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Yes, there is a relationship between flow and pressure in a normal system that is simply pumping as much as it can. This is NOT the case for an OMP. For example, let off the gas completely at 9,000rpm. The stepper motor drops significantly (almost nothing), but you still have near max engine oil pressure. You can go full throttle at 3,500rpm and get near max OMP flow, but have less than max engine oil pressure. There is an oil pressure regulator that keeps engine oil pressure at a specific rate for much of the RPM rev range, where the OMP will supply oil flow based on LOAD, not on RPM.
What relationship are you referring to again?
As long as oil is available to the stepper motor, the stepper motor determines how much oil is supplied, and the pressure of that oil supply has nothing to do with it.
Just because the stepper motor is open max at 9k or any rpm, doesnt mean its getting the same ammount of flow. No? Lets say i have a similar design in a hose for example, at the instant the stepper motor is open a certain ammount, more volume of fluid would pass through the opening with higher pressure. Correct me if im wrong, but could you care to explain why or why not? Yes i am aware MOP is dependant upon load, rpm, throttle pos. but im talking at certain instants.
I don't think you understand how the stepper motor works. It's never "open". It has full control of exactly how much it is flowing, regardless of pressure.
Don't think garden hose. Think a line of kids with buckets as you request them. You can determine how fast they hand you the next bucket in line. It doesn't matter how fast they fill the buckets, you still have complete control over how many buckets you accept from them.
I don't think you understand how the stepper motor works. It's never "open". It has full control of exactly how much it is flowing, regardless of pressure.
Don't think garden hose. Think a line of kids with buckets as you request them. You can determine how fast they hand you the next bucket in line. It doesn't matter how fast they fill the buckets, you still have complete control over how many buckets you accept from them.
Youre correct, i do mot have a full understanding of stepper motors. Correct me if im wrong, youre saying the volume of material the stepper motor allows is regulated? Meaning the stepper motor is set to always allow a certain ammount of material through the system regardless of pressure? By the way im not trying to b a dick or anything just trying to better understand the system and how it works!
Yes, correct. Stepper motors were designed to precisely control how much the driven shaft moves, and in the case of the OMP, that driven shaft only rotates in steps to supply a fixed amount of oil on each step to regulate how much oil is being supplied.
The pressure of the supply won't change the amount regulated.
Yes, correct. Stepper motors were designed to precisely control how much the driven shaft moves, and in the case of the OMP, that driven shaft only rotates in steps to supply a fixed amount of oil on each step to regulate how much oil is being supplied.
The pressure of the supply won't change the amount regulated.
Ahh thank you! Now, my only other question is, how do we know the stepper is getting the same ammount of oil from the SOHN as it is via oil routed from the front casing? Increased vacuum draw? And also i did some really poorly regulated experiments but there was a rather large difference in my oil consumption rates. I will post a picture
Warmed up car after a drive(~35miles) turned off car in a garage(my drive way isnt level) and pulled dip stick(i have 3 extras) so i scored the level, cleaned it off. Went for a drive in the route(no lights one stop sign, plus i went aroung 12pm for no traffic issues or increased run time) and parked in same spot in garage marked with tire chalks in the same direction. Let car cool for aprox 7-10 minutes. Checked the dipstick. Had a box full of 50ml medical plunger things(cant think of the name right now) and added until the oil meniscus was at score mark. And did that 4 times. Well 3 times with that exact way. First time i just found route and video taped driving habit. And yes my MOP rates were aprox 65% over stock from beginning with and without SOHN. Im probably missing stuff but id appreciate any insight!
Your measuring method may be skewing your results.
The temperature of the engine can change the level indicated on the dipstick by as much as half a liter. The first correction to your test method will need to be checking it and measuring it at as close as possible to the same temperature each time, and probably should record that temp each time.
The 2nd improvement is to use something other than the dipstick, due to factors that can influence the result, such as oil dragged up the side of the dipstick tube. Plus it's not all that precise.
I'm not saying your numbers are wrong, but at the moment they are still untrustworthy.
A better method might be to measure actual output via the OMP lines. I'm sure you could figure out a way to run the OMP output into a controlled device to measure how much moves through. If you do this only at idle, it should solve several of your variable factors, such as load (it's known and repeatable). Measure the amount of oil moved through over a specific time duration a few times via each supply method.
I would recommend a heavy premix while you do this.
If there IS a SOHN injection drop, it would be good to know, and it would be good to know how much so injection tables can be adjusted up accordingly. But that test method isn't going to get much traction around here.
Excellent i hope you compression stays well. Only reason i asked just curious of the oils specs. Do you daily drive, weekend, or track it?
Thanks I hope so too but I don't expect a ton of mileage from it since I am turbocharged. It is not a daily anymore and I run Mobil1 0W-40 in the crankcase.
