wet sump engine oil control, a thread.

[ericjon262]

I wanted to start a serious discussion on oil control, Engine Masters ran a test a while back, where they picked up a not insignificant amount of power on an engine dyno, simply by removing oil from the sump. A static engine dyno does not have the same limitations as a moving vehicle, but the concept of oil control is still very relevant. this particular episode had me interested in improving oil control, then, Will, Posted this in the dimpled piston thread, I thought it warranted it's own thread for discussion.

I know I've followed up with about diddly on the dimpled pistons item...

But here's a post on oil I found a few years back, forgot about, then stumbled on again purely by accident over the weekend:

https://www.speed-talk.com/forum/viewto ... 53#p423853

firstly, this thread states that film strength is the gold standard for wear protection, and then goes on to show what oil analysis showed for film strength of various oils, really good info IMO. this quote in particular to me, is very important

You don't need any oil pressure higher than the old rule of thumb of 10 psi for every 1,000 rpm. So, there is no reason to run thicker oil just to up the oil pressure. Oil that is thicker than needed to meet the rule of thumb pressure, will only reduce flow/lubrication for no reason. Remember oil flow is lubrication, but oil pressure is NOT lubrication, it is only a measurement of resistance to flow.

I don't necessarily jump on with the 10 PSI per 1000 RPM, there's a ton of variables at play that change those numbers, but it's still typically a fairly safe bet. The key point of the quote to me, is the part I made bold, pressure is resistance to flow, if you dead head the oil pump, you'll have plenty of pressure, but no flow. I think we all know where that story goes...

Personally, I think good oil control will improve the longevity of the engine, as well as performance, so how do we control the oil? I think the thread can be broken down to three major ideas

1. oil pressure via the oil pump and accumulators.
2. controlling drainage to the sump.
3. controlling windage.
(there is alot of blurring between 2/3)

I don't consider myself to be an expert, but I will share information as I can and hope that this thread generates valuable discussion on the topic.
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Oil pumps:

All oil pumps for lubrication service that I have ever seen, are positive displacement, meaning that for each cycle the pump undergoes, it will move the same amount of fluid, regardless of pump speed until the pump cavitates, pumps the sump dry, or breaks. in automotive applications, we typically see two types of oil pump, the gear pump, and the gerotor pump, which technically, is still a gear pump, it's just a little different.

gear pumps use two or more intermeshed gears, the gears trap oil in the roots of the gear teeth, between the walls of a casing, which then moves the oil to the discharge side.



this operation is identical to that of a Roots style supercharger. The volume of oil moved per cycle is controlled by the size of each tooth of the gears, and the height of the gears. these pumps are common on small and big block Chevy engines, as well as 60 degree V6's, among a host of others.

Gerotor(Generated rotor) pumps are a still a gear type positive displacement pump, but they operate in a slightly different manner. Gerotor pumps use two gears, one is an internal tooth gear, and the other an external tooth, the external tooth gear having one less tooth than the internal tooth gear. the internal tooth gear is typically driven by the external tooth gear, and as the two gears rotate, they produce a expanding void space where the oil is drawn into the pump, as the gears rotate, the expansion area reaches a maximum, and as the gears rotate, the area gets smaller forcing the oil through a discharge port. These types of pumps are common on Northstar V8's, small block fords, LS V8's, and many others. I suspect that gerotor pumps have an efficiency advantage over other gear pumps, as they seem to be more common on newer engines than gear pumps are. Flow can be increased in a gerotor pump by either making the gear teeth bigger, or, making them taller, the same as the gear pumps mentioned above.



as mentioned above, positive displacement pumps move a specific volume with every cycle, the downside to this, is that they can create oscillations in pressure, particularly lower operating speeds. these oscillations can be reduced in two primary ways, option one with a gear type pump, is to increase the number of gear teeth, this is observable with the GM 60 degree V6 with and without Variable cam timing. At one point, I took apart a LZ9, and LX9 pump, what I had found, was that although the frame/case of the LZ9 pump was much larger than the LX9 pump, it actually flowed about the same amount of oil, based on the number of gear teeth, and the size of those teeth. the LZ9 pump had a significantly higher tooth count, which for a given diameter tooth, meant the teeth had to be smaller, but, the height of the gears was increased, which made up for the smaller teeth, and therefore means the LZ9 pump, while flowing the same amount of oil, should do so, with a more consistent outlet pressure. I suspect, this is because the Variable cam timing system, which uses oil pressure to adjust cam timing, needs a more consistent pressure than the earlier style pumps could output.

the other way to improve oil pump outlet pressure consistency, is to have an accumulator in the system, as the pressure spikes from the pump discharge, the accumulator will absorb some of the spike, and as the pressure drops, the accumulator will discharge some oil to maintain a consistent pressure. this really isn't where we see accumulators typically employed on a car though, typically, we see accumulators employed as a backup device to maintain oil pressure in the event the oil pump pickup becomes uncovered, and the oil pump sucks air, or the oil pump begins cavitating.

it's worth mentioning, cavitation, and sucking air, are not the same thing. cavitation occurs when the oil pump lacks the net required inlet pressure to draw oil into the pump, and forms a vacuum pocket inside the pump, this pocket can become trapped between the gear teeth, and the travel to the pump outlet, where the higher pressure pushes oil towards the vacuum, and back to the pump. instead of out to the oil galleries. sucking air means the pump physically draws in air instead of oil, and pushes air into the oil galleries, neither situation is desirable, and should be considered a goal to eliminate with proper oil control.

