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techtalk:ref:engmech05 [2019/07/18 18:51] hippysmack [Vent Outlet Above vs Below the Head Vents] |
techtalk:ref:engmech05 [2019/10/12 03:56] hippysmack |
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However, exact line routing comes down to function over fashion. \\ | However, exact line routing comes down to function over fashion. \\ | ||
While it may look better or cleaner for the lines to be routed above the air cleaner; \\ | While it may look better or cleaner for the lines to be routed above the air cleaner; \\ | ||
- | Doing so doesn't make for good functioning of the breather system. \\ | + | Doing so doesn't necessarily make for good functioning of the breather system. \\ |
+ | That also can be debated. \\ | ||
The air / oil that gets blown out is a combination of crankcase pressure and engine blowby. \\ | The air / oil that gets blown out is a combination of crankcase pressure and engine blowby. \\ | ||
- | Blowby gasses produce a corrosive vapor which doesn't need to go back into the engine. \\ | + | The argument is blowby gasses produce a corrosive vapor which doesn't need to go back into the engine. \\ |
- | It'll simply pool in the heads / vent lines. \\ | + | It'll simply pool in the heads / vent lines and become an emulsified goop. \\ |
Mounting vent lines higher than the head vents is counterproductive to quick air/oil/condensate removal. \\ | Mounting vent lines higher than the head vents is counterproductive to quick air/oil/condensate removal. \\ | ||
+ | It's the quick removal that helps prevent sludge buildup. \\ | ||
As you can see from the drawings below, expelled air leaves the rocker boxes by running downhill to get out the vent holes in the heads. \\ | As you can see from the drawings below, expelled air leaves the rocker boxes by running downhill to get out the vent holes in the heads. \\ | ||
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The air coming from the head vents has fine water condensation and oil mist particles in suspension with it. \\ | The air coming from the head vents has fine water condensation and oil mist particles in suspension with it. \\ | ||
- | When that air cools, the oil mist falls out of suspension and collects in the vent lines. \\ | + | When that air cools, the oil mist falls out of suspension and collects in the vent lines and mixing with unsuspended oil droplets. \\ |
Pointing the vent lines straight into the A/C (OEM) or down into a catch can allows the oil out of suspension to leave the vent lines. \\ | Pointing the vent lines straight into the A/C (OEM) or down into a catch can allows the oil out of suspension to leave the vent lines. \\ | ||
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However, pointing the vent lines upward of the head vents allows oil out of suspension to collect in them. \\ | However, pointing the vent lines upward of the head vents allows oil out of suspension to collect in them. \\ | ||
Once there is enough liquid oil in the upward breather tubes it will act just like the trap under your sink. \\ | Once there is enough liquid oil in the upward breather tubes it will act just like the trap under your sink. \\ | ||
- | It may block air from getting out until the engine (on startup) builds enough pressure to push the liquid and bubble up to the top. \\ | + | It may restrict or block air from getting out until the engine (on startup) builds enough pressure to push the liquid and bubble up to the top. \\ |
So it may affect crankcase pressure slightly until the lines are cleared. \\ | So it may affect crankcase pressure slightly until the lines are cleared. \\ | ||
Or the trapped oil may simply be blown out the vent lines in globs. \\ | Or the trapped oil may simply be blown out the vent lines in globs. \\ | ||
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To stop a leak, you may be tempted to tighten the bolts even more. \\ | To stop a leak, you may be tempted to tighten the bolts even more. \\ | ||
This could result in breaking the bolt. \\ | This could result in breaking the bolt. \\ | ||
+ | |||
+ | On 04-up heads, changing to aftermarket breather bolts means using bolts with the bigger I.D. (91-03) style bolts. \\ | ||
+ | The results of using the bigger holed bolt would be a slower rate of outflow and less positive crankcase pressure on a stock motor. ((Hippysmack of the XLFORUM http://xlforum.net/forums/showthread.php?t=2073932&page=4)) \\ | ||
+ | But the timing of the upstroke is the same which then pulls a vacuum. \\ | ||
+ | The umbrella valve will close down only when inside air pressure is lower than outside air pressure. \\ | ||
