KZScott
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posted July 28, 2011 07:11 PM
oil relief valve mods
so after a lot of thinking and reading about the subject of high vs oem oil pressure i decided to test and see what my relief valve actually opened at instead of just assuming that it was opening at what the factory thought was best. im working with a set of 02 cases, and 01 crank and rods. (the 02 motor had a spun rod bearing so i got it cheap). made an adapter fitting to connect it to an air compressor and when it was first hooked up it had 20 psi in the tank. it leaked a LOT of air! turned on the compressor and i saw no real change all the way up to 100 psi. (the spun bearing comes to mind) took it apart, and out comes the dewalt cordless drill and some valve lapping compound. i gave it a very light job and saw a very fine circle forming on the angled face of the piston-looking-part of the valve assembly. cleaned it, reassembled and checked with air. much better way less air escaping. so i did this 2 more times, each time a little longer, so now there was very little air going past the valve and a little over 60 psi the valve opened and allowed a lot of air to flow. it seemed to close at just under 60 psi. with very repeatable results. (5-6 tries). not sure how accurate the gauge is, but its consistent. now theres been a lot of theories about oil pressure ive read about, one being more is better, another being 10 psi per 1000 rpm, which makes more sense to me than as much as possible, and then some very smart guys say anything more than 80 psi or so is just robbing hp with no real benefit. either way, i was low, so i found a 6mm diameter washer(i think about 1.5mm thick) and that under the circlip gave me an added 20 psi with the same repeatable results.
ill never assume a relief valve is doing its job again! even if it wasnt shimmed, it needed to be fixed!
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
  
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Shane661
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posted July 29, 2011 02:50 AM
 Edited By: Shane661 on 29 Jul 2011 11:16
I plan to make up a setup from an old oil pipe, one with a dedicated high-quality gauge. I know that the one on my Craftsman compressor is a cheapo with poor resolution.
I guess the trend now is for less oil pressure (compared to the 120 psi reliefs out there) and higher volume. On my big 14 motor I have modded cases and a high volume gear. I haven't done anything with the relief yet, but I would like to be able to test it.
I found that McMaster Carr has some very thin/precise shimming washers that would probably do the trick for this sort of project.
Shane
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Bigbore4
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posted July 29, 2011 03:27 AM
Testing the Oil relief with air pressure is really not the way to check it. To be precise, one should rig up a liquid pump, using an oil similar to what you'll be using.
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Shane661
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posted July 29, 2011 03:37 AM
Edited By: Shane661 on 29 Jul 2011 11:39
quote:
Testing the Oil relief with air pressure is really not the way to check it. To be precise, one should rig up a liquid pump, using an oil similar to what you'll be using.
The oil won't compress, but the air will. While there is sure to be some small difference, I think you have to look at the relative results.
I mean, to make it just right you would have to have the exact oil and at the operating temperature, right?
Shane
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Bigbore4
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posted July 29, 2011 04:44 AM
The thing is that the air will find a way around, but with oil, it will have a tendency to equalize clearance to the minimum around the perimeter of the valve, maintaining a smooth operation through the travel of the valve up to the point where it bypasses. Any reasonable oil will give you a much better idea than using air pressure.
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Y2KZX12R
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posted July 29, 2011 05:01 AM
Edited By: Y2KZX12R on 29 Jul 2011 13:01
We did some testing of the stock zx14 relief valve as well as the aftermarket one on the market.
The stock one starts to bleed off pressure at 75 psi and progressively bleeds off more and more until about 90 psi. At that point the valve is full open.
A .010" shim will bump this beginning opening pressure about 10 psi to about 85psi but the curve is longer reaching full open at about 105 psi.
With the HV gear the 75psi (or 85 psi if shimmed) beginning opening pressure is reached at a lower rpm.
Be careful of shimming for very high oil pressures. The filters can burst.
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tcchin
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posted July 29, 2011 08:22 AM
quote:
quote:
Testing the Oil relief with air pressure is really not the way to check it. To be precise, one should rig up a liquid pump, using an oil similar to what you'll be using.
The oil won't compress, but the air will. While there is sure to be some small difference, I think you have to look at the relative results.
I mean, to make it just right you would have to have the exact oil and at the operating temperature, right?
Shane
Pressure is pressure when it comes to measuring bypass valve preload (p/a). Viscosity does not matter unless you're measuring flow rates.