I find myself questioning the use of "high volume" oil pumps, yes the dimensions of the pump changed to increase the volume moved with each cycle of the pump, but is it really necessary?
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Oil Drainage: we need oil to get back to the pump pickup as quickly as possible, with the maximum amount of de-aeration possible.

I think as a general rule, any time we can avoid draining oil onto the crankshaft, oil control will be improved, cam in block engines typically drain oil from the cam, lifters, and rockers, back to the sump via holes in the lifter valley, which in turn drains the oil onto the crank, and aerates the hell out of it, which is where many OHC engines have a fairly big benefit compared to OHV engines, as they drain oil directly to the sump, instead of to the lifter valley, and onto the crank. I've seen SBC, and SBF engines install plugs or tubes in the valley drains so that the oil has to flow to the front or rear of the engine instead of down onto the crank, I see this as a possible drainage control win, but, care has to be taken to ensure enough oil drains back to the sump to keep the pump pickup covered.

another way to possibly improve oil drainage, is to paint or polish the areas where oil collects, so that the oil drains faster. an "old school" practice was to paint lifter valleys with "Gyptal", an electric motor winding paint, modern oil shedding coatings may offer a greater advantage.


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Windage: I feel this is a good point to define a term, what is windage?

Dictionary.com defines windage, in relation to machinery as

friction between a rotor and the air within its casing, as in an electric generator.

depending on who you ask, this particular definition could be contested, but I feel it's accurate enough for us to continue as long as we understand the "air" in this case, can be more than just air, but also the oil raining down onto the crank and rods from the lifter valley.

so, how can we control windage? this in particular ties into controlling drainage, if the oil drains directly to the sump instead of onto the crank, the oil won't be atomized by the crankshaft, and therefore, be less entrained in the air, but that's not the only place oil can make it's way onto the crank, the oil can be moved by acceleration of the vehicle, and splashed into the crank from the sump as well. This is in part where a "windage tray" can be employed to keep the splashed oil off of the crankshaft.

Most of us have seen videos like this where a feather and a brick or a bowling ball are dropped in a vacuum, for those of use that haven't

https://youtu.be/E43-CfukEgs

how is that relevant? well, if there's less air, there's less to keep the oil in suspension, and therefore it will fall to the sump faster, it also means that at a lower pressure, less air bubbles will be present in the oil, and therefore, the volume of oil pumped will be of a higher mass of oil, than in a higher atmospheric pressure in the crankcase.

there's a few ways crankcase pressure can be lowered that I'm aware of:

-the PCV system, its one of the few emissions systems that I am a big fan of, long term benefits can actually be noted from it, but it is advisable to run an oil separator to keep oil out of the intake tract. it won't draw a perfect vacuum, but it also won't invert seals or anything silly like that.

-exhaust venturi crankcase evacuation systems. These systems use a tube connected into the exhaust of the engine, the high velocity of the exhaust gasses traveling past the tube cause an area of low pressure, which can then be connected to the crankcase, and draw a vacuum on the crankcase. I have no data as to how much pressure such a system can remove.

-A Vacuum pump, a belt driven pump can be employed to suck the air out of the crankcase, and then discharge that air to the surrounding atmosphere. care must be taken to ensure the vacuum depression inside the crankcase doesn't cause cavitation of the oil pump, or inversions of the oil seals.

another option for reducing windage, is a crankshaft scraper, the idea, is that a plate that tightly fits the contours of the crankshaft counterweights and the connecting rods comes very close to contacting the crankshaft, and as the crank, and passes, the oil is stripped from the crank, and drained to the sump, instead of being sprayed into the next counterweight or connecting rod.

.

Enough words for now, I've had a bunch of whiskey and practically written a term paper... Please, share your thoughts and ideas of how to improve oil control in a wet sump engine, and any data you have to back up your ideas! I'll follow up with some of the things I'm working on with my crappy V6.

[ericjon262]

today, with less whiskey.

oil aeration. I'm reading an MIT paper, the test engine was a Ford DOHC V6. I'll include cliff notes.

https://dspace.mit.edu/handle/1721.1/38713

the dominate factors the contribute to oil aeration:

engine speed
Temperature
engine design
oil level

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Engine speed.

The paper states that engine speed is a dominate factor, but for a reason I didn't expect. I expected engine speed to be a factor due to the parts are spinning, and colliding with the oil, BUT, the paper actually states something quite different, the paper states that "Residence time", the time the oil is in the sump, is longer at slower engine speeds, therefore, the oil has more time for air bubbles to remove themselves from the oil.
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Oil Level.

seems kinda like a no brainer here, too much oil, and you're in the crank, too little, and the sump gets sucked dry, the key is to strike a balance, enough oil to increase residence time, but not get into the crank.

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engine design.

Of all engine components, the oil pan, baffle, and windage tray influence oil aeration the
most

good to know I'm working in the right direction.

the paper specifically mentions that the design of the oil pan, baffle, and windage tray should be such to direct oil to the pump, and avoid "Funneling" which in this case is describing the depression of the surface of the oil down to the pump pickup.

the paper also specifies the the oil returns should be below the level in the sump to avoid the oil coming in contact with air, this seems to be the norm with OHC engines, and not so much with older OHV engines like my LX9

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Oil temperature.

According to the paper, and some of my own schooling, as temperature rises, dissolved gasses will tend to come out of solution as bubbles in the oil. in an independent test, aeration was observed to be decreased when oil temperature was increased from 20C-100C in an open container of oil being agitated. an open container with an agitator isn't representative of a running engine though, which the paper also addresses.

