OMP-how it works, modification for AMECU, discussion regarding premix
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Joined: Feb 2001
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From: Dallas
Sometimes I'm sorry I even bother. I guess whoever screams the loudest can call themselves teh winnar.
There is a one way valve present inside the OMP nozzle. This valve allows air to flow from the intake and into the engine, but not the other way around. This one way valve is present because when the engine is not under boost there IS a vacuum present inside the motor. Without this one way valve the engine would in fact suck all the oil it wanted out of the OMP tubes. In fact it would suck up as much as it could and the OMP would not be able to control the amount of oil entering the motor. The one way nozzle provides a leak path from the injector so that when under vacuum it can pull a tiny amount of air into the motor rather than instead sucking all the oil out of the OMP and getting too much. Note that when under boost this one way valve is shut and serves no purpose.
There is a one way valve present inside the OMP nozzle. This valve allows air to flow from the intake and into the engine, but not the other way around. This one way valve is present because when the engine is not under boost there IS a vacuum present inside the motor. Without this one way valve the engine would in fact suck all the oil it wanted out of the OMP tubes. In fact it would suck up as much as it could and the OMP would not be able to control the amount of oil entering the motor. The one way nozzle provides a leak path from the injector so that when under vacuum it can pull a tiny amount of air into the motor rather than instead sucking all the oil out of the OMP and getting too much. Note that when under boost this one way valve is shut and serves no purpose.
Last edited by DamonB; Dec 1, 2004 at 11:54 AM.
i really don't want to copy another pic out of the fsm, since acrobat wont let you cut out excerpts and i have to print them out and wastea a sheet of paper. second gen fsm, section 2, page 7. the picture shows that you can blow through the injector into the engine, but not suck air back out. in ohter words, the engine can suck air in, the intake cannot suck air out, preventing the mop injector from becoming a vacuum leak.
in other words, proving what i said, and the exact opposite of what you said.
if you would like for me to go away and let you guys discuss this to your hearts consent let me know. i thought i would explain some things to you guys, and ususally if someone doesnt agree with what i have to say, i leave it at that and let them figure it out for themselves. all these blatant insults got to me a little, however, so i tried to put a little effort into this thread. oh well, no harm done. after you think about it for a while, and realize how it really works, i'll be glad to answer any more questions you have about the MOP system.
pat
in other words, proving what i said, and the exact opposite of what you said.
if you would like for me to go away and let you guys discuss this to your hearts consent let me know. i thought i would explain some things to you guys, and ususally if someone doesnt agree with what i have to say, i leave it at that and let them figure it out for themselves. all these blatant insults got to me a little, however, so i tried to put a little effort into this thread. oh well, no harm done. after you think about it for a while, and realize how it really works, i'll be glad to answer any more questions you have about the MOP system.
pat
Senior Member
Joined: Oct 2002
Posts: 311
Likes: 1
From: usa
omp
Originally Posted by patman
so, in your turbo engine, after the exhaust has exited, and before tho rotor spins back around to the intake port, you still have compressed air/fuel mixture? guess again, bro.
you still have some exhaust and unburned air/fuel mixture your engine does not have 100% volumetric efficiency.
there is no compressed air left in the engine between after the exhaust port and before the intake port. there is also no engine compression being built until right at the intake port.
actually there is a tiny overlap on the exhaust port and intake port. ok.
if you have a turbo the intake charge is pressurized. that means the intake manifold is under pressure. it also means that as the intake port closes the charge is still under pressure. the check valves that the oil is metered through is to prevent the oil from being pushed out of the housing.
ok
what you need to see is that the engine is 'divided' by the rotor. what is on one side of the rotor is not the same as what is on the other side. this is how you have vacuum on one face and boost on the other. think about it this way: if the turbo fill the whole engine with compressed air/fuel, why doesnt it just push it straight through without ever combusting it?
because the turbo doesn't have enough pressure to turn the engine.
the answer is because it doesnt compress the whole engine, just the area sectioned off by one face of the rotor.
all the area from the compressor side of the turbo through the intake and into the engine is under pressure.
and dont tell me to perform expiriments with my MOP, did you read my other thread? I have just spent a week completely learning everything about how the MOP works. YOU try what you have said. what you will find is that the oil does not squirt out, it drips out. the engine vacuum is the only thing that causes it to move with any velocity at all.