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Bigbore4
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posted July 29, 2011 08:43 PM
"Pressure is pressure when it comes to measuring bypass valve preload (p/a). Viscosity does not matter unless you're measuring flow rates."
Regardless of that, one should use the same medium for testing, as it uses for normal operation.
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tcchin
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posted July 29, 2011 11:37 PM
He did - he used pressure. Spring constants don't change in the presence of oil, and compressibility is not an issue because we're dealing with quasi-static applied pressure, so there's no point in making a senior science project out of this. I would have used a leakdown tester to control the applied pressure, but that's all I would have changed in the test procedure. Besides, I think Scott's point was that the stock relief valve was in need of some gunsmithing to make it seal and perform consistently. Let's not lose sight of the valuable lesson that is the point of this thread. Good job, Scott!
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Bigbore4
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posted July 30, 2011 12:27 AM
Say what you want, but you won't get me to believe that an oil relief valve will act the same and pop at the same pressure, using air pressure rather than oil. I'm not making a "senior science project" out of this, but there is a reason the factories recommend to "not" mess with the internals of the valve.
We, or most of us cannot duplicate the surface finish the factory puts on these.
Nothing wrong with confirming where the valve actually relieves at, but use oil, not air.
You have frictions that are eliminated with using oil, while if you are using air, you will most likely create surface frictions well in excess of what's intended.
If the valve sticks because we've messed with it, all that's going to happen most likely is you'll blow the filter off of it and douse the tires with oil.
Not a big deal, right?
As long as you're sitting in the shop 
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entropy
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posted July 30, 2011 01:49 AM
i've measured the relief psi (shimmed and un-shimmed) with both oil & air, got the same results.
Using air with the leak down tester is just 100X easier and less messy.
Note that it doesn't just pop open at some pressure, it starts to uncover the ports at a pressure and opens more & more with increasing pressure.
That said, be EXCEEDINGLY careful in fooling with that valve.
Sticking closed is not what i am concerned about; if you are very clean, and test the valve after re-assembly, there is no reason it should stick later on.
But, if you assemble and fail to seat that pesky lil circlip properly, you WILL have issues.
I lost a Muzzy billet crank & a set of Carrillo rods, by a friend of mine assembling the valve incorrectly. We put it on the dyno, and after a while power started dropping. Naturally we never checked oil pressure... finally pwr started dropping FAST, dyno operator chopped the throttle but too late. The valve had puked it's clip, spring and piston into the sump, giving something like 20psi at 11500 rpm. All 9 crank journals destroyed, $3900 along with a $1000 set of rods.
It t
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KZScott
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posted July 30, 2011 08:51 AM
quote:
Besides, I think Scott's point was that the stock relief valve was in need of some gunsmithing to make it seal and perform consistently. Let's not lose sight of the valuable lesson that is the point of this thread. Good job, Scott!
yes exactly! untouched im sure I would have toasted this motor in no time from lack of pressure. i think its the reason it died in the first place an became a donor for my project
ill be testing dads soon. its due for an oil change after this wknd and i had planned on pulling the pan just to check and see if theres anything on the bottom(clutch dust ect) that i want out anyway.
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
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Bigbore4
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posted July 30, 2011 08:57 AM
I know what you're saying, but if you think a valve has some issues, just replace it with a new one and shim accordingly. The factory tolerance and finish is near perfect. Only issue may be after it's had some junk run through it.
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KZScott
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posted July 30, 2011 09:09 AM
why replace it when giving it a "valve job" only costs me a few min time? its done and i dont need to wait a couple weeks to get a new one. you dont throw away a head if a few valve seats need attention
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
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tcchin
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posted July 30, 2011 11:29 AM
quote:
...you won't get me to believe that an oil relief valve will act the same and pop at the same pressure, using air pressure rather than oil.
And you will not get me to believe that oil exerts load per unit area differently than air, water, honey, wood or meat. Show me proof that oil-based pressure is different from air-based pressure and I will believe you. Conjecture about "surface frictions" doesn't count. Otherwise, lbf/in2 and N/m2 is all the proof I need that pressure is pressure in a quasi-static (sealed) environment.
If you read Scott's original post again, you'll see that he refinished the sealing surface, not the sliding surface of the valve, so the actuation of the valve is unchanged from stock. Scott's testing proved that he improved the sealing performance of the valve, so I guess he's one of the few who can improve on the factory finish.
