Oil's affect on motorcycle gear shift feel?

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Originally Posted By: bulwnkl
Originally Posted By: Shannow
Agree wholeheartedly that for the same pressure (i.e. sitting on relief), thinner oil sends more through the squirters.


I knew you'd realize this reality eventually. ;-)


If only people would realise that the other side of the coin of it is lower pressure lower flow, but we're getting there I hope.
 
Originally Posted By: Shannow
Originally Posted By: bulwnkl
Originally Posted By: Shannow
Agree wholeheartedly that for the same pressure (i.e. sitting on relief), thinner oil sends more through the squirters.


I knew you'd realize this reality eventually. ;-)


If only people would realise that the other side of the coin of it is lower pressure lower flow, but we're getting there I hope.


Not necessarily true for a positive displacement oil pump fed system if the pump is not in pressure relief.
 
Originally Posted By: ZeeOSix
Originally Posted By: Shannow
Originally Posted By: bulwnkl
Originally Posted By: Shannow
Agree wholeheartedly that for the same pressure (i.e. sitting on relief), thinner oil sends more through the squirters.


I knew you'd realize this reality eventually. ;-)


If only people would realise that the other side of the coin of it is lower pressure lower flow, but we're getting there I hope.


Not necessarily true for a positive displacement oil pump fed system if the pump is not in pressure relief.


THROUGH THE SQUIRTERS...AT SAME PRESSURE...
 
Yes, I agree with said above, but with some important caveats, and that is you will only get more flow volume with less viscous oil under the one condition of the oil pump being at pump pressure relief. BUT, if the oil pump is not in pressure relief, then you get the same flow volume regardless of oil viscosity. That's the nature of a positive displacement oiling system, and that's what my comment above was about - I qualified the comment with "if the pump is not in pressure relief".

The flow going through any restrictive element in an engine is dependent on what specific fixed flow resistance that element comprises of the over all flow resistance of the oiling system. A more restrictive element will get less flow compared to a less restrictive element - even with the PD oil pump not in pressure relief. The PD oil pump puts out X volume at Y RPM, and that X volume is split between all flow paths within the engine based on each path's fixed flow resistance. The flow volume split percentages of each element doesn't change because each element's flow resistance is fixed.

In other words, if the oil squirters flowed 10% of the total oil volume going into the engine from the positive displacement oil pump, then they will always flow 10% of the total flow regardless of the supply pressure & volume as long as the PD oil pump is not in pressure relief.

In the rare case where the oil pump is in pressure relief, if oil A was more viscous than oil B, then the whole engine will be getting more oil volume going through it with oil A, and each restrictive element path will also be getting more oil flow volume compared to the pump being in pressure relief with the less viscous oil B.
 
Originally Posted By: ZeeOSix
Yes, I agree with said above, but with some important caveats, and that is you will only get more flow volume with less viscous oil under the one condition of the oil pump being at pump pressure relief. BUT, if the oil pump is not in pressure relief, then you get the same flow volume regardless of oil viscosity. That's the nature of a positive displacement oiling system, and that's what my comment above was about - I qualified the comment with "if the pump is not in pressure relief".

The flow going through any restrictive element in an engine is dependent on what specific fixed flow resistance that element comprises of the over all flow resistance of the oiling system. A more restrictive element will get less flow compared to a less restrictive element - even with the PD oil pump not in pressure relief. The PD oil pump puts out X volume at Y RPM, and that X volume is split between all flow paths within the engine based on each path's fixed flow resistance. The flow volume split percentages of each element doesn't change because each element's flow resistance is fixed.

In other words, if the oil squirters flowed 10% of the total oil volume going into the engine from the positive displacement oil pump, then they will always flow 10% of the total flow regardless of the supply pressure & volume as long as the PD oil pump is not in pressure relief.

In the rare case where the oil pump is in pressure relief, if oil A was more viscous than oil B, then the whole engine will be getting more oil volume going through it with oil A, and each restrictive element path will also be getting more oil flow volume compared to the pump being in pressure relief with the less viscous oil B.


Problem with your argument is that you are considering an engine to be a number of restrictive elements in parallel, they are not.

The oil pump supplies oil to the galleries, and the bearings draw the oil from the galleries...only sufficient to replace the side leakage from the bearings.

If the pump supplies more volume (which it invariably will), you build oil pressure.

At low revs, the leakage is more closely related to the KV, at high revs, the HTHS is the predominant factor.

The squirters have a flow versus sqrt of guage pressure difference, and will deliver oil based on the pressure supplied to them.

If a higher viscosity oil is used, the gallery pressure will increase as the bearing shave less need of make-up, oil pressure will go up some, and the squirters will flow MORE oil, as the gallery pressure is increased.