+ | If the inside pressure can't get out fast enough before piston upstroke happens the umbrella may 'float' or not close all the way. \\ | ||
+ | If the umbrella floats, X amount of extra air is pulled in until it does close. \\ | ||
+ | (on top of what didn't get completely out on the last downstroke = more air in the engine on the next downstoke = oil puking out the breather). \\ | ||
+ | How much slower the bigger bolt hole yields will vary with different engines. \\ | ||
+ | |||
+ | However, the smaller holed bolts were designed to OEM specs internally. \\ | ||
+ | If you've upgraded to bigger pistons, there will be more positive pressure displaced out the breathers on downstroke. \\ | ||
+ | This may negate the need for higher pressure generated by the smaller holed bolts. \\ | ||
+ | This may be something you'd want to watch since there isn't sufficient data to prove one way or the other. \\ | ||
{{:techtalk:ref:engmech:breather_mod_2_by_hagen.jpg?direct&300|}} ((photo by Hagen of the XLFORUM http://xlforum.net/forums/showthread.php?t=146084&page=11)) {{:techtalk:ref:engmech:ds_breather_bolt_by_hagen.png?direct&300|}} ((photo by Hagen of theXLFORIM http://xlforum.net/forums/showthread.php?t=692845)) {{:techtalk:ref:engmech:broken_banjo_bolt_by_scout99.jpg?direct&200|}} ((photo by Scout99 of the XLFORUM http://xlforum.net/forums/showthread.php?t=28299)) | {{:techtalk:ref:engmech:breather_mod_2_by_hagen.jpg?direct&300|}} ((photo by Hagen of the XLFORUM http://xlforum.net/forums/showthread.php?t=146084&page=11)) {{:techtalk:ref:engmech:ds_breather_bolt_by_hagen.png?direct&300|}} ((photo by Hagen of theXLFORIM http://xlforum.net/forums/showthread.php?t=692845)) {{:techtalk:ref:engmech:broken_banjo_bolt_by_scout99.jpg?direct&200|}} ((photo by Scout99 of the XLFORUM http://xlforum.net/forums/showthread.php?t=28299)) | ||
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This resistance can add to goop in the line / filter later. \\ | This resistance can add to goop in the line / filter later. \\ | ||
- | The filter does not keep debris from coming back into the engine. ((V of the XLFORUM http://xlforum.net/forums/showthread.php?p=2087347)) \\ | + | The filter does not keep debris from coming back into the engine. ((Folkie of the XLFORUM http://xlforum.net/forums/showthread.php?p=2087347)) \\ |
If anything can get back in, it means your umbrella valves are shot. \\ | If anything can get back in, it means your umbrella valves are shot. \\ | ||
There will be quite a bit of oil coming out the breathers, and all sorts of stuff going back in. \\ | There will be quite a bit of oil coming out the breathers, and all sorts of stuff going back in. \\ | ||
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If your breather valves are in good order, nothing can get back through them. \\ | If your breather valves are in good order, nothing can get back through them. \\ | ||
+ | The exception to this would be 91-03 engines with the middle rocker box umbrella valve with the tiny hole behind it. \\ | ||
+ | The tiny holes next to (and slightly lower than) the umbrella valves are for draining the separated oil back into the rocker box. \\ | ||
+ | However, there isn't large enough suction back on the vent line to pull debris up and into the engine. \\ | ||
+ | |||
===== Filter Placement ===== | ===== Filter Placement ===== | ||
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|Doherty Power Vents with the line routed up then \\ down and attached to the bottom of the frame. ((photo by RIORoosen of the XLFORUM http://xlforum.net/forums/showthread.php?t=146084&page=18))| | |Doherty Power Vents with the line routed up then \\ down and attached to the bottom of the frame. ((photo by RIORoosen of the XLFORUM http://xlforum.net/forums/showthread.php?t=146084&page=18))| | ||
|{{:techtalk:ref:engmech:breather_mod_by_rioroosen.jpg?direct&300|}}| | |{{:techtalk:ref:engmech:breather_mod_by_rioroosen.jpg?direct&300|}}| | ||
+ | |||
+ | |Hayden KVP38 breather valve, used with the \\ [[techtalk:ref:engmech05d|Deimus Mod]] (cam chest breather conversion). ((photo by 60Gunner of the XLFORUM http://xlforum.net/forums/showthread.php?p=5763918#post5763918))| Hayden breather opened up. ((photos by leucadiaGuit of the XLFORUM http://xlforum.net/forums/showthread.php?t=2004869 cropped by Hippysmack)) || | ||
+ | |{{:techtalk:ref:engmech:deimus_mod_8_by_60gunner.jpg?direct&300|}}|{{:techtalk:ref:engmech:hayden_krankvent_3_by_leucadiaguit_-_cropped.jpg?direct&300|}}|{{:techtalk:ref:engmech:hayden_krankvent_2_by_leucadiaguit_-_cropped.jpg?direct&300|}}| | ||