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-   -   Sportster Crankcase Pressure / Engine Breathing / Wetsumping and Mods (http://xlforum.net/forums/showthread.php?t=2073932)

Hippysmack 26th July 2019 17:50

I read the Indian article and I mostly agree.
But the op didn't address scavenging.
I don't know how and Indian does that, but higher vacuum does affect Sportster scavenging.

60Gunner 26th July 2019 18:24

I'm just talking about how they ran the vent line from the cover not the additional venting.
So why DID they move the Venting if not to make it easier to vent to the AC? I haven't noticed any scavenging issues.
I'm going to run it hard today just to be sure before making my final changes.

60Gunner 26th July 2019 19:14

The majority of people venting to atmosphere are running breather bolts with much larger openings than the stock ones. Larger than I am actually since I'm only running one fitting.

Hippysmack 26th July 2019 19:20

Quote:

Originally Posted by 60Gunner (Post 5765310)
So why DID they move the Venting if not to make it easier to vent to the AC?

Go back to the drawing in post 226.
Venting to the heads thru the restrictions in the lifter blocks creates a certain more back pressure in the crankcase.
This would increase the push toward scavenge oil.
One of the biggest problems oiling wise the MoCo was having was in controlling oil scavenging.

86-90 engines had a tendency to flood the crankcase with oil.
In 86, they increased the feed gerotors for the addition of the oil filter in the feed side of the system as opposed to the filter on the return side from 85<.
They did not increase the size of the scavenge gerotors.
They also added a 30-35 psi pressure relief in the filter pad that would dump excess oil pressure into the cam chest-then crankcase sump.

The vent change in 91 would increase scavenging.
I'm sure that's not the only reason but it should be considered.
It makes no sense for the EPA to have been the cause for the head vents due them venting to the A/C from 79 on.
It had to be a mechanical or performance issue.

Quote:

Originally Posted by dieselvette (Post 5765206)
Watched the video - thanks for posting the link. Betting the sporty has a tiny tiny air leak somewhere that's just enough to bleed off the blowby.

But if you can be 100% certain your system has no air leaks, perhaps that is a valid way to test for blowby? No - because there's no way you can be 100% certain, so it is subjective.

Confused.
As in the video, that is a properly running Sportster engine that is being tested.
Not sure where you see an air leak?
You can be certain that you will always have blowby.
The variable is how much and that varies with every single engine.

-----------------

The air volume in the oil tank is too small to vent the entire engine air there because all of that oil is sitting below it.
The volume overpowers the space is why the oil is brought up and out of the oil tank if used as a breather point.
As 60Gunner mentioned, a pressure relief valve there would open only when the pressure gets too high.
And then close when the set pressure was below.
This is apparently what the MoCo did in 2010 with the 10 psi pressure reief built into the tank.
The pressure relief only opens for a short time and only if the pressure rises past the pre-set cracking pressure of the relief valve.
I believe this was there 'fix' for 04-09 exploding oil tanks.
03 and prior tanks are steel which can take the pressure (which is transfered back to the cam chest and manipulates the breathing systen from there).

Condensation exists no matter where the vent is located.
The key to not collecting goop is to not allow the goop anywhere to collect.
See next post.

With the two separate cylinders, CC pressure (air and particulary oil mist) builds in each.
If you vent one but not the other, you're creating more restriction in the other that has to go back down and into the first top end path to leave.
Notice, both top end constructions are identical.
Changing one path and not the other could change total dynamics of each acting as a unit together.

I believe the krankvent is a swapout for pressures.
The head breathing system creates higher pressure inside. Let's say "X+1".
Remove them from the heads and you now have "X" pressure.
Vent out the cam chest and ad the krankvent with the beefier umbrella and you now have "X+1" again.
There is a whole lot more to that but the just is trading one way for another.
This may be one reason why the breather valve itself can help or hinder.
But Aaron's testing says you get "0" HP gains from different vents.
So the trade-off between them doesn't get you much.
It's just different.
Gunner's results, even though refreshing, are a combination of many changes that just occurred in his engine.
The vent in the cam chest instead should have lowered overall CC pressure through the re-directing of the air path (away from the restrictions mentioned in my previous post).
In turn, the krankvent may restrict pressure a bit before opening as mentioned earlier (raising CC pressure a bit).
The size, length and routing of his vent line is also a restriction in the path.
A catch can may also add to the outlet restriction.

The oil pump doesn't have to be full of oil to have prime for suction.
It simply has to have a hydraulic seal.
Even oil mist can provide that hydraulic seal if moving fast enough.

Hippysmack 26th July 2019 19:24

Quote:

Originally Posted by 60Gunner (Post 5765328)
The majority of people venting to atmosphere are running breather bolts with much larger openings than the stock ones. Larger than I am actually since I'm only running one fitting.

Yes and if did a survey of each one's engine setups, you'd find it wasn't just the bolt hole size that made the difference good or bad.
The whole system adjusts to each different change made.
The big picture is a lot harder to analyze with so many different variables at play.

Hippysmack 26th July 2019 19:47

Vent Outlet Above vs Below the Head Vents
 
There has been debatable ways to route the vent lines off the heads when doing air cleaner mods.
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;
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 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 and become an emulsified goop.
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.
If the vent lines are piped above the exit point in the heads, oil out of suspension will not drain back into the engine.
The oil would have to run uphill to get from the heads to the rocker boxes and into the lower end.
So there is no functional advantage to running the lines higher than the head vents.
http://sportsterpedia.com/lib/exe/fe...hippysmack.jpg

http://sportsterpedia.com/lib/exe/fe...hippysmack.jpg

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 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.

