Why is it recommended that you !PCV when going FI?
Why is it recommended that you !PCV when going FI? Just curious as to why when you go forced induction it is recommended that you get rid of your PCV and go with a breather instead?
My pcv system was not able to evac my crank case pressure fast enough and I pushed the seal out of the timing cover on the dyno @ 5,000rpm... Oil every where. So I have bothe rocker covers going to a vented catch can and the pcv is gone. There are some down sides not having a vac source pulling crankcase gases out. When I can afford it I will get a belt driven vacume pump to clear the crank case.
Higher cylinder pressures with a boosted/nitrous engine will increase the amount of blowby past the rings, thus increasing crankcase pressure.
This will cost you horsepower and contribute to oil leaks.
Many builds get by with breathers, but the higher HP boosted setups could benefit from a quality belt driven crankcase vacuum pump.
A side benefit is increased piston ring life and better ring seal due to reduced ring flutter.
The only downside is the cost, and being able to fit one on your engine.
GZ Motorsports makes a kit, but the Star Racing and Moroso big boy pumps will require a custom gilmer drive and bracket setup.
This will cost you horsepower and contribute to oil leaks.
Many builds get by with breathers, but the higher HP boosted setups could benefit from a quality belt driven crankcase vacuum pump.
A side benefit is increased piston ring life and better ring seal due to reduced ring flutter.
The only downside is the cost, and being able to fit one on your engine.
GZ Motorsports makes a kit, but the Star Racing and Moroso big boy pumps will require a custom gilmer drive and bracket setup.
My uncle used the tubes on his n/a 434, crankcase evac. I'm not sure how they would work on a FI application though. I'd imagine it would still work and advance sells everything for that setup, you just need to weld the bungs in the exhaust.
My pcv system was not able to evac my crank case pressure fast enough and I pushed the seal out of the timing cover on the dyno @ 5,000rpm... Oil every where. So I have bothe rocker covers going to a vented catch can and the pcv is gone. There are some down sides not having a vac source pulling crankcase gases out. When I can afford it I will get a belt driven vacume pump to clear the crank case.
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The stock PCV system can not handle the extra pressure created by blow through of a FI application. Breathers help a little but the best solution is to add pan vacs. I have added two to my motor and they work quite well 
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formerly turbo4.8 (2014-06-25)
iTrader: (10)
Joined: Oct 2008
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From: FT Bragg, NC
just to a catch can setup.... if ur making over 1000 hrsp then use a vacuum pump. too much pressure in the cylinders is not good for any motor and you will have problems
So theoretically, if you removed your cats and still had the bungs in place for the rear 02's could one just run a line from each valve cover and then tie it into the rear bung on the exhaust stream? Would that pull a vacuum on the crankcase enough to effectively evac crankcase pressures/contaminants?
Depending on what FI setup you're referring too..
Most Centrifugal / TS Blowers
- I have seen the best results with this setup (up to 25psi on a TS/ 20psi on a centri) Running proper fittings and a good pushlock/LOLA hose from both valvecovers. Proper ventilation from both sides is critical.
Turbo Cars
- This kit has proven to be very effective on many turbo cars running up to 30psi. As long as the check valve is used, proper fittings/lines, and mounting the nipple where the exhaust helps scavenge the crankcase pressure, you shouldnt have a problem. Obviously the valvecover fittings in this picture are not needed. Just run a simple 90DEG fitting off each valvecover to a "T" fitting, and down to the exhaust. Or each valvecover to each bank of the exhaust. You can purchase the nipples and check valves separately from the kit.
Hope this helps.
Most Centrifugal / TS Blowers
- I have seen the best results with this setup (up to 25psi on a TS/ 20psi on a centri) Running proper fittings and a good pushlock/LOLA hose from both valvecovers. Proper ventilation from both sides is critical.
Turbo Cars
- This kit has proven to be very effective on many turbo cars running up to 30psi. As long as the check valve is used, proper fittings/lines, and mounting the nipple where the exhaust helps scavenge the crankcase pressure, you shouldnt have a problem. Obviously the valvecover fittings in this picture are not needed. Just run a simple 90DEG fitting off each valvecover to a "T" fitting, and down to the exhaust. Or each valvecover to each bank of the exhaust. You can purchase the nipples and check valves separately from the kit.
Hope this helps.
So theoretically, if you removed your cats and still had the bungs in place for the rear 02's could one just run a line from each valve cover and then tie it into the rear bung on the exhaust stream? Would that pull a vacuum on the crankcase enough to effectively evac crankcase pressures/contaminants?
^^ that was what I was thinking. I am having major problems with my sts kit. It is blowing oil out of the oil cap. Whichis where the oil return is. I did a compression test and all the plugs looks ok. I think it is the leaky cheap cap they give you with the kit. I am going to put some fittings in the vc's and go to a vented catch can when I swap out the valve springs and rockers.
i dont see why this couldnt work in n/a applications either. i had my tb off today and there is a bunch of oil in my 1k dollar intake because the breather line from the front of the valve cover pulls it in. the pcv line i have running to a catch can is dry as a bone. this is giving me an idea......
Teching In
Joined: Dec 2008
Posts: 15
Likes: 0
From: Flint, Michigan
Depending on what FI setup you're referring too..
Most Centrifugal / TS Blowers
- I have seen the best results with this setup (up to 25psi on a TS/ 20psi on a centri) Running proper fittings and a good pushlock/LOLA hose from both valvecovers. Proper ventilation from both sides is critical.
Turbo Cars
- This kit has proven to be very effective on many turbo cars running up to 30psi. As long as the check valve is used, proper fittings/lines, and mounting the nipple where the exhaust helps scavenge the crankcase pressure, you shouldnt have a problem. Obviously the valvecover fittings in this picture are not needed. Just run a simple 90DEG fitting off each valvecover to a "T" fitting, and down to the exhaust. Or each valvecover to each bank of the exhaust. You can purchase the nipples and check valves separately from the kit.
Hope this helps.
Most Centrifugal / TS Blowers
- I have seen the best results with this setup (up to 25psi on a TS/ 20psi on a centri) Running proper fittings and a good pushlock/LOLA hose from both valvecovers. Proper ventilation from both sides is critical.
Turbo Cars
- This kit has proven to be very effective on many turbo cars running up to 30psi. As long as the check valve is used, proper fittings/lines, and mounting the nipple where the exhaust helps scavenge the crankcase pressure, you shouldnt have a problem. Obviously the valvecover fittings in this picture are not needed. Just run a simple 90DEG fitting off each valvecover to a "T" fitting, and down to the exhaust. Or each valvecover to each bank of the exhaust. You can purchase the nipples and check valves separately from the kit.
Hope this helps.
Last edited by CBR-rider; Apr 13, 2009 at 12:20 AM.