As the oil circulates through the engine its temperature increases causing dissolved air to become bubbles. Unlike the open container, however, there is no escape path for the air bubbles. The bubbles remain trapped in the oil and increase aeration. This was observed in a study by Yano and Yabumoto. At constant engine speeds of 3000, 4000, 5000, and 6000 rpm, as oil temperature increased oil aeration also increased

it is unclear whether the engine used a forced crankcase ventilation, or a passive crankcase ventilation.

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Oil pressure

I believe the paper mislabeled this paragraph, from what I am reading, this more appears to describe crankcase pressure, or sump pressure, because once the oil is in the oil gallery, it is no longer able to absorb more air, the text of the paper states that as pressure is reduced, air bubble size is increased, and as the bubble size goes up, as the bubble size goes up, they rise faster, and the residence time is more effective because air can be removed, this suggests that systems that reduce crankcase pressure improve oil control in two modes, improved drainage, and improved de-aeration.

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I found this graphic interesting, again, Ford DOHC V6, but I imagine similar results could be found on other engines, but I don't have data to support other engines. I'm imagining oil flow to the heads being oil flow to just the cam and lifters on a typical OHV engine.



this leads me to think that any oil relief from oil pump NEEDs to be below the level in the sump is it doesn't relieve back to the suction of the pump, if the oil being relieved isn't aerated, then it will displace the aerated oil raining down from the crank and rods because it is denser than the aerated oil. For my engine in particular, I'll have to investigate how the oil pump relieves pressure.


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oil pumps....

where is enough enough? at present, there are 3 principle oil pumps that I am aware of for a 60V6, a "standard volume", a "high" volume, and the DOHC pump. all three of these pumps fit any 60V6 prior to the VVT engines. going off of memory, the VVT pump from a flow standpoint really isn't better, however, the pump should have a smother discharge pressure across the RPM range compared to the earlier pumps because of the higher tooth count, and may have different characteristics from a cavitation resistance standpoint.

I don't think a higher volume pump is a benefit unless the oil viscosity is reduced, otherwise the oil is just flowing out of the pump bypass, and I would argue a high volume pump might actually be a detriment because of the increased flow reduces residence time, and therefore lowers the amount of time the oil had to de-aerate. the other possible concern with a high volume pump, is pumping the sump dry, and sending all of the oil to the valve covers before it can drain back to the sump and the pump pickup.

I do think it may be worthwhile to use a higher volume pump in conjunction with a accumulator like an accusump, the higher volume would allow for the accumulator to be more quickly recharged, and the accumulator would provide some protection in the event the pump suction becomes uncovered.

tonight's whiskey is setting in, and it's 3 am... I'll be back later.

[The Dark Side of Will]

Of course the biggest source of free oil in the crankcase is the bottom end itself as oil flows out around the sides of the main and rod bearings. Smokey Yunick did some work with a transparent oil pan and illumination inside the crankcase in order to visualize what windage looks like. The air entraining oil droplets ends up clinging to the crankshaft and staying "stuck" within the rotating volume of the crankshaft. This phenomenon is reduced significantly with a crank scraper.

Also, there are "deep sump" drag race oil pans. Their purpose is not to run more oil, but to move the same amount of oil further away from the crankshaft in order to reduce windage.

For both heat transfer and mechanical retention, satellites are put together with a good bit of epoxy. The mixing process entrains a lot of air in the epoxy. That prevents the epoxy from achieving full strength, so the technician de-aerates the epoxy by placing the mix cup on a platter connected to a vacuum pump, dropping a bell jar over the cup and then turning the pump on. As the air bubbles expand, the epoxy looks like the blob coming to life, or like oobleck on a vibe table for a couple of seconds, then "dies" as all the air finds its way out. The only real difference between epoxy and oil in this situation is viscosity.

Oil temperature is key to getting water out of the oil. The rate at which water boils out of engine oil is "orders of magnitude" faster when the oil is warmer than the boiling point of water at crankcase internal pressure. Thus in a normal wet sump, the oil has to get warmer than 100C in order to boil off entrained water.

Of course the best is always a dry sump, but that's difficult to fit into a Fiero and expensive to add to an existing engine design.

[ericjon262]

Of course the biggest source of free oil in the crankcase is the bottom end itself as oil flows out around the sides of the main and rod bearings. Smokey Yunick did some work with a transparent oil pan and illumination inside the crankcase in order to visualize what windage looks like. The air entraining oil droplets ends up clinging to the crankshaft and staying "stuck" within the rotating volume of the crankshaft. This phenomenon is reduced significantly with a crank scraper.

that would be a cool experiment to witness. Somehow, I hadn't yet posted that I was considering a crank scraper with my custom windage tray, for a moment, I was actually considering two, one forward, one rear, I'm not sure a second is really necessary though for two reasons, the minor reason, it would be a short distance from the leading scraper, and the major reason, I suspect the majority of the oil needing to be removed by the scraper is oil draining from the cam, lifters, and heads, not the high velocity oil being flung from the main and rod bearings.

Thoughts?

Also, there are "deep sump" drag race oil pans. Their purpose is not to run more oil, but to move the same amount of oil further away from the crankshaft in order to reduce windage.

I've seen a few tests of oil pans on engine masters, and it's always interesting to see a part frequently overlooked from a performance standpoint make a difference in power. one of the things mentioned in one of the tests, was that crankcase pressure trends down with a increase in crankcase volume, a concept I hadn't considered before, that said, crankcase pressure was not instrumented during the test, or if it was, numbers were not provided. I have enough I/O with the MS3 to install a map sensor in the crankcase, I might do a temp install just to see what's there.