whether the oil drips out of the omp or squirts out it is still pumping oil. you are trying to say that the omp acts in the same way fuel in a carb. IT DOES NOT.
you still have some exhaust and unburned air/fuel mixture your engine does not have 100% volumetric efficiency.
there is no compressed air left in the engine between after the exhaust port and before the intake port. there is also no engine compression being built until right at the intake port.
actually there is a tiny overlap on the exhaust port and intake port. ok.
if you have a turbo the intake charge is pressurized. that means the intake manifold is under pressure. it also means that as the intake port closes the charge is still under pressure. the check valves that the oil is metered through is to prevent the oil from being pushed out of the housing.
ok
what you need to see is that the engine is 'divided' by the rotor. what is on one side of the rotor is not the same as what is on the other side. this is how you have vacuum on one face and boost on the other. think about it this way: if the turbo fill the whole engine with compressed air/fuel, why doesnt it just push it straight through without ever combusting it?
because the turbo doesn't have enough pressure to turn the engine.
the answer is because it doesnt compress the whole engine, just the area sectioned off by one face of the rotor.
all the area from the compressor side of the turbo through the intake and into the engine is under pressure.
and dont tell me to perform expiriments with my MOP, did you read my other thread? I have just spent a week completely learning everything about how the MOP works. YOU try what you have said. what you will find is that the oil does not squirt out, it drips out. the engine vacuum is the only thing that causes it to move with any velocity at all.
whether the oil drips out of the omp or squirts out it is still pumping oil. you are trying to say that the omp acts in the same way fuel in a carb. IT DOES NOT.
i assume you typed your thoughts inside the quote brackets?
anyway, basically we are in agreement on about half of this stuff and you guys are just semi-agreeing with me while calling me an idiot. As i say every time i post, i never said the MOP does not pump, only that it doesnt squirt the oil. to tell you the truth, i dont even remember why this is relevant anymore. obviously the MOP system works. i know how it works. if you disagree with me on that, fine, its not really important. my main interest in the whole thing is the 2-stroke/synthetic thing, which doest really have anything to do with the workings of the actual injection system.
I would assume that you wont argue with the points I made about the advantages of that system a page or so back. If these dont seem like enough incentive to you guys to do a couple hours worth of work, thats ok. They were enough for me, and i like to do things like that anyway, so i figured why not do a writeup so other people know how to do it if they so choose. anyway, thats my speech, and i'm out.
pat
anyway, basically we are in agreement on about half of this stuff and you guys are just semi-agreeing with me while calling me an idiot. As i say every time i post, i never said the MOP does not pump, only that it doesnt squirt the oil. to tell you the truth, i dont even remember why this is relevant anymore. obviously the MOP system works. i know how it works. if you disagree with me on that, fine, its not really important. my main interest in the whole thing is the 2-stroke/synthetic thing, which doest really have anything to do with the workings of the actual injection system.
I would assume that you wont argue with the points I made about the advantages of that system a page or so back. If these dont seem like enough incentive to you guys to do a couple hours worth of work, thats ok. They were enough for me, and i like to do things like that anyway, so i figured why not do a writeup so other people know how to do it if they so choose. anyway, thats my speech, and i'm out.
pat
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Joined: Feb 2001
Posts: 9,617
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From: Dallas
For everyone's viewing pleasure here is a pic of a disassembled third gen OMP
At the far right is the stepper motor. All this motor does is move the little nub in the middle in and out. Just left of the stepper is a large plunger with a spring. This is the actual valve that controls the amount of oil admitted through the pump and it fits into the bore of the OMP. The stepper motor is responsible for deciding the position of this valve and thus regulating oil volume. Just below the large plunger is a smaller plunger. This smaller plunger also acts as a simple regulator and it resides in the bottom left of the OMP in the pic. Just inside this bore you can make out the single piston PUMP which is driven by a cam inside the OMP that runs off the tang on the front cover. There is an additional sensor on the back which is hidden in the pic. This sensor is merely a linear potentiometer that the ecu uses to be certain of the stepper motor driven valve's position. That's why on the FD there are two OMP error codes possible, one for the stepper motor and one for the position sensor. I actually had the position sensor fail and even though the OMP was actually working perfectly fine the ecu went into limp mode since it couldn't be sure the stepper motor was working correctly without feedback from the position sensor. In my case I could have merely installed a new position sensor if they were available.
