Which is better location for catch can "dirty" line
Which is better location for catch can "dirty" line Using a Mighty Mouse "draft" catch can. Not going to have a fresh air source, just vacuum from manifold pulling pressure out of crank case via line from engine to CC, then line from CC to intake manifold. I'll be using -10 AN fittings and hose.
First question, crank case pressure is the same at valley cover and valve covers correct? I'd imagine it is since oil flows from top of heads to bottom of crank case. It's not air tight or anything.
Second, if the pressure and vapors are the same in both, would it be better to use the -10 AN oil cap fitting and pull from valve cover, or put a -10 AN fitting in the valley cover? Or does it matter? Maybe one is better at collecting vapors than the other?
First question, crank case pressure is the same at valley cover and valve covers correct? I'd imagine it is since oil flows from top of heads to bottom of crank case. It's not air tight or anything.
Second, if the pressure and vapors are the same in both, would it be better to use the -10 AN oil cap fitting and pull from valve cover, or put a -10 AN fitting in the valley cover? Or does it matter? Maybe one is better at collecting vapors than the other?
TECH Addict
Joined: Jul 2013
Posts: 2,189
Likes: 123
From: Portland, Oregon
I would use whatever location makes for the cleanest packaging, personally.
I definitely prefer function before form, but the difference between the two proposed locations will be negligible, if there are even measurable differences in the first place. The valve cover(s) may offer a slight advantage in crankcase vapor collection, due to their height above the valley cover, but (once again) the difference is probably negligible.
I definitely prefer function before form, but the difference between the two proposed locations will be negligible, if there are even measurable differences in the first place. The valve cover(s) may offer a slight advantage in crankcase vapor collection, due to their height above the valley cover, but (once again) the difference is probably negligible.
You still have a fresh air source. You have to have one. I have the RX can and have it routed like this:
Driver cover and LS6 valley cover Tee'd together and going into can dirty side. Can clean side into the manifold. The passenger cover is connected to either the air filter or the TB port depending on SD or not. With SD the clean air can be anywhere that isn't behind the TB blade. MAF needs to be between the TB blade and the MAF.
Many use the oil fill port as the fresh air source and pull the crap from the opposite valve cover.
Driver cover and LS6 valley cover Tee'd together and going into can dirty side. Can clean side into the manifold. The passenger cover is connected to either the air filter or the TB port depending on SD or not. With SD the clean air can be anywhere that isn't behind the TB blade. MAF needs to be between the TB blade and the MAF.
Many use the oil fill port as the fresh air source and pull the crap from the opposite valve cover.
Exidous thats exactly how I had mine routed. Even had a RX can too.
But the two problems were, with my built 408, higher compression, larger ring gap, and all that, I have way more oil vapors/oil in intake, than the average car. The sealed RX catch can with 3/8" fittings just cant keep up. It catches half the oil, but the other half still gets into the intake.
Other problem is I'm going to be using a single turbo soon. As I said before I needed bigger and better flowing fittings so I'm going to use -10 AN fittings and hose. For me to have fresh air going in I'd need a super large check valve so the boost couldnt reverse the air flow, that I dont feel like finding. Plus routing the extra hose and fittings.
You dont absolutely NEED fresh air. I know it keeps the oil from being contaminated as quickly. But the way I see it, this is mostly a track car with a little street time. I put 3,000-4,000 miles on the car per year and I change the oil every 1,000-1,500 miles.
I just dont see the point in running all the extra hose and all that to get fresh air when I change the oil that often. I just want something that will suck the oil vapors out through the intake, then relieve crank case pressure well at WOT. The Draft can, or any of the other MM cans does well at that with the check valve type filter on top of the can.
But the two problems were, with my built 408, higher compression, larger ring gap, and all that, I have way more oil vapors/oil in intake, than the average car. The sealed RX catch can with 3/8" fittings just cant keep up. It catches half the oil, but the other half still gets into the intake.
Other problem is I'm going to be using a single turbo soon. As I said before I needed bigger and better flowing fittings so I'm going to use -10 AN fittings and hose. For me to have fresh air going in I'd need a super large check valve so the boost couldnt reverse the air flow, that I dont feel like finding. Plus routing the extra hose and fittings.
You dont absolutely NEED fresh air. I know it keeps the oil from being contaminated as quickly. But the way I see it, this is mostly a track car with a little street time. I put 3,000-4,000 miles on the car per year and I change the oil every 1,000-1,500 miles.
I just dont see the point in running all the extra hose and all that to get fresh air when I change the oil that often. I just want something that will suck the oil vapors out through the intake, then relieve crank case pressure well at WOT. The Draft can, or any of the other MM cans does well at that with the check valve type filter on top of the can.
If you have the LS6 valley cover with PCV port, that is ideal. You can pull oil vapor from the valley and both valve covers. Run all 3 lines to a junction right before the can.
Since you plan to go turbo, I highly suggest using a big check valve and moving your vac source. Running N/A the manifold vac is ok but not as good as between throttle and air filter. Running turbo, the ideal location is between air filter and turbo.
Since you plan to go turbo, I highly suggest using a big check valve and moving your vac source. Running N/A the manifold vac is ok but not as good as between throttle and air filter. Running turbo, the ideal location is between air filter and turbo.