For both heat transfer and mechanical retention, satellites are put together with a good bit of epoxy. The mixing process entrains a lot of air in the epoxy. That prevents the epoxy from achieving full strength, so the technician de-aerates the epoxy by placing the mix cup on a platter connected to a vacuum pump, dropping a bell jar over the cup and then turning the pump on. As the air bubbles expand, the epoxy looks like the blob coming to life, or like oobleck on a vibe table for a couple of seconds, then "dies" as all the air finds its way out. The only real difference between epoxy and oil in this situation is viscosity.

this is another thing I've been carefully looking into options for, vacuum in the crankcase can have multiple benefits,

less air, means less wind resistance for the crank, rods, and pistons to travel through.
less air also means, less wind resistance for the oil falling back to the sump to travel through.
less air also means, higher differential pressure across the pistons
and of coarse, de-aeration of the oil.

the one downside i could see to lowering crankcase pressure, is that the possibility of cavitating the oil pump increases, that said, if the oil is returning to the sump faster, the level of the oil in the sump will be higher, and improve inlet pressure to the pump and lower the probability of cavitation, additionally, is the oil is de-aerated, the possibility of gas bubbles leaving solution in the pump inlet are reduced.

Oil temperature is key to getting water out of the oil. The rate at which water boils out of engine oil is "orders of magnitude" faster when the oil is warmer than the boiling point of water at crankcase internal pressure. Thus in a normal wet sump, the oil has to get warmer than 100C in order to boil off entrained water.

what were we saying about lower crankcase pressure having benefits? of yeah, here's another, the boiling point of water lowers below ambient pressure, so any water in the oil will boil out faster, with a lower crankcase pressure.

I actually almost made a post in this thread yesterday with regards to crankcase evacuation/ventilation. the way I see it, we have 3 options

in the intake like factory for almost everything.
in the exhaust with slashcuts
or a vacuum pump.

I've love to install a vacuum pump, however, they're priced a bit outside what I want to spend. a lower cost option would be to retrofit a A.I.R. (smog) pump, most are vane type air pumps and can draw a vacuum on a crankcase, but the vanes in the pumps don't like oil, and typically don't last long in such an application.

That leaves slashcuts, or in the intake. I'd rather not use the intake, it tends to make a mess of valves and things, and I'd rather not use slashcuts for reasons I'm not 100% able to grasp... I just don't like them. I'll probably end up installing slashcuts, even though I don't want to.

Of course the best is always a dry sump, but that's difficult to fit into a Fiero and expensive to add to an existing engine design.

Right, and don't think I haven't considered it... unfortunately, there's just so much that has to be done to make it work, without even considering the simple stuff like mounting a pump and oil tank, we have to figure out where we want to scavenge from, and how we get to those points. if I'm going to the trouble of a dry sump, it probably won't be with a 60v6, and there would be a ton of trick stuff going on.

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oil pumps have been on my mind alot, and I think the best idea is to just leave a stock pump in, and run an accusump(planning on this either way)

[zok15]

Pretty standard practice in the Subaru world to shim the oil pump relief and up the oil pressure in the motor. These motors have teeny tiny main and rod bearings since the crank is so short, and the theory is a higher pressure oil cushion for the crank and rods to ride on is more resistant to knock events.

I also imagine the standard practices of cleaning up sharp radii in the oil passages probably helps flow more oil with less cavitation.

I imagine the LZ9 oil pump cavitates less by having more teeth, and I would be surprised if the oil pump did not flow more with the additional oil squirters and the VVT. The VVT I am not positive would require more oil flow, but I am sure the oil squirters would.

I also imagine that increasing oil capacity plays a large role in preventing aerated oil getting sucked into the pickup as there is more time for the oil to chill in the pan before getting sucked into the pickup. All the high performance german cars have crazy oil capacities.

Would an oil cooler do anything for removing air bubbles from the oil as there is more time for the oil to flow through the lines and then the cooler before making its way to the bearings? Is there any other device you could put post pump - pre bearings (like built into a sandwich adapter) that could be used for removing air bubbles in the oil?

I have plans to add an Accusump to my WRX due to the low oil capacity and tendency for oil to stay in the heads during long hard turns. I have actually considered making a custom oil pan that allows me to route the driver's side header primaries behind the oil pan instead of in front of it. This leaves a big unused area normally taken up by the drivers side primaries in front of the pan that could be used for additional capacity.

I think capacity more than anything else can improve oiling when combined with a good crank scraper (and would also allow oil level to be farther away from the crank)

I think engine operating temps are directly related to oil viscosity requirements. My friend's E39 540 has crazy high operating temps and the factory oil is 10W-60.

Allegedly gerotor type oil pumps shear thin the oil more than a gear pump, it is easy to imagine why.

A PCV system with a large enough twin catch can prevents the vast majority of oil from entering the intake while allowing max vacuum on the crankcase. Of course there is no vacuum on the crankcase during WOT, maybe a boost activated vacuum pump that takes over during a WOT event would be the best of both worlds. It would be useful to know how much vacuum an exhaust slash cut system can pull, because that could theoretically pull a good vacuum at WOT also.

[ericjon262]

Pretty standard practice in the Subaru world to shim the oil pump relief and up the oil pressure in the motor. These motors have teeny tiny main and rod bearings since the crank is so short, and the theory is a higher pressure oil cushion for the crank and rods to ride on is more resistant to knock events.

I've gone back and forth on shimming the relief, without changing bearing clearances, or anything else that would change the flow requirements of the system, you make a small increase in oil flow in the system, and increase the required power to drive the pump. some of the testing engine masters performed actually showed a power increase in back to back testing by swapping the oil pump for one that outputs a lower pressure, that said, I don't always agree with the 10 PSI/1000 RPM rule that everyone is quick to throw around for the exact reason you mention, smaller bearings will require more pressure under the same load to prevent metal to metal contact between the crank and the bearings, compared to larger bearings, and I would argue this goes for both bearing diameter, and width.

