aliveagain
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posted January 03, 2005 09:46 PM
oil relief valve
I was wondering why they would even have an internal oil relief valve when I pulled the oil pan.When does it open and for how long?I wonder because if it's at high rpm's,then would putting a heavier spring give us more flow and or pressure at speed reducing a chance of bearing failure?
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spencercyclecom
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posted January 03, 2005 11:05 PM
 Edited By: spencercyclecom on 3 Jan 2005 23:30
install a washer/shim for more pressure.
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entropy
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posted January 04, 2005 03:33 AM
Edited By: entropy on 5 Jan 2005 13:04
That JohnnyCheese sure likes to measure stuff, 
On latest build:
JC measured my pressure relief valve opening pressure = 60#,
he then shimmed it 1.6mm, remeasured opening pressure = 80#.
(note: i asked for the shimming cause i "heard" it was beneficial)
However, the engine oil pressure when motor is thoroughly warmed up (heatsoaked) was 22#@4000rpm (right on OEM spec), about 45# at max rpm on dyno. My oil pump is perfect.
Soooooo, what difference does shimming the relief valve make if (when hot) the pressure never gets to even 60#??????? Maybe for that 1st pass off the trailer???
when barely warmed up, i can easily rev it and make the oil pressure guage go to 80#, but not when it is hot.
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Ra12r
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posted January 04, 2005 06:13 AM
[Quote] Soooooo, what difference does......................
That question can be ask about MANY MODS or PRODUCTS that are available!
So many things here, just sound good, on the net and have absolutely no effect in the real world. But if the right name post the information, then the idea or product is law.........
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entropy
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posted January 04, 2005 06:51 AM
i am sure there is a good reason for shimming the relief valve (hell, we did it!), I just don't know what it is????
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entropy
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posted January 04, 2005 06:52 AM
ra,
how come yr not going to MIR on Jun 10???
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Johnnycheese
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posted January 04, 2005 01:01 PM
quote:
i am sure there is a good reason for shimming the relief valve (hell, we did it!), I just don't know what it is????
so my dyno won't blow up your motor
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entropy
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posted January 04, 2005 01:25 PM
quote:
quote:
i am sure there is a good reason for shimming the relief valve (hell, we did it!), I just don't know what it is????
so my dyno won't blow up your motor
laff my fukken ass off!!!!!
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ZXLNT
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posted January 04, 2005 11:03 PM
Lol....
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Ra12r
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posted January 05, 2005 06:11 AM
Not going to MIR because I will be in Myrtle Beach for BBW. If it was at the Rock then I would due to driving time. I have put it on the calender, but as of right now it doesn't look like I will be able you deliver you'all a good "lesson"......... smile
Just for the record, I have my valve shimmed too........... But, why after seeing your measured pressure results......
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canadamaxxer
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posted January 05, 2005 12:24 PM
Edited By: canadamaxxer on 5 Jan 2005 12:26
That valve only works to limit the maximum pressure put out by the pump PROVIDING the pump has sufficient volume to achieve that pressure. It is just a blow off valve. Obviously Entropy's bearing clearances are correct (they are the orifaces that regulate the pressure, it it not the pump that does that), so the next step to raise pressure is to install a higher volume pump (if available) to overcome the pressure loss through the orifaces (the bearing-to-journal clearances). The real question has to be: what is the minimum pressure needed to allow the engine to survive (or thrive) and therefore how much pressure do these engines really need? I know that for years GM spec for the small block has been a mimimum of 5 PSI at idle. That is not optimum, but the stock engine will survive indefinitely at that pressure. There is a question of diminished returns (cost to increase the pressure vs the actual gain) and also a question of desirability of increasing the pressure bejond a certain point (I have heard of erosion on bearing shells as a result of excessive pressure).
To have that blow-off valve control pressure in the pump is a bad thing.... especially when the spring work hardens from constant flexing and breaks....causing a virtual total loss of pressure (I have seen it happen)......it is really only designed to prevent hydraulicing of the pump during cold startup (imagine starting your engine at -40 and having the pumps gears or vanes churning through that molasses....and then having nowhere for the stuff to flow because it is too thick to flow through the oil journals) or because of an obstruction (think of a plugged oil filter). I have heard of oil pump drives shearing off because of that valve sticking or because the oil was even too thick to flow through the oriface created by the check ball, which created a hydraulic situation. Obviously this is not as big of a concern for bikes as cars (unless someone fires up their bike at -40), but the valve is still there in case of any kind of obstruction. Hydraulic force is amazingly powerful and will split cast iron or aluminium without missing a beat, which means there always has to be an escape route for the pressure. That same hydraulic force is also why we don't need 100's of psi of oil pressure (even on a dyno  )
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entropy
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posted January 06, 2005 01:31 AM
canadamaxxer,
thx for taking the time to tapping out that info; very helpful!
what do you do which has you knowing this stuff???
thanks again
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canadamaxxer
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posted January 06, 2005 07:00 AM
Entropy: I'm a licensed Automotive Mechanic. All of the principles are the same...and it is so helpful....