Kuryakyn or Other High Mount Breather Bolts:
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.
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.
Or the trapped oil may simply be blown out the vent lines in globs.


Vent lines mounted high tend to promote a mixture of oil and condensation settling near the head connection of the hose.

http://sportsterpedia.com/lib/exe/fe..._by_scar55.jpg

http://sportsterpedia.com/lib/exe/fe..._by_scar55.jpg

Horseshoe Tube:
The horseshoe breathers that take the outlet from the breather bolts upwards tend to clog with foamy oily gunk.
It's a low pressure output with not enough to push the sludge upwards and around the bend.
This means the breather bolts are swimming in this gunk and if there is a small leak there is plenty to leak.
Fitting a breather where the outlet from the bolts goes downwards alleviates this.
Nylon, copper or brass washers will deform slightly under pressure and seal things better also.

With the horseshoe tube mounted high and only one end with a vent line at the banjo bolt, condensation and oil can emulsify in the non-vented end.
In the pic below, the air in the rear head has to travel up to the front.
When the engine is shut off, condensation / unsuspended oil falls back to the low spot (in this case the tube connection at the rear head).
Goop collects there which either has to re-suspend after startup, heat up and move out into the vent.
It can also come back down the horseshoe towards the engine, and collect at the breather valve.
If there is a filter on the end of the vent line, this collected goop can be sent to and clog the filter as well.
Some appear to be OK with this as it is seen as better to be outside than inside the engine.
However, the goop (emulsified oil) is a restriction to crankcase pressure leaving the engine until it is cleared.

http://sportsterpedia.com/lib/exe/fe...hippysmack.jpg

http://sportsterpedia.com/lib/exe/fe...hippysmack.jpg

Horseshoe tube, high mount / vent line in front.
http://sportsterpedia.com/lib/exe/fe...kbehringer.jpg

Rear bolt covered in sludge.
http://sportsterpedia.com/lib/exe/fe...kbehringer.jpg

Filter mounted high will receive built up sludge.
http://sportsterpedia.com/lib/exe/fe...y_austinxl.jpg

Vent lines mounted lower than the head vents allow oil / condensation to leave the heads.

This way, sludge can form on each side of filter.
http://sportsterpedia.com/lib/exe/fe...ow_by_beuz.jpg

This way promotes less sludge buildup.
http://sportsterpedia.com/lib/exe/fe..._ixl2relax.jpg

The sludge doesn't get there at once.
To begin with, it's just a slight mist. The restrictions to the vent line (including a filter on the end) allow the mist to glob.
Also, the healthier your engine breathing, the less problems you'll have with the sludge.
But sludge will form even in the healthiest conditions depending on how the vents are routed.

60Gunner 26th July 2019 20:34

So would running the line up in my case be good or not? It's obviously downhill all the way and not havi g to go up the heads but on the other hand it's best to get it out too. In which case just leave it like it is.

Toejam503 26th July 2019 21:02

The reason the breathers were exited into the ac is to keep from getting into the atmosphere. It would then be pulled into the combustion chamber and burned and then the EPA can measure it at the tailpipe. I don't think they wanted it to go to ground simply because the EPA considers this pollution and can create safety concerns on slippery roads.
Back in the days of Blue Skies and Dirt Roads, everything was great.
(Caution: If you think this is wrong, Pay No Attention)

Hippysmack 26th July 2019 21:03

That is the question.
We have proof of how and where sludge is formed.
We don't have data of the implications of it's presence.

It looks ugly in it's transformed state.
But, it's transformed state is what has been presented in advertisement as why you need this or why you need that.
Does it cause a problem or is it just part of the normal process?
I can't answer that yet.

I can say, the MoCo did not to allow this sludge to build with the design of moving the air mist straight out of the heads on 91 Up models.

I haven't come across any modded vent lines downward that the owner said it never dripped oil.
On the other hand, if you raise the vent line horizontal as I mentioned earlier, you will still have condensate settle past the krankvent.
In summary, using a vent line out of the engine in any configuration will not stop oil drips.
You can minimize sludge buildup by strategic line routing.
The rest is up to your personal preference. :)

Hippysmack 26th July 2019 21:11

Quote:

Originally Posted by Toejam503 (Post 5765356)
The reason the breathers were exited into the ac is to keep from getting into the atmosphere. It would then be pulled into the combustion chamber and burned and then the EPA can measure it at the tailpipe. I don't think they wanted it to go to ground simply because the EPA considers this pollution and can create safety concerns on slippery roads.
Back in the days of Blue Skies and Dirt Roads, everything was great.
(Caution: If you think this is wrong, Pay No Attention)

I understand the reasoning of venting to the A/C.
But it didn't stop the problem.
Many times on a hot summer day, road grease seeps into asphalt.
The roads are dry to ride on.
This is mostly from autos leaking oil even today.
I've been sitting at the red light when a pop-up shower swings by.
The car in front of me eases on as usual when the light turns red.
His rear tires are riding on the dry space under the car.
Mine are riding in the wet spot behind his and I spin.
That oil didn't get there from a motorcycle.

Yet the motorcycle suffered the most of the two from the knee jerk reaction of the powers that be.


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