I would imagine RPM is also a more important factor for the rod bearings, as the oil for the rods travels through the rotating crankshaft, to get to them. on most engines, the oil flow is from the OD of the main bearing journal, toward the crank centerline, and then out to the rods. and the oil briefly has to flow counter to centrifugal force. eventually, oil is traveling away from the crank, and centrifugal force is aiding flow. some high performance engines have alternate oiling to get to the rods, by oiling through the nose or faces of the crank. because I can't do anything to change this factor on my engine(s) I won't concern myself with the details much further.

I also imagine the standard practices of cleaning up sharp radii in the oil passages probably helps flow more oil with less cavitation.

I'd like to take a second to give my definition of cavitation, this particular definition is used in Naval nuclear power training, and is typically used in describing cavitation in WATER, but overall the definition works here as well, as long as we understand that saturation pressure in this case isn't a concern with the oil vaporizing the oil, but the dissolved gasses coming out of solution decreasing the effective volumetric flowrate of the pump.

"Cavitation: the formation and subsequent collapse of vapor bubbles due to pressure falling below and then rising above saturation pressure."

because the dissolved gasses are coming out of solution, their volume in the pump cavity now takes up volume that should be oil, once those pockets collapse at the pump discharge, the oil pressure is reduced because the flow requirement hasn't changed, but the volume of oil has decreased.

There was an issue of Hot Rod magazine probably a decade or so ago where a guy built a 1000 hp NA 555" rat, one of the details shared about that build was that all of the oil passages were somehow gone through with a ball hone or some other implement to ensure there were no restrictions present in the passages. I believe the oil drains back to the sump are far more important to be deburred than the galleries, as the only thing bringing the oil back to the sump is gravity. Most PCV and vacuum systems (dry sump not included) will tend to pull oil away, as they typically suck on the valve covers, high above the oil sump. That being said, a vacuum system should be pulling on a well sealed crankcase, and therefore not have a significant amount of airflow, I would also argue that the lower pressure in the crankcase cause by these systems aids draining by reducing air resistance.

I imagine the LZ9 oil pump cavitates less by having more teeth, and I would be surprised if the oil pump did not flow more with the additional oil squirters and the VVT. The VVT I am not positive would require more oil flow, but I am sure the oil squirters would.

First, it's worth mentioning the LZ9 pump doesn't fit in the earlier engines without modifications to the oil pan (I have tried) I can't say whether the opposite is true or not, but based on the clearance issues the LZ9 pump had, I would suspect the earlier pumps would fit the later pans.

I have pictures, and actually calculated the flowrate of the LZ9 oil pump, it is slightly more than the earlier pumps (DOHC excluded), but not nearly as much as would be expected based on the size difference between the pumps. while the LZ9 pump has more teeth, the teeth are shallower, and shorter than the earlier pumps





the result is a flow rate only slightly larger than the earlier pumps, that said, the discharge flow of the pump should be at a higher frequency, and therefore have a smoother pressure curve compared to the earlier pump. it's also not impossible that the LZ9 pump may require less power to turn to move the same amount of oil.

because the teeth a smaller, the pressure oscillations at the pump inlet will also be smaller, which could lead to less cavitation, at the same pump speed, I suspect that the overall effect of the cavitation would be worse with smaller teeth compared to larger teeth, as the same amount of gas expansion takes up more trapped volume of the pump.

in systems using positive displacement pumps, flow is determined by the pump, pressure is determined by the system. the pump will move the same volume(relatively speaking) with every cycle, up until the pump cavitates, or the relief pressure is met.

I also imagine that increasing oil capacity plays a large role in preventing aerated oil getting sucked into the pickup as there is more time for the oil to chill in the pan before getting sucked into the pickup. All the high performance german cars have crazy oil capacities.

to a point, yes, but the oil must be maintained away from the crankshaft and other moving parts in the engine. this "time for the oil to chill" is called residence time. ideally, the increased capacity would come from the sump being deeper, unfortunately, packaging requirements tend to not permit this.

Would an oil cooler do anything for removing air bubbles from the oil as there is more time for the oil to flow through the lines and then the cooler before making its way to the bearings? Is there any other device you could put post pump - pre bearings (like built into a sandwich adapter) that could be used for removing air bubbles in the oil?

a greater distance to the bearings would permit more time for any entrained air to be dissolved into the oil, but it cannot de-aerate the oil, as the gasses would have nowhere to go without relieving pressure. I don't see this as a benefit, as once the pressure is reduced, the air will come back out of solution. it would be more desirable to de-aerate in the sump where pressure is lower.

with water, the temperature relationship between de-aeration and temperature is non linear, but de-aeration does tend to increase with temperature, I imagine similar trends could be found with oil, obviously there's a point where hot oil is a detriment, regardless of whether it's 100% de-aerated though. dissolved gas, and entrained gasses probably should be considered separate problems, dissolved gasses in solution, from a lubrication standpoint are less of a problem than entrained gasses, however, from a oil life standpoint, entrained gases are probably less important. that said, reducing entrained gasses will also reduce dissolved gasses.

I have plans to add an Accusump to my WRX due to the low oil capacity and tendency for oil to stay in the heads during long hard turns. I have actually considered making a custom oil pan that allows me to route the driver's side header primaries behind the oil pan instead of in front of it. This leaves a big unused area normally taken up by the drivers side primaries in front of the pan that could be used for additional capacity.