Ahhhh. That's all well and good you say, but what of the old mechanical OMP's in other gens? They work just the same and we have better pics of them disassembled! The "mechanical" OMP work the same except the valve adjustment is purely mechanical, there is no stepper motor.
I believe this is from an FC. You can clearly see the plunger mechanism which the tang drive from the front cover powers in order to generate pressure.
At the far right is the stepper motor. All this motor does is move the little nub in the middle in and out. Just left of the stepper is a large plunger with a spring. This is the actual valve that controls the amount of oil admitted through the pump and it fits into the bore of the OMP. The stepper motor is responsible for deciding the position of this valve and thus regulating oil volume. Just below the large plunger is a smaller plunger. This smaller plunger also acts as a simple regulator and it resides in the bottom left of the OMP in the pic. Just inside this bore you can make out the single piston PUMP which is driven by a cam inside the OMP that runs off the tang on the front cover. There is an additional sensor on the back which is hidden in the pic. This sensor is merely a linear potentiometer that the ecu uses to be certain of the stepper motor driven valve's position. That's why on the FD there are two OMP error codes possible, one for the stepper motor and one for the position sensor. I actually had the position sensor fail and even though the OMP was actually working perfectly fine the ecu went into limp mode since it couldn't be sure the stepper motor was working correctly without feedback from the position sensor. In my case I could have merely installed a new position sensor if they were available.
Ahhhh. That's all well and good you say, but what of the old mechanical OMP's in other gens? They work just the same and we have better pics of them disassembled! The "mechanical" OMP work the same except the valve adjustment is purely mechanical, there is no stepper motor.
I believe this is from an FC. You can clearly see the plunger mechanism which the tang drive from the front cover powers in order to generate pressure.
Last edited by DamonB; Aug 31, 2005 at 08:46 AM.
Senior Member
Joined: Jan 2004
Posts: 341
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From: Colorado
Great pics, thanks a lot.
Still what I am missing about this whole discussions and it does effect a lot of us, is what to do with the vacuum lines that hook up to the injectors. What do they do? Are they necessary? Do you need vacuum on them? If you don't run the stock intake you lose the place where they were hooked up to.
Anyone really knows?
CW
Still what I am missing about this whole discussions and it does effect a lot of us, is what to do with the vacuum lines that hook up to the injectors. What do they do? Are they necessary? Do you need vacuum on them? If you don't run the stock intake you lose the place where they were hooked up to.
Anyone really knows?
CW
Obsessed
Joined: Sep 2003
Posts: 453
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From: Lenexa KS
Yes, because the NA models don't see boost in the UIM. The FD routes to its only source of consistent vacuum - before the compressor. Some vacuum is desired at the injector in order to keep the injector valve sealed by default, but negative pressure in the combustion chamber is ample to overcome this when air is needed (to avoid sucking the oil lines dry).
I think the differences of opinion are mostly semantic. The pump is "providing" a metered dose (a drop is probably right - if it was "squirting" you'd be burning an awful lot of oil). The oil is at sufficient pressure to be forced into the housing against boost pressure if necessary, or it can be "sucked" in... it doesn't really matter, as the injector valve effectively facilitates either scenario by its design. Regardless of the pressure in the housing, oil gets in... that, I'm sure, was the design objective.
I think the differences of opinion are mostly semantic. The pump is "providing" a metered dose (a drop is probably right - if it was "squirting" you'd be burning an awful lot of oil). The oil is at sufficient pressure to be forced into the housing against boost pressure if necessary, or it can be "sucked" in... it doesn't really matter, as the injector valve effectively facilitates either scenario by its design. Regardless of the pressure in the housing, oil gets in... that, I'm sure, was the design objective.
I did some research and are giong this route. Synthetic in the engine and 2 stroke through the OMP. Best of both worlds
Originally Posted by the_glass_man
Where and how much are the RA adapters? I can't seem to find them anywhere on their site.
Senior Member
Joined: Nov 2001
Posts: 268
Likes: 37
From: San Francisco Bay Area, California
If this has been written up elsewhere, I apologize - I tried searching but I'm not going to read *every* thread that comes up.