It's not a linear percentage relationship between resistive elements in a circuit.
 
What I said is basically true ... you're splitting hairs with mumble jumble. Once the engine's whole oiling system is "engulfed" and flowing oil, there isn't going to be any huge changes going on with respect to the percentage split of flow through each element of the engine.

Originally Posted By: Shannow

The squirters have a flow versus sqrt of guage pressure difference, and will deliver oil based on the pressure supplied to them.


That's pretty much true for any flow restrictive component in the oiling system when the system is pressure fed. But when the system is volume fed (and the result is a seen pressure) then the volume coming out of the pump is split up based on each elements restriction. The only time the system is pressure fed dependent is when the pump is in pressure relief. The oil galleries in the engine are like giant oil supply lines relative to the restrictive flow elements.
 
Originally Posted By: ZeeOSix
What I said is basically true ... you're splitting hairs with mumble jumble.


Thanks...the willful ignorance on this site is annoying.

Enjoy your bliss...
 
^^^ LoL ... yeah, you too. You seem to think oil squirters have some kind of special "flow physics" of their own. They really don't. They have a fixed specific resistance to flow (based on their exact design) like any other flow component in an oiling system, and flow a split of the total volume supplied to the engine based on their fixed resistance. That flow spit percentage basically stays constant, regardless of the oil volume or viscosity supplied by the PD pump.

I doubt the flow split percentage changes enough in all the elements comprising the oiling system to even matter or could even be measured. You have a reference white paper where it was proven that the flow spit is changing dramatically under different engine PRM (ie, varying oil pump volume/pressure outputs)?
 
Originally Posted By: ZeeOSix
^^^ LoL ... yeah, you too. You seem to think oil squirters have some kind of special "flow physics" of their own. They really don't. They have a fixed specific resistance to flow (based on their exact design) like any other flow component in an oiling system, and flow a split of the total volume supplied to the engine based on their fixed resistance. That flow spit percentage basically stays constant, regardless of the oil volume or viscosity supplied by the PD pump.


OK then...bait taken, gear up with some data to prove it...

Do you understand hydrodynamic lubrication ?

Do you understand Bernoulli's equation ?

Do you understand how viscosity affect the application of Bernoulli ?

And I ask you exactly HOW a designer could design a system without sophisticated hydraulic valving that apportions the same percentage flow to each area ?

Even the speed ratio between cams and bearings changes the flow ratios between them.

Oil squirters obey normal physics...I've never offered anything else...bearings obey normal physics, which is all I've ever said...they don't behave the same or linear, and the parallel paths are NOT of equal resistance to flow.

But if you posit that the ratios are fixed, have at it, and provide something that supports it...or are you all posit and no evidence like a few others ?

By stating that I'm applying some sort of "special" physics, you are indicating that you have a "feeling" on how stuff works, but don't have ANY actual grounding in any of the above subjects.

But you can convince me, with data...if you've got it.
 
Originally Posted By: Shannow
But you can convince me, with data...if you've got it.


I'll say the same thing to you. Based on your belief, what would you say is the total change in flow volume split percentage of an oil squinter over the entire PRM range of an engine from idle to redline? Is it 1%, 10%, 15% ... ?
 
Originally Posted By: Shannow

And I ask you exactly HOW a designer could design a system without sophisticated hydraulic valving that apportions the same percentage flow to each area ?


I never said each flow element of the engine has the same percentage of flow split. I said the percentage split of each component (whatever that may be) basically stays constant.

I believe you when you say certain types of bearings may have a non-linear flow volume as RPM changes, but in reality how much of a change does it really have that would make any difference in the real world?
 
Originally Posted By: ZeeOSix
Originally Posted By: Shannow
But you can convince me, with data...if you've got it.


I'll say the same thing to you. Based on your belief, what would you say is the total change in flow volume of an oil squinter over the entire PRM range of an engine from idle to redline? Is it 1%, 15%, 40% ... ?


I told you, squirter oil flow is based on pressure applied to it, not RPM...asking for an answer to a nonsensical question ?

But here's how much oil a bearing draws...

sommerfeld%20side%20flow.jpg


Pick an L/D ratio (that's length to diameter, make it 1/4 because that's close to engine bearings....make viscosity, make clearance (c), Radius (r), and load (P) and viscosity (u) constant, and change RPM...upwards, and you can see that the normalised flow drops with RPM...

The bearings require less oil, draw less oil from the galleries to make up for side leakage...in bug turbine bearings, they will draw a couple of psi vacuum to attain that make-up flow.

So bearings, all things being equal draw off less normalised flow as RPM increases.

PD pumps provide a linear volume RPM relationship.

