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

60Gunner 7th August 2019 14:25

I'd like to keep venting in the cam chest but unless I can figure a way to separate the oil before getting to the fitting I'll probably stay in the heads.

Hippysmack 7th August 2019 14:44

Quote:

Originally Posted by 60Gunner (Post 5768234)
I'd like to keep venting on the csm chest but unless I can figure a way to separate the oil before getting to the fitting I'll probably stay in the heads.

Are you getting excess oil at the fitting or just drops?

60Gunner 7th August 2019 15:01

Drops of mayonnaise. I get a couple drops after shut down out of the hose and the inside of the hoses and krankvent are coated. I'm sure the gauze of the stock breathers in the heads helps a lot. If I could come up with something inside the cover to separate the oil from the mist it would help tremendously. Just not sure I can make that setup from the older covers work.
I wonder too whether the moisture content is higher in the cam chest where as in the heads the high heat burns/evaporates a lot of it.

Hippysmack 7th August 2019 15:06

Try turning the 90 up?

dieselvette 7th August 2019 15:08

So I was incorrect to say the pump picks up crankcase oil before the gearcase oil - makes more sense to pick up the cam oil in the smaller port anyway - this distinction may or may not be trivial.

Keep in mind that whether or not there is oil at the scavenge port, the pump is moving something. I don't think a p-d pump can really cavitate in the traditional sense (unless it's really worn). In fact id you have a diesel engine in a car you probably have a vaccum pump for accessories - and it would use this same pump design and be fed a tiny amount of oil and be unstoppable.

So the pump is always pulling a given volume through the scavenge port whether oil is present or not. When oil is not present, the volume of air it moves may or may not be trivial.

What I mean by "dead end" is that since it ends at the pump, the pump determines what moves through the port, and CC pressure has little bearing on that movement or the volume that is moved. CC pressure/vac only affects it indirectly by causing the oil to actually be there (or not).

I think what Bustert explained about oil/air/splash movement makes sense. Keeping in mind that really the only "splash" lubrication is for the cylinder walls, correct? All other parts are intentionally lubricated by oil forced by the supply pump.

The amount of oil moved by the supply pump hasn't changed for many years. It's just a matter of where it goes - CC vs cam chest vs bypass etc. The extra amount to CC on 04-up with the squirters may or may not be a contributing factor in wetsumping or increasing the scavenge capacity. Sure wetsumping problems may have increased with design changes over the years, necessitating the more scavenge volume, but the squirters were only one thing of many.

dieselvette 7th August 2019 15:32

Hippy - oil puking out the breathers - I don't think is directly caused by wetsumping or CC pressure, sort of. The reason for oil coming out is one of two things:
1) To much overall *flow* out the breathers. Higher flow is due to too much air getting IN the engine which has to come back out. (look for the usual offenders) In this case you would probably measure higher CC pressure, but not necessarily, depends on breathers.
2) A phenomenon where a fast in/out pulses essentially "pumps" oil along with air out the breathers. This is not likely to happen if the umbrellas are in good condition and the oil drains in them are functional.

(Not to be confused with 60Gunner's concerns with baffling the vent hole).

dieselvette 7th August 2019 16:03

"That being said, wouldn't the slotted wheels both create more windage and pick up more oil in suspension?
It looks obvious to me that higher positive pressure (from whatever source) would sling oil higher and pull more oil in rotation.
Making the air/oil mix more dense as it is blown into the cam chest."

As fast as the wheels are spinning, there is no way they pick up oil, it all flies off almost instantly. There is the oil coming from the bearings which obviously slings out, but the only way they sling more than that is if was submerged due to excess oil laying in the bottom (classic wetsumping condition)

The fins/grooves make it essentially a fan blade to blow oil away from it - mostly towards the rear because of direction it's spinning and the baffle underneath it.

Hippysmack 7th August 2019 16:13

True and also keep in mind that air is compressable.
So you shouldn't get the same volume of air that you'd get while pumping oil.

