Venting the valve cover works great, but there are caveats to doing this on a street car.
If you drive the car in the winter time with no pcv, but run some lines to a vented catch can, the lines will fill with condensation, then freeze. Sounds impossible, but it happens. Then the frozen lines are plugged with ice, and the next time you boost the car, the crankcase pressure blows out seals from all places. (Seen it happen plenty of times, and its always the same thing!)
On a street car driven in cold climates, I would recommend replacing the pcv with a good brass one (like from a turbo Supra) plumbed inline, to a catch can, and then to the intake plenum. Open up the second valve cover vent to run a larger line, to a second catch can, then to the intake tube.
The best idea is to run a Moroso vacuum pump. The only reason you don't see these on every high-boost setup, is because of the dork drag racing rules for sport front wheel drive that prohibits running a vacuum pump, because its supposed to be a street car class. The engine will make more power with the vacuum pump attached, because the combustion event isn't fighting against crankcase pressure to turn the crank.
Last edited by Specimen Kane : 09-22-2009 at 10:12 PM.
Reason: Imelda Marcos wanted to buy my shoes
All I can say is, try it. I have tried it on more than one version of 2.2 turbo, and even with a big open exhaust, it did not draw vacuum. Measured crankcase pressure went to zero, but no vacuum. A vent to atmosphere would have had the same effect.
All I can say is, try it. I have tried it on more than one version of 2.2 turbo, and even with a big open exhaust, it did not draw vacuum. Measured crankcase pressure went to zero, but no vacuum. A vent to atmosphere would have had the same effect.
I have been told the same thing but every thing I know tells me it should work especialy in a high velocity exhaust system
I can try and take pics of the valve cover tonight if I get off early enough to stop by my garage. I used stock locations so it's behind all the baffling still. A lot of ones I see people just pop a hole and a -12 in there. I don't think that size is needed and I would think it would be beneficial to retain the use of the stock baffling. Downpipe is simple with the nipple in just past my last o2 bung. I wanted to be able to use AN fittings everywhere so I just mig'd a steel fitting on the check valve similar to below.....
Car is still apart but should be running this weekend. We'll see how it works for sure. Previous spoke about Supra created enough vacuum at idle to feel it...I have felt it work on a turbo app just not the SRT-4 yet. I don't honestly see why it wouldn't work and work well...
couldnt we just use the pcv while in vacuum and the exhaust evac while in boost, or a mix of both. i dont think detonation from oil vapor contamination would be a problem even a little past 100kpa and once + manifold pressure is present the check valve would close.
you could use a catch can with a check valve on each leg for both sources
Not sure it would be detrimental to the ring seal, but it can be bad on all the oil seals. See Darrell's thread about this. I think he determined the 15" was the limit.
Not sure it would be detrimental to the ring seal, but it can be bad on all the oil seals. See Darrell's thread about this. I think he determined the 15" was the limit.
wow 15" would be allot i would assume without a mech pump you would never see that much. I always assumed as long as it saw some vacuum it was good (1-2")
once you get to a certain point I think he said he had to start turning seal around to keep them from sucking in... I'd like to see if running the system in the exhaust works, my dad wanted to try this on my car, but I dunno if it will work, I'm in for results
Sorry for the crappy pics, my camera sucks and the nice one is broke now thanks to my GF... Don't have $ for a new one now.
This is the first one I mocked up from a new spare one thanks to Ke (UAL_Kingpin). I may end up re-doing it, but I will know this weekend. The fittings are aluminum and just tigged on the cheap. No cleanup on anything yet etc. Welding on the cast VC tends to bring out all the black imperfections etc. The one on the PCV side is -10 and the other is -6. The side where the nipple was is a major PITA to get a fitting in and even worse to weld. I had to have the AN fitting's base lathed smaller to fit in the first ridge. The nipple does just pull out BTW for those wondering. I originally measured based on trying to tap and thread fittings in and it just wouldn't work. Would have cost way more to buy appropriate bits and taps and would have left very little metal in places. If you want to stay stock locations welding is your only option with this VC.
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i would assume without a mech pump you would never see that much. I always assumed as long as it saw some vacuum it was good (1-2")
Don't have $ for a new one now.
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