Glad I can contribute.....
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psycho1122
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posted January 06, 2005 07:37 AM
I believe in the saying " There's THINKING and then there's KNOWING"
I think it's GREAT we have people "In The KNOW"
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entropy
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posted January 06, 2005 10:18 AM
yep, i agree, knowing is good.
BUT, i still wonder why so many folks (including me), alot of them very knowledgable (not including me), shim the oil relief.
My guts tell me there has to be some good reason.
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canadamaxxer
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posted January 06, 2005 12:06 PM
Here is the skinny on the pressure relief valve: it is usually a ball bearing that is held against a seat by spring pressure. If the spring is calibrated to unseat at 60psi then the maximum pressure possible in the system is 60 psi. Increase the spring pressure and the ball unseats at a higher pressure. The sole typical benefit is cold starts where the oil may be thick enough inside the pump to unseat the ball at 60 psi, but is thin enough to flow if the seat pressure on the ball is raised to unseat it at 80 psi (as an example). If an oiling system (such as Entropy's) sits at 20 PSI at 4000 rpm and 45PSI wound right out, then the 80 psi blowoff pressure of the relief valve is NEVER an issue. It will not unseat until pressure exceeds the calibrated pressure.
Keep in mind that liquids are for all intents and purposes, non-compressible.
This is a very simple hydraulic circuit: pump, pressure relief valve, plumbing, orifaces. That's it. If the volume of the pump is sufficient to create pressure despite the loss as a result of the orifaces (having to do with clearance vs viscosity of the oil), then pressure is shown on a gauge. If the pressure relief valve is set to (as an example) 60 psi and there is sufficient pressure created by the pump to exceed that valves seat pressure (and the orifaces), the valve will open and bleed the excess pressure until equilibrium is reached again (60 psi).......UNLESS the volume of the pump exceeds the volume that the relief valve can flow.....which will cause the pressure to climb bejond the 60 psi despite the many leaks engineered into the system. This is VERY bad and could build pressure into the 100's or 1000's of PSI. This is why relief valves are designed to flow more than the pump can put out, but if excessive shimming is used (to increase seat pressure), the ball may not be able to move far enough to allow sufficient flow....and that's bad!!! Given the choice I would use a spring that had a greater seat pressure at the same compressed height than stock , rather than shims to increase the seat pressure (automatic transmissions are a tremendous source for high quality springs). It's the same concept as valves in a cylinder head. If you want stronger valve springs you could shim them up (which is wrong) or simply get stronger springs (which is correct).
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posted January 06, 2005 12:30 PM
So basically what yer sayin..is that shimmed oil relief valves blow up motors.
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ZXLNT
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posted January 06, 2005 12:35 PM
Only if ran on a dyno....
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canadamaxxer
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posted January 06, 2005 01:56 PM
I write all of the above info and all you can do is twist my words into that?????
quote:
So basically what yer sayin..is that shimmed oil relief valves blow up motors.
What I said was that if the relief valve cannot flow enough to keep the pressure at the calibrated pressure (WHEN IT'S OPENED BY HYDRAULIC PRESSURE......WHICH SHOULD NEVER HAPPEN,ANYWAYS,UNLESS SOMETHING IS WRONG INTERNALLY AS WELL....WHICH IS ALSO WHAT I WROTE!!!!!), the pressure will climb and that climbing pressure is bad!!! I have seen backyard butchers put 3 or 4 washers in behind the spring to attempt to raised the pressure on a sacked out engine (which obviously will not work). If the oil filter plugged on that engine, you would see some interesting shit happen......
Think about this: you go to your local auto parts store and buy a shift kit for your auto trans in your musclecar. What is in the kit? A bunch of washers, or a bunch of springs??? The answer, of course..... is springs. Why install a washer to increase pressure when a spring is available? You wouldn't do for valve springs and yet it's fine to do it for this??? I guess it could be argued that since that relief valve should never open, then the washer doesn't hurt anything.....but then why have the valve at all??? You might as well cut a length of steel tube and replace the spring with that.
The washer behind the spring is an old school trick ...and it probably is fine, but there are a lot of old school tricks that are no longer though of as anything other than butchery (using powdered cleanser to seat piston rings used to be commonplace...but not anymore). It is up to the builder to decide......after all even service manuals are opinion....and sometimes the engineer who wrote the manual knows less than the guy who is up to his elbow in the engine.