I've been considering pan kickouts on my Fiero, however, I run into clearance issues with either the CV axles, or the starter, and I want to improve the ability to maintain the car as simple as possible, including corrective maintenance like changing starters.

I think capacity more than anything else can improve oiling when combined with a good crank scraper (and would also allow oil level to be farther away from the crank)

I think engine operating temps are directly related to oil viscosity requirements. My friend's E39 540 has crazy high operating temps and the factory oil is 10W-60.

oil temperature, and oil viscosity are inversely related, so I would tend to agree with your assessment. Sump capacity directly relates to residence time, which also leads to better oil de-aeration, and de-aerated oil has less volume than aerated oil, so it also contributes to keeping the same mass of oil further from the crank. all wins.

Allegedly gerotor type oil pumps shear thin the oil more than a gear pump, it is easy to imagine why.

based on the design of the two styles of pumps, I would imagine a gerotor pump is more efficient than a gear pump, I also base this assessment on the fact that I don't see gear pumps anymore on engines. if there was a drop in gerotor pump for my engine, I'd be interested in trying it, or at least running a few tests to see if one pump requires more power than the other at the same pressure.

A PCV system with a large enough twin catch can prevents the vast majority of oil from entering the intake while allowing max vacuum on the crankcase. Of course there is no vacuum on the crankcase during WOT, maybe a boost activated vacuum pump that takes over during a WOT event would be the best of both worlds. It would be useful to know how much vacuum an exhaust slash cut system can pull, because that could theoretically pull a good vacuum at WOT also.

at one point, I had a slashcut installed in my exhaust, but i never did get it completely installed on the car for a few reasons, one of which being that exhaust was replaced. at idle, you could feel it pulling a small amount of air if you put your hand on it, and performance would only be improved with higher mass flowrates of exhaust until the rest of the exhaust became a restriction and backpressure begins rising, in the case of my exhaust, I don't think backpressure could get to that point. I think any method of crankcase ventilation, or vacuum should include at least a single catch can, and ideally, a means to return collected oil to the sump.

Hopefully today I can manage to get some of my new windage tray started.


======================================

While 60V6 parts have been frequently mentioned in this thread, this thread is not necessarily be specific to them, the discussion is open to any engine

older publications related to gen 1 small block chevy's suggested cutting small grooves into the bottom plates of the oil pump to provide a relief path for oil trapped between the gear teeth as they mesh,



I considered making a similar modification to my oil pump, but I noticed in the above pictured oil pump gear pictures that the tips of the oil pump gear teeth are clipped, I suspect this was a less expensive way that GM could accomplish a similar effect. since I have a couple of pumps on the shelf, and a couple of bearing caps they could be bolted to, I may try a couple of experiments to see if it makes any difference.

[zok15]

While I see that the teeth are not deeper on the LZ9 oil pump, isn't the larger diameter of the gears/more teeth of the same size going to create a higher velocity of the oil at the same RPM? It does not seem like the reduced height of the gears compared to LX9 is enough to make up for this change in diameter.

I do not know if the gerotor design is necessarily better as much as it is much simpler, no intermediate shaft off the cam required which is carried forwards from distributor tech that no longer exists.

Makes sense that you would want de-aeration to occur prior to entering the pickup and would not be possible through a cooler or flow straightener. I guess cleaning up the oil passages is more for laminar flow and reducing restriction, a sharp edged hole cannot flow the same amount as a tube of the same diameter. I guess I imagined oil hitting those sharp edges in the oil passages and creating vortices would form larger bubbles if some air was present.

You may be able to gain a little volume on the pan under the crank snout, I am using this area for my mount/exhaust, but I do not believe you are.

I don't think shimming the relief would ever hurt oiling, especially with high RPM and getting oil to the rods as you mentioned overcoming the centripetal forces. I only think it may rob you of a little power. You can drill new oiling passages through the crank, I have seen it done, but that sounds difficult and hard to test.

I have also seen drilling a shallow depression on the side faces (top and bottom in our case) of the oil pump gears, gerotor or not, usually one per tooth, just to provide a pocket of oil for the gear to spin smoothly on relative to the pump housing.

I would be very interested in seeing a vacuum measurement of the slashcuts in the exhaust at WOT, being NA it is not something I need in the Fiero, but have been curious about for the Subie as the PCV system in those is meh and they are super sensitive to knock. Also the down pipe is right next to where the PCV outlet is on the crankcase so it would be very easy to implement.

[ericjon262]

the teeth on the LZ9 pump are shallower as well, it may not look like it in the pictures, I did measure them, although I don't have the measurements handy anymore. my conclusion was that the pump would not flow a significant amount more than the stock pump.

I suspect shimming the relief would mostly only affect oil pressure at elevated RPM, when the relief is bypassing oil, although I don't have anything to back that up, any time you increase the pump's outlet pressure, you are also going to increase the drive power requirement, which will cause a power loss, along with increased stress on the pump body, the gears driving the pump, and in the case of a 60v6, the timing set, and if the increased pressure is more than you need, it's only reducing residence time, and limiting the de-aeration of the oil. IMO, from a bearing reliability standpoint, that's not worth it. now, there's a secondary function of the oiling system that hasn't been discussed, and that's valvetrain hydraulics, if the valvetrain hydraulics need more oil pressure, then shimming the pump may be worth something.

at present, my oil pan is part of my front engine mount, I'm not sure I want to change that yet. for now, I would prefer to maintain the stock oil pan geometry, and focus on a windage tray, baffles, a crank scraper, and reducing crankcase pressure to improve oil control.

