out of the passenger side valve cover under boost. Then again maybe I have a cracked piston ring land, still have not done a leak down test.
Either way it sounds like this sytem is working for you Bill Reid.