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Richard Sohn OMP (MOP) Adapter

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Richard Sohn OMP (MOP) Adapter

Old 08-08-2007, 11:50 AM
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Great pictures ayrton012. May I suggest some terminology so there is no confusion:

Eccentric shaft: Is in the engine, the equivalent of a crankshaft in a piston engine.
Pump input shaft: engages the eccentric shaft through a key and internal engine gearing. It contains two worms that engage two gear shafts.
Gear Shafts: On one end they are keyed to pistons and in the other they contain cutouts that engage the circular part of the control shaft. They also appear to contain a central protrusion (button) which engages a cam on the control shaft.
Control Shaft: Is connected to a sector gear that is in turn geared to the stepping motor. The stepper rotates the control shaft which positions the cam.
Pistons: Contain holes and simultaneously rotate/translate via a keyed connection to the geared shafts.
Valves: Are inside the pistons

I had thought the small button on the bottom of the gear shaft was actually the end of the valve that protruded through a hole in the gear shaft. However it now appears that this is not the case, and the buttons are in fact part of the gear shaft. So this is what I think we know so far:

-The pump input shaft rotates at half the speed of the eccentric shaft.
-From the pictures, the geared shafts appear to be identical and appear to have about 16 teeth (Is this where your 16 comes from), so they would turn at 1/16 the rate of the input shaft, and 1/32 the rate of the eccentric shaft (can you better explain the 1/36 if that is what you really mean)
-The piston simultaneously reciprocates and rotates. Its reciprocating rate is twice its rotation rate.
-When the control shaft is rotated, the cam engages the button on the geared shaft, and prevents it from fully seating on the control shaft.
-The maximum axial position of the pistons occurs when hemispherical cutout on the geared shaft is at right angles to the control shaft.
-The piston stroke moves down from there. The maximum length of stroke is when the flat part of the cam is at right angles to the axis of the button (geared shaft).
-The valves are fixed in position.
-The springs only serve to return the piston and ensure the geared shaft is always in contact with the control shaft.

Any Comments?

And then there are more questions:

-If this is a positive displacement pump whose stroke rate is controlled by engine speed, and whose stroke length is controlled by the PCM, then what are the valves for?
-What is the direction of oil flow and are the valves on the inlet or outlet?
-Are the four holes in the pistons related to the four outputs? And why are two of these holes drilled at an angle? And at least one of the pistons has two more holes on the other side.
-What is the relationship of the valve steps and the piston holes.
-What do the inside of the cylinders (that the pistons slide in---part of the casting) look like? They must have grooves of some sort.
-what is the position of the cam when the sector gear is at zero position (against the mechanical stop)?
-Why could no flow be observed when the pump input shaft was rotated with a drill. Is it just too low?
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Old 08-09-2007, 04:36 AM
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From the pictures, the geared shafts appear to be identical and appear to have about 16 teeth (Is this where your 16 comes from), so they would turn at 1/16 the rate of the input shaft, and 1/32 the rate of the eccentric shaft (can you better explain the 1/36 if that is what you really mean)
Yes, you are right, i really wanted to write 1/32.

The pump input shaft rotates at half the speed of the eccentric shaft.
-From the pictures, the geared shafts appear to be identical and appear to have about 16 teeth (Is this where your 16 comes from), so they would turn at 1/16 the rate of the input shaft, and 1/32 the rate of the eccentric shaft (can you better explain the 1/36 if that is what you really mean)
-The piston simultaneously reciprocates and rotates. Its reciprocating rate is twice its rotation rate.
-When the control shaft is rotated, the cam engages the button on the geared shaft, and prevents it from fully seating on the control shaft.
-The maximum axial position of the pistons occurs when hemispherical cutout on the geared shaft is at right angles to the control shaft.
-The piston stroke moves down from there. The maximum length of stroke is when the flat part of the cam is at right angles to the axis of the button (geared shaft).
-The valves are fixed in position.
-The springs only serve to return the piston and ensure the geared shaft is always in contact with the control shaft.
Absolutely, as you said!