Warmed up car after a drive(~35miles) turned off car in a garage(my drive way isnt level) and pulled dip stick(i have 3 extras) so i scored the level, cleaned it off. Went for a drive in the route(no lights one stop sign, plus i went aroung 12pm for no traffic issues or increased run time) and parked in same spot in garage marked with tire chalks in the same direction. Let car cool for aprox 7-10 minutes. Checked the dipstick. Had a box full of 50ml medical plunger things(cant think of the name right now) and added until the oil meniscus was at score mark. And did that 4 times. Well 3 times with that exact way. First time i just found route and video taped driving habit. And yes my MOP rates were aprox 65% over stock from beginning with and without SOHN. Im probably missing stuff but id appreciate any insight!
If you drove the exact same way and did not romp on it during any of those identical trips, then that might be a somewhat accurate way to measure it. But the consumption rate depends mainly on engine load, not run time or mileage.
Your measuring method may be skewing your results.
The temperature of the engine can change the level indicated on the dipstick by as much as half a liter. The first correction to your test method will need to be checking it and measuring it at as close as possible to the same temperature each time, and probably should record that temp each time.
The 2nd improvement is to use something other than the dipstick, due to factors that can influence the result, such as oil dragged up the side of the dipstick tube. Plus it's not all that precise.
I'm not saying your numbers are wrong, but at the moment they are still untrustworthy.
A better method might be to measure actual output via the OMP lines. I'm sure you could figure out a way to run the OMP output into a controlled device to measure how much moves through. If you do this only at idle, it should solve several of your variable factors, such as load (it's known and repeatable). Measure the amount of oil moved through over a specific time duration a few times via each supply method.
I would recommend a heavy premix while you do this.
If there IS a SOHN injection drop, it would be good to know, and it would be good to know how much so injection tables can be adjusted up accordingly. But that test method isn't going to get much traction around here.
You think all those factors could skew over a 60% margin of error, yes youre right these are very rough estimates. But i do have a sheet where temps were taken. I did ambient. Temp/cabin temp/ humidity/ baro. Pressure/ oil pan temp/ dipstick temp/ i used a bosch laser thermometer, it was calibrated from the shop i used it from about 12 days after.. I have a sheet but im at school and not home. I will post those to see if it helps. I believe temps of oil, did not deviate more than aprox 10 deg F. But im not sure.
And yes right now i premix aprox 20oz per tank. Using motul 800v off road.
I'm not saying that your conclusions are wrong, just that the support for the conclusions is too shaky for any of us to take it at face value. You could have had a wind speed change, a greater load variance than you realize, plus anything else previously mentioned. There is even the possibility that a portion of the oil being consumed ISN'T going through the OMP.
Not being hostile here, just stating that if you want us to agree with you, you are going to have to eliminate as many of those factors as possible. Testing actual output of the OMP in a controlled environment is going to be needed to prove your case. You can physically connect to output via the OMP lines, and you can test it all with the engine at idle which will eliminate load changes as a factor. It would be a much better test, and one that I don't think anyone would argue with.
We could then get on to arguing why it's different So far, we only have suggestions that it is, with no evidence.
And my heavy premix recommendation was for when you have the OMP lines disconnected for the idle test. You are probably over-doing it for normal driving with the OMP connected.
I'm not saying that your conclusions are wrong, just that the support for the conclusions is too shaky for any of us to take it at face value. You could have had a wind speed change, a greater load variance than you realize, plus anything else previously mentioned. There is even the possibility that a portion of the oil being consumed ISN'T going through the OMP.
Not being hostile here, just stating that if you want us to agree with you, you are going to have to eliminate as many of those factors as possible. Testing actual output of the OMP in a controlled environment is going to be needed to prove your case. You can physically connect to output via the OMP lines, and you can test it all with the engine at idle which will eliminate load changes as a factor. It would be a much better test, and one that I don't think anyone would argue with.
We could then get on to arguing why it's different So far, we only have suggestions that it is, with no evidence.
And my heavy premix recommendation was for when you have the OMP lines disconnected for the idle test. You are probably over-doing it for normal driving with the OMP connected.
I don't want anyone to take and live by it. I want people to logically think and experiment, and hopefully someone come with solid evidence. I've seen people with brand new engines, throw a SOHN on there, some people are 90k miles with good compression (premix heavily) other I've seen fail with the SOHN, premix moderately about 10oz per tank and loss of compression within 20k. of course theres too many variables BUT other people on Facebook have also had this experience, and one guy brought up similar finding of oil consumption, with and without SOHN. he found more wear on all parts internally with SOHN than stock MOP. Any ways, i learned some new info, might be cranking up my MOP once again lol but now, I'm saving up for a pcettitracing OTS engine hopefully!
20oz per tank? You better check your fuel pump sock periodically.
checked it about after maybe 3 tanks, nothing yet but since my engine is on its way out i don't drive it anymore, i wanna save up for a new engine and hopefully tear this one down in my own time and hopefully rebuild or sell good parts! And I'm ok with new plugs yearly, can't expect a miracle lol
I don't want anyone to take and live by it. I want people to logically think and experiment, and hopefully someone come with solid evidence.