[zok15]

Well it looks like oil pressure hits full pressure at about 3000 rpms. The OEMs probably have designed this to be optimized where the engine will most likely live in an average use case. I can imagine that bumping the oil pressure will help a motor that is designed to live at higher RPMs and definitely one with much higher cylinder pressures pushing that much more force into the crank. And like I said, with the Subarus it is mainly for preventing bearing contact during knock events, but a boxer crank is extra sensitive to these things due to the motor layout.

[ericjon262]

for what it's worth, I log oil pressure with my MS3, I don't see a point where oil pressure levels off, suggesting that the relief isn't open up to 6500 RPM or so, the pump is at about 80 PSI at that point.

[zok15]

And I assume your pressure sender is post relief?

[ericjon262]

you pretty much don't have a choice but to measure it after the relief, the pump relief is the cylindrical bump my thumb is pointing at.



I'm fairly certain it relives back to the pump suction, but I haven't taken it far enough apart to find out.


Cross posting this from my build thread, because it's relevant.

I made some basic progress on the windage tray, this plate is intended to be the foundation for the windage tray, and the crank scraper



some notes. in the pre prototype phases, I noticed the one of the main studs near the oil pump wouldn't have enough room to mount the tray under without significant modification to the pump,



So the offending interference was omitted and the hanging ledge will be reinforced so that it doesn't move. (green circle) the initial prototype, didn't quite fit perfect, mainly, the rods didn't have enough clearance in the red circled areas. the yellow circles highlight relief cuts, which will make it easier to bend those tabs towards the crankshaft about 45 degrees, this angled portion will serve as the mount for the crank scraper.

The blue arrows represent the other PITA that I'll have to carefully work around, the main caps on the 60V6 bolt to the oil pan, and therefore, the oil pan is narrower in those areas. currently, the overall width of the tray foundation is narrower than the main caps, so there will be clearance between the pan and the scraper/tray, although I have yet to measure how much.



the crank scraper will be on the front side of the engine, and should aid in collecting the vast majority of the drainage from the top end, as well as provide for a baffle to block the turbo oil drain from getting onto the crank, although I don't think it would ever make its way up there,

here's a crappy paint drawing of what I'm slowly working towards. the light blue is the turbo oil drain, the red, the crank scraper, the green, the windage tray, and the purple is a baffle that I might add. if I add the baffle, it will be perforated, as well as angled towards the oil pump pickup, since the sump is short front to back, this baffle should help prevent oil from flowing up the rear wall of the sump, and towards the crankshaft, under hard acceleration. but still allow for oil to drain back to the sump. I wouldn't mind adding a second crank scraper on the rear side of the engine, but unfortunately, there's almost no way to package that.

[ericjon262]

I was considering my crank scraper placement, and came to a realization. With the scraper on the forward part of the oil pan/crank, and angled in the manner it is, oil would build up on that edge, and under hard acceleration, be somewhat captured by the scraper and the crank, reducing residence time in the sump.

I see two options, in the graphics, the orange blobs represent oil being removed from the crankshaft.

one is to make the scraper near vertical, and overall, shorter. this way, the oil can't accumulate on the scraper, and under accelleration, it's forced onto the scraper, not up into the path of the crankshaft



option 2, is to place the scraper downstream, upstroke side of the crank. on the one hand, this will allow the acceleration of the vehicle to aid in the stripping of the crank, on the other hand, the oil is held against the crank for a longer period, and not returned to the sump, and therefore have less residence time, and less time to de-aerate.



of coarse, there's the third option, of running two scrappers, a leading and a trailing, which I may end up doing.

I haven't made any real progress on the actual windage tray portion of the sump yet, but I am planning on using some PTFE coated expanded metal screen material from Stef's

https://www.summitracing.com/parts/stf-9805

if I run a trailing crank scraper, I'll add holes in the screen for the oil to drain down from the scraper to the sump

I'd love opinions on baffling the sump. From the factory, GM provided very little baffling, but also from the factory, the cars these engines were in did not accelerate as hard, or turn as hard as I hope this car will, that said, baffles can reduce the effective volume of the crankcase, therefore raising crankcase pressure, increasing the importance of a PCV or vacuum system.

I might reach out to some of the pump manufacturers and see if they can provide more data on the pumps, specifically, required inlet pressure, and flowrates, and relief settings. I've been giving more thorough consideration to pump size and relief settings for my engine specifically because of the hydraulic lifters, Higher pressure should result in less lifter bleed down, and a more stable valvetrain, especially with tough valvesprings and boost, or is my logic flawed?

[zok15]

Could you just go pic 1 second graphic with short and vertical but build it into the windage tray (green) so on acceleration it will follow the bottom curve away from the crank? Probably has the most de-aeration potential as well doing it this way, as it will film and drip with maximum accumulation without a sharp edge as the lowest point.

[ericjon262]

I think a shear edge that drops the oil to the sump is better, because then the oil is available for the pump to supply to the bearings, I would prefer aerated oil to no oil, what do you think?

I'm currently working towards running two scrapers, like so:



however, I'm still running into clearance issues, and if I can avoid it, I'd rather not further modify the pan, so I may need to make more adjustments.





I've been trying to research and read as much as possible about oil control, something that hasn't been discussed yet in detail in this thread, is oil flow. Reading another thread suggested restricting oil flow to the cam bearings, which would provide a bias towards oil flowing to the main and rod bearings, which are spinning faster, and under higher load. That also leads to another point, that the best oil drainage/windage control, can't make up for a poorly assembled engine with incorrect clearances. While I have no intention of removing the cam bearings, and reinstalling them with restricted feeds, I'd still be interested in hearing thoughts on it. My thoughts are that the cam spins at half the speed, and I would argue has less load at any point than the mains or rods, but I also haven't performed any load calculations for the exhaust valves opening against cylinder pressure. I think if I were to consider restricting oil to the cam bearings, I would consider putting wider bearings in, or roller cam bearings (lol, no.).

