Adam86

iTrader: (10)

Was reading a thread a while ago where someone mentioned running a line from their catch can to their exhaust on a PCV-less system. This way the vacuum from the exhaust essentially does the job of the PCV system (pulling crap from the crankcase) without throwing it into your intake. Is anyone running a system like this? Would love to see some pics to get an idea of a setup.
I was thinking I would run a -10 stainless line from the can to the turbo downpipe. I would also run a check valve in the line to keep from boosting my crankcase when I let off the throttle since I will still have a catback. Something like this, perhaps? Pretty simple...



Seems to make perfect sense. All of the good points of having a PCV system without the oily mess it makes in your intake and combustion chambers.

stangtrader

iTrader: (2)

I have thought about something similar for NA. But never thought about it on a Turbo car. It is just a crank case evacuation set up in short,but it may not work as good on a down pipe due the Exhaust pulses being chopped up.but that's just my theory. You can buy a kit from summit for cheap.its really a old technology but works decent

SirNemesis

I've considered it but I'm still to find any decent information on how well it'll work with relatively restrictive exhausts. I still run a couple of mufflers with my system to keep it stealthy and I'm worried that exhaust backpressure will be too high for this to work effectively when it matters.

kmracer

iTrader: (1)

check out "Crankcase Evacuation System" on summit. theres several options, but i plan on running 2 -8 or -10 lines from each valve cover directly to each check valve. its alot like your idea, but completely eliminates the need for the catch can and clutter.

Grr

iTrader: (2)

works great, pulls a strong vaccuum on your finger all the time. Make sure its on the front half of the valvecovers otherwise at the end of a long pull it likes to fill the muffler with oil.

Adam86

iTrader: (10)

Thanks a lot guys! Think I'll end up going this route. One more question though... Once I route it to the exhaust should I take the filter off of the catch can and take the breather off of the oil cap? Seems like this should be a sealed system or the vacuum from the exhaust would mostly just be pulling from the atmosphere instead of the motor.

bettonracing

iTrader: (3)

A sealed system** would shitcan Your seals (& potentially collapse Your hoses) - depending on Your ring gaps. The evac system needs airflow, just don't make it easy for the air to get in.

We ran a nitrous BBC with the exhaust evac setup using two 3" filter breathers. We saw the same crankcase vacuum (~6"Hg under load @ 7krpm)with the breather on & off - indicating that there were some potential gains by reducing the breather size. We were aiming for 8" to 10" Hg crankcase vacuum. Unfortunately we swapped to a dry sump before we could experiment with orifice (breather) sizes.

You may consider some or all of the following:

1. Use the smallest breather size You can find (usually 2" diameter). All else equal, the smallest breather will give You the lowest crankcase pressure. In reality it may give You 1"Hg less than the 3" ones, so nothing to write home about.
   
2. Use an oil separator (catch can) in the EVAC system. Reduces the amount of oil that gets into the exhaust.
   
3. Put a drain plug in the bottom of the muffler to drain any oil accumulation. I have no conclusive evidence but I've always felt uncomfortable about mixing oil puddles & ***** of fire in the car. We sprayed our mufflers with brake fluid every few races because most of that oil had coked up and didn't drain as readily.
   
4. Point Your exhaust as far away from the track as possible. Nobody - especially the guy running after You - will want to find out You left a nice shiny coat of oil on the top end of the track, particularly the braking zone. It'll take him weeks to get his seat cushion out of his clenched ***.

#2 may save You from doing #3 & #4.

Regards,

Kurt

** Keep in mind that once You have ring gaps (stock or opened) the system will never be fully sealed. That said if You try to fully seal it You'll likely run into the problems mentioned above.

Adam86

iTrader: (10)

Great points. Thanks for the tips! Hopefully the catch can catches most if not all of the crap coming into it. It's a cheapo ebay one but I stuffed it with scratch padding.

Build-it-Break-it

iTrader: (9)

Could you run a line from the catch can back to the oil pan so you wouldn't have to manuel drain it it? Its just oil and your oil filter would filter it right? That's what I planed on doing.

CarsandWomen

iTrader: (19)

or you could just use a catch can with baffles and check valves so you can use the vacuum from the intake, and not worry about any of this. one of the sponsors posted a thread about it a while back and they sell said catch can

Adam86

iTrader: (10)

I've looked into it but some of that crap would still be going into the intake and combustion chamber. There's just too many downsides to the PCV system even with a good catch can. I would rather have whatever doesn't get picked up by the catch can go into the exhaust. All of the pluses of crankcase evacuation and pressure relief without the bad of going through the intake.

kmracer

iTrader: (1)

thanks for the info betton, i was basing my plans off what parish had done with his street setup. its nice to see real #'s.

rotary1307cc

iTrader: (5)

i have the moroso kit on mine

just one breather on one cover going down and splitting into both of the scavenging tips in the exhaust

no can inline, but it couldn't hurt

drive it all over, and run the time in the sig, no problems, and my motor is on the loose side

back of the drivers bank

Adam86

iTrader: (10)

That's pretty slick! Where did you get those check valves?

CarsandWomen

iTrader: (19)

they look like the check valves from the AIR system of an Fbody

rotary1307cc

iTrader: (5)

They all come in the 50$ish moroso kit

I like it because I am absolutely not getting **** back into the intake and it is simple and not a hose monster under the hood

98Z28CobraKiller

iTrader: (17)

It shouldn't be mostly oil. If it is, you either don't have the system properly baffled or there is something wrong with your motor. It should come out <20% oil and the rest water (which you wont want back in your oil pan).

MIGHTYMOUSE

iTrader: (59)

what are the problems associated with a pcv system because i don't have any

'system' that sucks oil out of their engine and sprays it down on the track in front of the next guy.. well i dont like it one bit.

Fbodyjunkie06

iTrader: (10)

I'm with you on that one Dave. I know you have had your share of scares with fluid out the back door at the track.

I know you pretty much figured out how to make the PCV system work under boost on your own through trial and error.

ddnspider

iTrader: (26)

I did quite a bit of research on this awhile back. The issue with using the exhaust scavenge method is back pressure in the exhaust especially while in boost. After doing a lot of digging I followed a thread I found and did the same scavenge setup as people put in the exhaust, except I did it in my waste gate tube. During normal driving the crankcase is vented by my breather in the valve cover. Then, when the car gets into boost and the waste gate opens, it scavenges gases from the 2 valve covers.