What I don't see written is how the oil is metered. It makes sense to me that the OMP actually starts to close at higher RPM, not open. I'm not saying that it injects less oil - only that it restricts the flow from the pump which is tied into engine RPMs. The total amount would be constant or only slightly greater. Oil doesn't have to be metered like an air-fuel ratio if it's injected. That ratio is really just important if you're pre-mixing. Injected, the oil doesn't combine with anything so why would you need a ratio other than too much oil could cause detonation. That would explain the greatly varying reports of how much oil you really need. I can't see it being the other way around with the OMP increasing oil at higher RPM. At idle, where would the pressure come from to over-lubricate the housings? So what I really want to know if if 50% efficiency (OMP unplugged) is fine with pre-mix oil (through PVT Technologies conversion), because if the OMP functions the way I suspect, there would actually be quite a bit more oil going in at redline. (OMP restricting at only 50%.)
If I'm totally wrong, let me know or point me to the relevant thread. Thanks guys!
What I don't see written is how the oil is metered. It makes sense to me that the OMP actually starts to close at higher RPM, not open. I'm not saying that it injects less oil - only that it restricts the flow from the pump which is tied into engine RPMs. The total amount would be constant or only slightly greater. Oil doesn't have to be metered like an air-fuel ratio if it's injected. That ratio is really just important if you're pre-mixing. Injected, the oil doesn't combine with anything so why would you need a ratio other than too much oil could cause detonation. That would explain the greatly varying reports of how much oil you really need. I can't see it being the other way around with the OMP increasing oil at higher RPM. At idle, where would the pressure come from to over-lubricate the housings? So what I really want to know if if 50% efficiency (OMP unplugged) is fine with pre-mix oil (through PVT Technologies conversion), because if the OMP functions the way I suspect, there would actually be quite a bit more oil going in at redline. (OMP restricting at only 50%.)
If I'm totally wrong, let me know or point me to the relevant thread. Thanks guys!
Last edited by HyperRex; Aug 12, 2005 at 05:38 PM. Reason: speeling errors
Rotary Freak
Joined: Jan 2004
Posts: 1,890
Likes: 4
From: Belgium
I guess the electrnoic will still work with the OMP disconnected. However, the mechnical is just an adaptor and uses the OMP for oil flow.
At least that's what I understood from RA's mail I got about this
At least that's what I understood from RA's mail I got about this
Rotary Freak
Joined: Jan 2004
Posts: 1,890
Likes: 4
From: Belgium
True, that's why I don't like premix for a car. Premix is something from the motorcycle world and finds it's history in carburator içnjection. Overal the holes in a carburatorare quite a bit bigger than the holes in an injecor for a car. In my opinion increasing the possibility to have a sticky injector when the car was not running for a long time, cold weather, almost empty tank with higher oil concentration.
Given the fact we drive rotaries I'm not that fond of those things.
I think the RA OMP adaptor can provide a solution there, allowing you to chose your oils. Motor oil for lubrication, 2 stroke synth which is designed to burn (or to disintegrate)
This is a combination which is hard, if not impossible to achieve, at least when you want to keep your car running with it for a long time.
On the other hand you must ask yourself how 'good' the quality of the lubrication is of motor oil being pumped into the rotor chamber. No wonder emissions are that bad.
I'm on for the RA adaptor and I'll be oredering it together with my rebuild kit.
Small tank with a dipstick from a coolant reservoir and a simple electronic piece of wiring to warn me when it's near empty.
Given the fact we drive rotaries I'm not that fond of those things.
I think the RA OMP adaptor can provide a solution there, allowing you to chose your oils. Motor oil for lubrication, 2 stroke synth which is designed to burn (or to disintegrate)
This is a combination which is hard, if not impossible to achieve, at least when you want to keep your car running with it for a long time.
On the other hand you must ask yourself how 'good' the quality of the lubrication is of motor oil being pumped into the rotor chamber. No wonder emissions are that bad.
I'm on for the RA adaptor and I'll be oredering it together with my rebuild kit.
Small tank with a dipstick from a coolant reservoir and a simple electronic piece of wiring to warn me when it's near empty.
Originally Posted by luiml73
I just completed my setup. Here's a few pics of the adapter and the oil reservoir tank.