So providing a linear flow availability (PD pump) to a reduced requirement for make-up (the bearings) creates more backpressure with increasing RPM, which you read as oil pressure...

Simple, isn't it ?

As can be (very) simply deduced, looking at the slopes of the curves, a cam turning at half speed has a different change in flow characteristic as the mains.

The squirters, obeying regular laws of physics, flow more with this increasing pressure, and the ratio of squirter flow to bearing flow therefore increases...the percentages change, and are not fixed.

Again, asking a nonsensical question (% change in squirter flow versus RPM) in and of itself clearly identifies that you really haven't had the opportunity to grasp fluid dynamics...

Is your position based on science or belief ?

By asking the proverbial nonsensical question, I'd posit that you lean towards the latter.

(and science has proven that when your beliefs stop working, the centres in your brain that respond to pain light up, and you reject it).
 
Originally Posted By: ZeeOSix
I never said each flow element of the engine has the same percentage of flow split. I said the percentage split of each component (whatever that may be) basically stays constant.


???

Now you are confusing me...you "never said that they were the same", "but that they are the same"...
 
Originally Posted By: Shannow

I told you, squirter oil flow is based on pressure applied to it, not RPM...asking for an answer to a nonsensical question ?


Well, actually more engine RPM means more volume being forced through the squirter (or any other flow element), and the resulting pressure is seen. So yes, in the case of an engine with a PD oil pump the flow through it (and everything else) IS a product of RPM which produced the oil pump volume.

Originally Posted By: Shannow
Again, asking a nonsensical question (% change in squirter flow versus RPM) in and of itself clearly identifies that you really haven't had the opportunity to grasp fluid dynamics.


I don't think you're really grasping my question. I'll try again. You say that as engine RPM increases the tight crank, rod and cam bearings will flow less oil (non-linear flow curve with increased oil volume supplied) and the result is that the oil squirters will then flow more oil as a result (ie, the flow slit percentage to the squirters will increase). Isn't that what you are saying?

So let's say the oil squirters at idle flow 10% of the total flow volume from the pump. As you increase engine RPM the flow volume (and resulting oil pressure) will increase. At 2000 RPM are the oil squirters now drawing 11%, 15%, 20% of the total volume? At 5000 RPM they would be drawing an even higher percentage ... by how much? Does it change enough to even be measurable? I doubt it changes enough to even matter as engines can run for hours on end at near redline in race conditions and never fail.

I just want to know what oil will make my XSR shift less notchy while down shifting.
whistle.gif
 
Originally Posted By: Shannow
Originally Posted By: ZeeOSix
I never said each flow element of the engine has the same percentage of flow split. I said the percentage split of each component (whatever that may be) basically stays constant.


???

Now you are confusing me...you "never said that they were the same", "but that they are the same"...


Go back and do some re-reading. You thought that I said the flow split was the same percentage between engine components. I said the flow spit percentage of each component (whatever that may be) basically stayed the same through the oiling system's flow range, not that they all had the same exact same flow split percentage.
 
Originally Posted By: ZeeOSix
I just want to know what oil will make my XSR shift less notchy while down shifting.
whistle.gif




Go back to where it started...M1 AFE0W30 is good for you clutch, and flows more, and has less (in use) HTHS than the Japanese OEM's recommendation against gear pitting...which is really gear fork failure...and it flows more, because you need the relief closed.

That's all about shift feel ?
 
And that gentlemen is why brand X shifts better than brand Y.
I really do enjoy the read and glean as much as I can from it. I've been riding and racing since 1958 and have so enjoyed the progress in lubricants and tire technology.
Keep going, I'm learning, just don't know how much yet.

Smoky
 
Originally Posted By: turtlevette

I was being kind before. I doubt a real man would be caught dead on something that revs to 20,000 rpm. Sounds like a Cox 2 stroke in a model plane.



How about a 1000cc 4 cylinder that is rev-limited to approx. 18k rpm, (they can rev higher, but are restricted because teams are only allowed so many engines per season) makes 240 HP in this restricted form, in a bike weighing 350 lbs. The bikes are reaching nearly 220 mph at the end of the Mugello front straight. They could easily go faster with more room to run and appropriate gearing.

Suffice it to say there are very few "real men" that have the skill and intestinal fortitude to ride these bikes to their potential..
 
Originally Posted By: ZeeOSix

Go back and do some re-reading. You thought that I said the flow split was theory same percentage between engine components. I said the flow spit percentage of each component (whatever that may be) basically stayed the same through the oiling system's flow range, not that they all had the same exact same flow split percentage.


Let's settle it this way. Neither of your statements are true.

You have a fluids background? Doing what?
 
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