We speak in terms of cavitation more thru the feed side of the pump.
The FSM gives instructions (on the older pumps) to remove the oil pressure switch and spin the engine over until oil comes out to prime the pump.
There have been instances where the enigne was running but no feed oil was flowing due to cavitation.
Oil to the feed side is a given thru gravity from the tank.
So if all else fails, sitting for a while will eventual trickle oil into the feed gears.
The problem occurs when the pump has been removed, cleaned and not oiled inside before installation.
(which in later FSMs, it just says to oil the pump before installation)

Transfer that thinking over to the return side of the pump.
There is no gravity feed to the scavenge gerotors.
In fact the gravity direction has been reversed (from pump to sump).
So it's a given upon startup that there will be air in the scavenge passage to the pump first before oil.
However, the pump sits below the drilled horizontal passage and the hydo seal isn't broken due to gravity back to the sump.
Also with the return line verticle from the tank to pump, oil in the return line falls back to the gerotors especially during cavitation of the return side, that will also help the hydro deal while running or sitting still.

Also with the cam chest port in the top of the oil pump going to the same gerotor area (even though separately routed there) there has been a concern for CC pressure entering the cam port of the pump and causing the sump port to cavitate.
(has been discussed along with the 5 speed to 4 speed oil pump conversion)
The obvious intake volume of each port into the oil pump suggests that can't happen unless there is cavitation in the sump passage first.

Splash lube is essential, from the up and down movement of the connecting rods, crankshaft and pressure generated under the pistons on downstroke serves to lubricate;
Cylinder walls
Pistons, piston pins
Cam gears and bushings
Main bearings

Forced pump feed is only going to the lifters and rod bearings (and piston unders in 04+)
Everything else is either gravity or splash lubed.
Splash lube also includes what flys off the wheel assembly as well as cam gear teeth.
The rocker box is fed from lifter pump force.

Quote:

Originally Posted by dieselvette (Post 5768243)
Hippy - oil puking out the breathers - I don't think is directly caused by wetsumping or CC pressure, sort of. The reason for oil coming out is one of two things:
1) To much overall *flow* out the breathers. Higher flow is due to too much air getting IN the engine which has to come back out. (look for the usual offenders) In this case you would probably measure higher CC pressure, but not necessarily, depends on breathers.
2) A phenomenon where a fast in/out pulses essentially "pumps" oil along with air out the breathers. This is not likely to happen if the umbrellas are in good condition and the oil drains in them are functional.

(Not to be confused with 60Gunner's concerns with baffling the vent hole).

Everything we've discussed affects CC pressure even if you don't have oil puking.
1. Explain why there is too much overall flow and you will eventually get back to too dense of oil/air mist.
Then ask yourself how it got that dense.
2. Fast in/outs pump more oil into the air just like fast on/off throttle pumps more oil into the sump.
It's not as likely to happen on OEM engines with functioning breathers but it according to XLF poll does happen a lot more to upgraded engines with brand new OEM breathers.
The breathers didn't change but under the piston volume did.
Ask yourself why.
Also OEM engines of all years are subject to puking for different reasons and as you mentioned, design has changed but the problem still exists.
Ask yourself why.

Hippysmack 7th August 2019 16:18

Quote:

Originally Posted by dieselvette (Post 5768250)
"That being said, wouldn't the slotted wheels both create more windage and pick up more oil in suspension?
It looks obvious to me that higher positive pressure (from whatever source) would sling oil higher and pull more oil in rotation.
Making the air/oil mix more dense as it is blown into the cam chest."

As fast as the wheels are spinning, there is no way they pick up oil, it all flies off almost instantly. There is the oil coming from the bearings which obviously slings out, but the only way they sling more than that is if was submerged due to excess oil laying in the bottom (classic wetsumping condition)

The fins/grooves make it essentially a fan blade to blow oil away from it - mostly towards the rear because of direction it's spinning and the baffle underneath it.

I'm not saying the slots in the wheels actually pick up oil in them.
I'm saying they add extra windage that pulls more oil up from the back of the sump wall.

Hippysmack 7th August 2019 16:27

I'll also go so far as to say a bigger problem occurs when oil accumulates on top of the factory windage tray (top of the 'X' in the pic below) between it and the wheels.
Rotating oil there easily slows down rotation.
Is that where oil churns and aerates the most?

Quote:

Originally Posted by rubine (Post 5119283)

edit:
Tore, how much did this help?
Quote:

Originally Posted by norseXL (Post 5011945)



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