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entropy
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posted January 06, 2005 11:18 PM
canandamaxxer' I really appreciate your input, and am not doubting you one bit.
you may have summed it up nicely here:
"The washer behind the spring is an old school trick ...and it probably is fine, but there are a lot of old school tricks that are no longer thought of as anything other than butchery"
Thanks much.
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Johnnycheese
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posted January 07, 2005 05:27 AM
quote:
canandamaxxer' I really appreciate your input, and am not doubting you one bit.
you may have summed it up nicely here:
"The washer behind the spring is an old school trick ...and it probably is fine, but there are a lot of old school tricks that are no longer thought of as anything other than butchery"
Thanks much.
I agree except the washer was on the bench, it was free, and I did not have to spring test or sreach for a spring.
Time in money
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canadamaxxer
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posted January 07, 2005 07:42 AM
quote:
quote:
canandamaxxer' I really appreciate your input, and am not doubting you one bit.
you may have summed it up nicely here:
"The washer behind the spring is an old school trick ...and it probably is fine, but there are a lot of old school tricks that are no longer thought of as anything other than butchery"
Thanks much.
I agree except the washer was on the bench, it was free, and I did not have to spring test or sreach for a spring.
Time in money
I hear you on that one!! Time IS money for sure!!
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Ra12r
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posted January 08, 2005 06:45 AM
Canada, YCIS doesn't really understand alot of "Technical Things".....you have to excuse him for just not knowing.
Okay, Canada well everyone I would like to take this one step further. My purpose for "ATTEMPTING" to mildly increase my oil pressure was to "ASSURE" bearing survival. However, we ALL have seen bearing failures where the oil pump and oil levels were not compromised.
So my question is how much force does it take to overcome 20# of oil pressure? This overcome would allow the journal to touch the bearing and kill the motor.
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canadamaxxer
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posted January 08, 2005 10:39 AM
Ra,
That is not an easy question to answer, because there are many more factors involved other than pressure. There is a wedge of oil that is formed as a result of the pressure and the rotation of the crankshaft....which works to prevent the two surfaces from coming in contact with each other. There is a oil film that is present whose job it is to lubricate even when the bearing comes in contact with the journal. There are a zillion different kinds of oil....all with very individual properties. There are differences in maintenance intervals between bikes. To top it all off, what actually IS the oil pressure? It would be very interesting to data log the oil pressure of an engine during riding to see how steady it really is (I'm not so interested in the gradual drop as a result of the engine warming up, as I am in a sudden spike to 0 PSI ).
My theory is that heat is the killer, not simply a lack of oil pressure...and it comes back to coolant choices, radiator size, cooling fan efficiency, air in the cooling system, low oil level (oil is an integral part of the cooling system). If the engine gets too warm, the oil will get thinner and thinner (which makes it harder for the pump to produce pressure as a result of the viscosity vs bearing clearance orifaces), and possibly begin to break down....which can result in coking of the oil which will plug the oil passages and the filter.....and result in a total loss of oil pressure.
I can honestly say that I wish I knew more about this subject, as it is very interesting to ponder. I have popped motors before (while road testing), and don't remember if the engine got hot first, or the heat came afterwards. I do know that once an engine starts to knock (rod knock), catastrophic failure is soon to follow. It could be seconds, or minutes, but it will fail without intervention.
I suspect that cold startup is truly the root cause of engine bearing failures. Think about it: you start your car up at 40 below and it rattles and knocks for 15 -30 seconds. Each knock is physical contact between moving pieces. Even if the PSI of the contact is low, the sheer number of contacts will cause the lead babbit bearings to deform...which will result in an increase in clearances.....and eventually the clearances will be high enough to lower pressure within the oiling system (that is why low viscosity synthetic winter oil helps so much in cold temperatures). This will make the knocking more frequent, as the conditions in which the oil pressure is insufficient to maintain the clearance becomes more common. Even more moderate temperatures cause the engine to rattle a bit on cold startup...and even one contact begins the process. Even the rattle as the engine fills the oil filter is contributing to that eventual bearing failure. I guess the solution to this is one of those accumulator oil bottles plumbed into the oiling system.
This is a mathematical situation IMHO: A+B+C+D+E=F. F is engine failure,E is High performance or increased cylinder pressures, D is heat, C is low oil pressure, B is poor maintenance, A is cold starts. If a person starts removing A B C D and E from the equation, F is less likely to happen. There are no guarantees in life, it's all about managing risks. The engine will last forever is it is never started
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Ra12r
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posted January 10, 2005 08:51 AM
I understand there are others variables. But, let's just deal with one variable, what force is require to overcome 20# of oil pressure coming through the hole in the bearings?
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