You aren't asking for anything different than what we are. We are just pointing out the points where your evidence can't really hold up yet. You are on the right track to get to the bottom of the matter, you just have to remove more unknown variables.
Originally Posted by xKp5609x
I've seen people with brand new engines, throw a SOHN on there, some people are 90k miles with good compression (premix heavily) other I've seen fail with the SOHN, premix moderately about 10oz per tank and loss of compression within 20k. of course theres too many variables
Yes, there are many many variables. One example: A large % of engines are lost due to cooling seal failure... it would be inaccurate to assume that the SOHN / OMP / Premix has anything to do with that. Most of those are simple cooling system neglect.
Frankly, the SOHN/OMP can affect only a couple possible failure methods. If you aren't looking at ONLY those failure methods, the findings of casual online surveys are going to be worthless.
Without trying to brag about it, 4.5 years ago I conducted the most thorough survey of engine failures on the forum, including maintenance information, driving style information, modifications, and a bunch of other factors.
I got a total of 108 responses, 2 of those were in January of this year, the 3rd most recent was 11/8/2012. It's more feedback than any other poll or survey done by anyone about this (pretty sure we would have heard of something bigger than this, it would have to show up in the largest RX-8 online community in the world for participants), and it is more thorough with the questions and data points than any other survey as well.
And it is still completely inconclusive. I'd need to cross at least 1,000 responses before I'd have ANYTHING meaningful, and even then it would probably only be on a few points. More than 5,000 would probably be required before I could cover most points with a conclusion.
As time goes on, most owners are not original owners, and would not be able to provide a single piece of information about most of the car's lifespan, so these surveys and polls get even more meaningless.
So be wary of casual surveys with basically no information behind them.
Again...
Originally Posted by xKp5609x
I don't want anyone to take and live by it. I want people to logically think and experiment, and hopefully someone come with solid evidence.
We totally understand this. You just need to take it even farther than you have so far.
You aren't asking for anything different than what we are. We are just pointing out the points where your evidence can't really hold up yet. You are on the right track to get to the bottom of the matter, you just have to remove more unknown variables.
Yes, there are many many variables. One example: A large % of engines are lost due to cooling seal failure... it would be inaccurate to assume that the SOHN / OMP / Premix has anything to do with that. Most of those are simple cooling system neglect.
Frankly, the SOHN/OMP can affect only a couple possible failure methods. If you aren't looking at ONLY those failure methods, the findings of casual online surveys are going to be worthless.
Without trying to brag about it, 4.5 years ago I conducted the most thorough survey of engine failures on the forum, including maintenance information, driving style information, modifications, and a bunch of other factors.
I got a total of 108 responses, 2 of those were in January of this year, the 3rd most recent was 11/8/2012. It's more feedback than any other poll or survey done by anyone about this (pretty sure we would have heard of something bigger than this, it would have to show up in the largest RX-8 online community in the world for participants), and it is more thorough with the questions and data points than any other survey as well.
And it is still completely inconclusive. I'd need to cross at least 1,000 responses before I'd have ANYTHING meaningful, and even then it would probably only be on a few points. More than 5,000 would probably be required before I could cover most points with a conclusion.
As time goes on, most owners are not original owners, and would not be able to provide a single piece of information about most of the car's lifespan, so these surveys and polls get even more meaningless.
So be wary of casual surveys with basically no information behind them.
Again...
We totally understand this. You just need to take it even farther than you have so far.
Well I thank you and hopefully i can find a good environment to further test this out. Appreciate a good discussion!
The pump is a pump It is supplied from a non-pressurized area of the front cover...so the non-pressurized oil from a container is the same
RIWWP...you are a saint
There is no pump in the system, there never was, its just a mechanical stepper... No? And if theres no pressure how does the front cover get oil source? If you day the engine itself, since its not a seperate system, it would still have pressure, granted not as high the whole system, still a pressure. And yes RIWWP does have patience and i feel more knowledge for taking the time to explain things, than sound like hes the engineer mazda paid and thats how it is....
There is no pump in the system, there never was, its just a mechanical stepper... No? And if theres no pressure how does the front cover get oil source? If you day the engine itself, since its not a seperate system, it would still have pressure, granted not as high the whole system, still a pressure. And yes RIWWP does have patience and i feel more knowledge for taking the time to explain things, than sound like hes the engineer mazda paid and thats how it is....
Have you ever seen the front cover removed?...Or taken an OMP apart? Until you do don't be so damn sure you know what's going on.....
If you would like I will repost the pictures of the inside of the OMP and maybe you will understand how it works
Just to check your logic.....is there pressure in the sump of the oil pan?...why not? It is part of the oil system
04-09-2015, 10:35 AM
So far, we only have suggestions that it is, with no evidence.
It is supplied from a non-pressurized area of the front cover...so the non-pressurized oil from a container is the same