-
If this is a positive displacement pump whose stroke rate is controlled by engine speed, and whose stroke length is controlled by the PCM, then what are the valves for?
We know that the valves (according to your term.) are fixed. When the piston (one of the two) move "down", it's inside is filling up with oil. When the pistons move up, te fixed valves are pushing the oil out from the inside of the pistons (and from the MOP) to the oil nozzles. According to these: when the pistons are filling up with oil, the piston's holes are connected to the other holes of the MOP ( to the "filler" holes). After that the piston rotates and it's holes get connection with the MOP's outer holes (to the nozzles), just then when the piston moves up and the oil is pushing out from it's inside, by the fixed valve. I hope you know what I mean!

-Are the four holes in the pistons related to the four outputs? And why are two of these holes drilled at an angle? And at least one of the pistons has two more holes on the other side.
Some of the holes are for filling up with oil the piston, and some of them are for let out the oil to the nozzle's way. These holes are changing their positions by the pistons rotating and vertical moving (up and down in my theory, but if you see the MOP on the engine it's horizontally moving). Every piston has two out (to the nozzles) holes in the MOP's housing. So only two holes of one piston can get connection in the same time with the two MOP's out (to the nozzles) holes. When this holes are connected this way, the other holes are closed. So the oil has only one way to get out from the piston. The closing of the other holes is caused by the MOP's house and the pistons position. Of course when the piston gets the oil, the out (to the nozzles) holes are closed, and so on....

-What is the relationship of the valve steps and the piston holes.
One of the pistons inside are bigger (more oil), and the other has smaller. Some engine's working phase (low rpm) only the smaller piston work, which is caused by the control shaft. In some phase (high rpm,VOT)all of the two pistons are working.

-What do the inside of the cylinders (that the pistons slide in---part of the casting) look like? They must have grooves of some sort.
The piston's inside is just like a cylinder. See them like the piston is a cylinder, and the fixed valves are the pistons. In this case the cylinder moves up and down, and the pistons are fixed.

-Why could no flow be observed when the pump input shaft was rotated with a drill. Is it just too low?
Yes, the driller was to slow, and I used too big diameter pipes at the out of the MOP, so now I think that test was false. Otherwise the oil dropped out sometimes these pipes. I was not convinced by the drops. But now i think the low rpm caused this weak "oil out".
Attached Thumbnails Richard Sohn OMP (MOP) Adapter-dscf0188.jpg   Richard Sohn OMP (MOP) Adapter-dscf0190.jpg  

Last edited by ayrton012; 08-09-2007 at 04:39 AM.
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Old 08-14-2007, 01:58 AM
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What would happen if the small needle assembly was swapped for a large one ( would they fit??).....with 2 large bore needles the pumping capacity would be much larger at low loads.....
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Old 08-14-2007, 02:40 AM
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What would happen if the small needle assembly was swapped for a large one ( would they fit??).....with 2 large bore needles the pumping capacity would be much larger at low loads.....
Yes, the larger one outer diameters are the same with the smaller one. I tried, the fitting is ok.

The pumping capacity will be much higher at low and high rpm too. I think that would be too much oil for the engine.
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Old 08-14-2007, 07:18 AM
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Well done ayrton012. From what you have found out, I think a redefinition of terms is needed. May I suggest:

-Needle Valves: There ain't none. Forget about it. Don't got no stinkin' needles.
-Needles become pistons.
-Pistons become cylinders.
-Cylinders become, say, housing.

Do you know:
-Which direction the pump shaft turns?
-How do you know that the pump shaft turns at 1/2 the eccentric shaft?
-Are the two gear shafts offset such that as one cylinder moves out the other moves in (180 degree motion out of phase, but 90 degree relative pump shaft orientation), or do they both move together.
-Why do you have this pump? Did your original fail?

I am interested in the above because it pertains to me possibly getting a extra pump.

Do you know why the pistons have steps in them? Do the cylinders also have stepped bores?

Last edited by Delmeister; 08-14-2007 at 07:29 AM.
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Old 08-14-2007, 11:09 AM
  #106  
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-Which direction the pump shaft turns?
You see it on the pics below.

-How do you know that the pump shaft turns at 1/2 the eccentric shaft?
I turned the flywheel of a Renesis by hand, and watched the MOP's driving .... . This engine was out from a car, in a Mazda service shop. It was allowed for me (thanks for them).