[Shaun41178(2)]

Here is my opinion but you won't like it.

Ditch the idea of a windage tray and or crank scraper. At the end of the day it's a lx9 engine from gm. It's not a formula 1 engine. Not having a crank scraper isn't gonna give you a noticeable loss in power nor is it gonna do anything measurable for oil in your pan.

You have a streetcar with a street engine.

If I was building an lz engine, and I used arp studs for the mains, and I couldn't use the factory windage tray, I wouldn't care. I wouldn't waste hours of my time and materials costs to figure it out either. To me it's not worth the hassle.

Spend your time elsewhere in the build. I mean seriously, how much time have you dedicated already, and how much more do you think you have to commit, to figure out a solution?

Get the thing in and running and enjoy it. It's been 12 years for your build dude!

[ericjon262]

Here is my opinion but you won't like it.

Ditch the idea of a windage tray and or crank scraper. At the end of the day it's a lx9 engine from gm. It's not a formula 1 engine. Not having a crank scraper isn't gonna give you a noticeable loss in power nor is it gonna do anything measurable for oil in your pan.

You have a streetcar with a street engine.

If I was building an lz engine, and I used arp studs for the mains, and I couldn't use the factory windage tray, I wouldn't care. I wouldn't waste hours of my time and materials costs to figure it out either. To me it's not worth the hassle.

Spend your time elsewhere in the build. I mean seriously, how much time have you dedicated already, and how much more do you think you have to commit, to figure out a solution?

Get the thing in and running and enjoy it. It's been 12 years for your build dude!

FWIW, there have been several real world dyno tests on engines with solid roller lifters, that have shown measurable power gains with just oil system modifications, and I imagine any benefit seen on a solid roller would only be emphasized on a hydraulic roller due to the nature of the hydraulic lifter using oil. there's also the secondary consideration of reliability under more consistent oil pressure/flow.

I know you're not wrong when you say it will run without it, it's fairly obvious by the fact that plenty of cars haven't had windage trays or crank scrapers from the factory. I guess the only downside I see from attempting to optimize oil control, is it takes a little research, time and effort.

The car is running, and I'm currently enjoying it, I have a minimal amount of time invested at this point, and I also don't have a cam or headgaskets for it either way, so I might as well make it better than it currently is until I do, especially because I have the material to do it already. I also enjoy the journey making it better, and making improvements.

[ericjon262]

I really wanted to make the dual scrapers work, but the more I tried, the more they fought, and upon closer inspection, the leading scraper wouldn't be very effective due to it extending at a tangent angle to the crank, and not radially, the trailing scraper. even though the leading scraper would be more effective for oil control, it's reduced effectiveness due to it's angle, and packaging challenges have lead me to go ahead and decide to omit it.

In the meantime, I began trimming the windage screen, the material is pretty simple, and neat. hold it one way, and you can easily see through it, hold it the other, and it's quite obscured.

kinda hard to tell in the pictures, but it's still cool stuff.





here's a shot of the initial trimming of the screen



I'll need to trim it to fit in the oil pan, the areas where the pan bolts to the main caps will interfere, as the walls of the pan are angled towards the main cap. I intend to cut back the screen near the scraper, to provide an area for the oil to drain off of the scraper.

I'll probably also trim back the front edge of the screen to allow oil draining down the front of the block to go straight to the pan instead of on top of the tray, obviously it still needs a ton of trimming just to fit, but the general shape is correct.



one of the details I still need to address is the dipstick, I'll need to put a hole in the screen to allow the tube to pass through, not a big deal, but I don't want to do it until the screen is permanently attached to the engine so the location is spot on.

[ericjon262]

we're on the 3rd iteration of the scraper/windage tray mount, since the leading scraper was removed, I decided to add tabs to secure the screen to the base, along with a tab off of the rear main bearing cap. the tabs will be bent up towards the main bearing caps.



installed on the engine, prior to bending, it fits pretty good considering my measurements weren't hyper accurate. as dumb as it sounds, I don't plan on that being the actual scraper, I plan to pick up a thinner piece of polished stainless for the job, and carefully trimming it to fit the crank. then mounting it to the parts seen here.



after bending, some clearance was required so the scraper wouldn't hit the crank.



some minor details, this tab is a little too far from the screen, I'll need to make a new one about 15mm longer.



the front side of the windage also hits the oil pan, I made it slightly too long, in this case, I'll just trim it until the oil pan fits. the screen will be mounted to the scraper by the coupling nuts visible in the pictures, however, I only had 4, so I'll have to pick up at least two more, along with hardware to mount the screen over the front edge. I also made the decision that I'm going to go ahead and cut the screen so that it ends at the edges of the main caps, at the mounting tabs, which should provide a drain path for any oil thrown off of the crankshaft between the side of the oil pan, and the screen, instead of trapping it between the crank and the screen.

[zok15]

I think a shear edge that drops the oil to the sump is better, because then the oil is available for the pump to supply to the bearings, I would prefer aerated oil to no oil, what do you think?

I think it will be negligible either way really, I don't think my solution would really have better de-aeration, and I think the return to the pan one way vs the other will be pretty negligible as well. I think removing oil from the crank will be good regardless.

I do think you should try and get some extra pan volume though, I think that's worth it IMO and I think that will do more to help with oiling than anything else, and I am sure you can find space.