Again, good job, Scott, and thanks for sharing! I know what I'll be doing with my oil pressure relief valves from now on.
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Shane661
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posted July 30, 2011 11:47 AM
Edited By: Shane661 on 30 Jul 2011 19:48
quote:
And you will not get me to believe that oil exerts load per unit area differently than air, water, honey, wood or meat.
I have to agree. My experiments with my own meat pressure relief valve back up what Tim is saying. 
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tcchin
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posted July 30, 2011 11:57 AM
Edited By: tcchin on 30 Jul 2011 20:01
Thank God I didn't have to explain that one! 
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entropy
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posted July 30, 2011 01:34 PM
Scott,
now i am curious, and i don't understand what you did.
IIRC, the valve is just a bucket/piston in a cyl with ports.
the spring inside the bucket resists oil pressure on its face.
Increasing oil pressure compresses the spring/lowering the bucket/piston in the cyl until the beveled face starts uncovering the ports at which point oil pressure starts bleeding off.
higher pressure will uncover more of the ports, bleeding more pressure.
if i am remembering it right, what sealing surface did you improve??
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Oz Booster
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posted July 30, 2011 02:54 PM
I would think reading this all through , that the air not sealing in an un matched valve may not have shown quite the same issues using the thicker oil , but its still very good information and well worth the time taken to know exactly whats happening , thanks for letting us know your findings
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KZScott
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posted July 30, 2011 06:11 PM
Karl, the sealing surface of the bucket/piston is not the top of the piston, rather a 45 degree (or close to it, i didnt exactly measure) chamfered edge as the top of the bucket is not "square". the piston is held by the spring into a "valve seat". by shimming the spring you raise the seat pressure or pop off pressure. same basic physics as everything else like this.
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
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entropy
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posted July 31, 2011 03:47 AM
Scott, i just looked at my busa relief valve, and yes the top of the piston sits against the top of the cyl under 0 pressure, but it seems that the real relief happens when the the piston is driven low enough to uncover the ports, directing the oil to the sump...
You seem to be saying that press relief occurs when the piston unseats against the "head", then that pressure works its way around the "skirts' to the ports around the cyl wall.
i'm pretty slo this time in the morning, please tell me how the oil gets to the ports
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Bigbore4
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posted July 31, 2011 06:32 AM
MR tcchin seems to be the guru on this stuff. I'm sure he has an expanation simple enough for us mortals to comprehend
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Bigbore4
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posted July 31, 2011 08:56 AM
This seems to have escalated to something more than "a senior science project".
Might be over my head at this point
Honestly though, as simple as this little valve seems to be, it performs a critical operation and was designed by some fairly smart guys.
I believe like Karl has stated, that the relief comes when the piston uncovers the port, not actually bleeding around the perimeter of the piston.
A subject definetly worth looking into, as I thought I was wrong once and I was mistaken
Not trying to irritate anyone or act like I know more than you guys, as there are some pretty sharp minds around here.
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entropy
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posted July 31, 2011 09:55 AM
Tim - skip this part unless yr helmet is due for replacement (you'll need a bigger size)
Tim Chin is definitely at the very highest end of the smart guys food chain.
Once you get to know him a bit you will experience not just the depth of his tech knowledge/experience on A subject, but also the breadth/depth across MANY tech and not tech and not tech subjects. The guy is amazing.
Tim - you can start here:
I DON'T KNOW for a fact whether the periphery of the oil relief valve is designed to be the bleed off path or not; i just always assumed it was not.
I do know the piston / cyl is a very close fit.
When i did my experiments measuring relief pressure with oil, there was no leakage then all of a sudden oil puked out the ports.
At that point i just assumed the top of piston had reached the port; but who knows, maybe that's when the top of the piston lifted off the seat as Scott is saying.
However, the piston is a very close fit in the cyl, probably (certainly?) less than .001". clearance. I guessing that the rate at which oil could escape around the periphery is very, very low.
Bottom line is that I still believe the ports do the oil relief, but i am certainly willing to keep my mind open and attentively listen to any alternative explanations before i discard them. 
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tcchin
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posted July 31, 2011 10:44 AM
You guys are right. I should probably go change my sanitary provisions and let this subject go.
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