More Oil Catch Can Contents
#41
I have both the stock ports in the valve cover plus a vent port in the side of the block going to my baffled catch can.
I also have a drain back from the catch can that goes to the very bottom of the sump below the oil level. I think Id rather change my oil more often to keep contaminants from building up than worry about draining the catch can all the time. The water and fuel in the oil should be more volatile so I’m hoping much of it gets sucked out as vapor leaving mostly condensed oil behind.
Bob
#42
Having said that, even if the crankcase absolute pressure were dropped by say 2 psi (in the case of the slash cut on the Honda), that's about a 15% reduction and a 15% reduction in internal aero drag which may be what, <2% of the total output?
#43
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Replace the filter on your catch can with a hose going to the check valve/slash tube in the exhaust. It needs to be sealed in order to pull a vacuum on your crank case.
I have both the stock ports in the valve cover plus a vent port in the side of the block going to my baffled catch can.
I also have a drain back from the catch can that goes to the very bottom of the sump below the oil level. I think Id rather change my oil more often to keep contaminants from building up than worry about draining the catch can all the time. The water and fuel in the oil should be more volatile so I’m hoping much of it gets sucked out as vapor leaving mostly condensed oil behind.
Bob
I have both the stock ports in the valve cover plus a vent port in the side of the block going to my baffled catch can.
I also have a drain back from the catch can that goes to the very bottom of the sump below the oil level. I think Id rather change my oil more often to keep contaminants from building up than worry about draining the catch can all the time. The water and fuel in the oil should be more volatile so I’m hoping much of it gets sucked out as vapor leaving mostly condensed oil behind.
Bob
valve cover to catch can
catch can drain to sump
catch can also vents to slash and check valve
#44
Agree on the dubiousness of the claim that an additional few psi of pressure differential between the top and bottom of the pistons on top of the compression and power stroke pressure would make much of a difference.
Having said that, even if the crankcase absolute pressure were dropped by say 2 psi (in the case of the slash cut on the Honda), that's about a 15% reduction and a 15% reduction in internal aero drag which may be what, <2% of the total output?
Having said that, even if the crankcase absolute pressure were dropped by say 2 psi (in the case of the slash cut on the Honda), that's about a 15% reduction and a 15% reduction in internal aero drag which may be what, <2% of the total output?
I think it would be worth maybe 5, if the suction was very good!
#48
I will be putting the fitting in the exhaust after the Wide band so I’m not worried about that.
Bob
#51
My understanding of PCV is not very good, but I'm close to Bob in that I'm mostly interested in keeping oil vapors out of my intake tract, and out of my cylinders.
For my last setup, I did as many here seem to, put a breather filter on the cam cover, stock PCV in place. That kept my intake dry for over a year, but over time the filter saturated with oil, leaked, and otherwise put a nice film of oil in a lot of places in the bay.
On my current setup, I'm thinking of doing something different - run a hose from the valve cover breather to one port of a catch can, and put a breather on the other port of the can. Thought being it would trap the vapors in the can and stop the breather clogging. If anyone thinks that's dumb, let me know. This being mturbo I don't really need to ask I guess.
This exhaust vacuum source seems like a cure for turbo oil drain/ring sealing under boost, I'd imagine there was no need for a pcv at that point?
Unfortunately I'd rather not run without a cat. The air pump idea would solve that, but cost, weight, packaging, and complexity make that less appealing.
For my last setup, I did as many here seem to, put a breather filter on the cam cover, stock PCV in place. That kept my intake dry for over a year, but over time the filter saturated with oil, leaked, and otherwise put a nice film of oil in a lot of places in the bay.
On my current setup, I'm thinking of doing something different - run a hose from the valve cover breather to one port of a catch can, and put a breather on the other port of the can. Thought being it would trap the vapors in the can and stop the breather clogging. If anyone thinks that's dumb, let me know. This being mturbo I don't really need to ask I guess.
This exhaust vacuum source seems like a cure for turbo oil drain/ring sealing under boost, I'd imagine there was no need for a pcv at that point?
Unfortunately I'd rather not run without a cat. The air pump idea would solve that, but cost, weight, packaging, and complexity make that less appealing.
#54
I'd considered this way back, but from what I understood the tube needed to be located near the beginning of the exhaust system to generate good vacuum. That meant ahead of the cat, which is out of the question for those who have emissions (and maintain that standard annually).
#55
If this were doable then installing this is a no brainer for me. But as m2 said it needs to be further upstream to generate good vac. Since I'm running no cat I'd like to have it at least behind my sensor. Anyone think I'd get good enough vac behind my sensor?
Split's old DP which I'm using:
Split's old DP which I'm using:
#56
Yes you will get ******* good vac there, shesssh,
if you are worried about the crude getting on the cat put a catch can between the Valve cover and the exhaust pipe to catch the crude buildup
The whole point of the catch can system was to keep the crude from being pushed back into the intake system imo, normally manufactures use the engines own vacuum to pull vacuum in the crankcase and for emission reasons to reburn the crap that comes out of the crankcase.
What I don't get is why people put on a catch can, vent to atmo, why not help the engine breath easier as well, put a vacuum into the crankcase, worried about oil going though exhaust? put the catch can on it than, thats why people used
Pulling a vacuum has been going on for few decades now, various ways to do it as well, exhaust, vacuum pump ( elec \ belt ), engine itself, etc
once my miata is running again ( timing belt ) I will grab a video with a boost ( vacuum+pressure) gauge attached to the line and drive it about tad showing it.
if you are worried about the crude getting on the cat put a catch can between the Valve cover and the exhaust pipe to catch the crude buildup
The whole point of the catch can system was to keep the crude from being pushed back into the intake system imo, normally manufactures use the engines own vacuum to pull vacuum in the crankcase and for emission reasons to reburn the crap that comes out of the crankcase.
What I don't get is why people put on a catch can, vent to atmo, why not help the engine breath easier as well, put a vacuum into the crankcase, worried about oil going though exhaust? put the catch can on it than, thats why people used
Pulling a vacuum has been going on for few decades now, various ways to do it as well, exhaust, vacuum pump ( elec \ belt ), engine itself, etc
once my miata is running again ( timing belt ) I will grab a video with a boost ( vacuum+pressure) gauge attached to the line and drive it about tad showing it.
#57
My catch can system.
-8 lines to the valve cover vents. Holes have been enlarged in the baffles in the valve cover.
Exhaust side valve cover vent goes into a small manifold that tees into a -10 line going to a port put in the block venting the lower crank case before going to the catch can.
-8 line going from PCV port to catch can.
Catch can is baffled with and a pot scrubber is used. Blow-by has to go down through the pot scrubbers then back up the central tube to get out.
-10 line return drain goes to very bottom of the oil pan.
The filter breather will be replaced with a -10 line going to a check valve and slash tube in the exhaust pulling a slight vacuum on the system.
Bob
-8 lines to the valve cover vents. Holes have been enlarged in the baffles in the valve cover.
Exhaust side valve cover vent goes into a small manifold that tees into a -10 line going to a port put in the block venting the lower crank case before going to the catch can.
-8 line going from PCV port to catch can.
Catch can is baffled with and a pot scrubber is used. Blow-by has to go down through the pot scrubbers then back up the central tube to get out.
-10 line return drain goes to very bottom of the oil pan.
The filter breather will be replaced with a -10 line going to a check valve and slash tube in the exhaust pulling a slight vacuum on the system.
Bob
#59
Correction: FWIW here's my 1/4 NPT port, for 1/2" hose. Ignore the black hose, it's not part of the system.
I enlarged the tiny internal blowby hole. Described here
https://www.miataturbo.net/engine-performance-56/cam-cover-blowby-flow-crankcase-pressure-tiny-hole-modification-54742/
I enlarged the tiny internal blowby hole. Described here
https://www.miataturbo.net/engine-performance-56/cam-cover-blowby-flow-crankcase-pressure-tiny-hole-modification-54742/
Last edited by JasonC SBB; 01-31-2011 at 12:56 PM.
#60
FWIW here's my 1/2 NPT port. Ignore the black hose, it's not part of the system.
I enlarged the tiny internal blowby hole. Described here
https://www.miataturbo.net/showthread.php?t=54742
I enlarged the tiny internal blowby hole. Described here
https://www.miataturbo.net/showthread.php?t=54742
Bob