-
Are the two gear shafts offset such that as one cylinder moves out the other moves in (180 degree motion out of phase, but 90 degree relative pump shaft orientation), or do they both move together.
I don't know exactly, because this MOP was inspected (assembled out)before I've got it, so maybe the positions of the parts was not the original. But we know, - as you see on the second pics - the position of the shaft's cam are the same. Otherwise there are some differences between the two cams, because only the one of the cylinders moves up-down (a little) when the engine's rpm is low.

-Why do you have this pump? Did your original fail?
It is not mine, but it was replaced because of failing in an other car.

Do you know why the pistons have steps in them? Do the cylinders also have stepped bores?
Yes.

I have one more though. The cylinders (mainly the one of them) have little oil filler holes(where the cylinder inside is filling with oil). These holes are in contact with the holes of the MOP's housing, for a very liitle time, mainly at high rpm. Is the gravity feed (RS adapter)pressure enough to fill the cylinders, or the engine oil pressure is better (original)? Or the little vacuum in the cylinder's - after pushing out the oil to the engine's nozzles - is help to fill them with oil?
Attached Thumbnails Richard Sohn OMP (MOP) Adapter-dscf0185.jpg   Richard Sohn OMP (MOP) Adapter-mop22222.jpg   Richard Sohn OMP (MOP) Adapter-mop3333.jpg  
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Old 08-14-2007, 12:02 PM
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Originally Posted by dannobre View Post
What would happen if the small needle assembly was swapped for a large one ( would they fit??).....with 2 large bore needles the pumping capacity would be much larger at low loads.....
You could probably just interchange the two piston/cylinder assemblies. Then the large piston would be delivering the oil most of the time.
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Old 08-21-2007, 09:40 AM
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Originally Posted by ayrton012 View Post
I have one more though. The cylinders (mainly the one of them) have little oil filler holes(where the cylinder inside is filling with oil). These holes are in contact with the holes of the MOP's housing, for a very liitle time, mainly at high rpm. Is the gravity feed (RS adapter)pressure enough to fill the cylinders, or the engine oil pressure is better (original)? Or the little vacuum in the cylinder's - after pushing out the oil to the engine's nozzles - is help to fill them with oil?
As far as I can see, nothing will fill the cylinders except the force of the springs pushing them away from the pistons and creating a vacuum. The external pressure does no good because it is equal all around (I assume the holes evident in the end-cap area connect to the oil gallery), but something must be there to ensure everything is submerged in oil. The cylinders have static surfaces on both sides and on very cold days when the oil is viscous, the forces required to shear the two thin oil films can be quite high. It makes you wonder that if the springs are not strong enough to completely force the cylinders and pistons apart quickly enough, whether the stroke length could be reduced.


I just got a used pump and am going to look at it internally, but I don't want to screw it up. Can you tell me:

- What failed in the pump you have? I appears to be in good shape (electrical?)?
- If you look into the outlets, you will see four brass screws with the slots all lined up the same way. Have you removed any of these, and if so what do you see, including the accesses in the housing?
- Are there any press fits, or does the whole thing disassemble without forcing anything?
- The wire colours on the pump connector do not match those that appear on the schematic, at least for the pump side of the connector (I have not looked at the harness side). For example both the center wires are supposed to be W/R (white base, red stripe). Do you see these colours on your pump connector?
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Old 08-22-2007, 04:38 AM
  #109  
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As far as I can see, nothing will fill the cylinders except the force of the springs pushing them away from the pistons and creating a vacuum. The external pressure does no good because it is equal all around (I assume the holes evident in the end-cap area connect to the oil gallery), but something must be there to ensure everything is submerged in oil.
Yes, maybe the vacuum the only one thing, which responsible filling the cylinders with oil, and the external pressure is equal all around in the MOP...But.. the external pressure is *separated from the inside of the cylinders. The pressure only then can get into those, when the filler holes are connected.
*separated: of course the oil film is the only sealing between the parts. The cylinder's end (one of the two end side) is closed, and the other side of it is closed by the piston.

- What failed in the pump you have? I appears to be in good shape (electrical?)?
Yes, it had electrical problem. The stepping motor stopped in limp mode.

If you look into the outlets, you will see four brass screws with the slots all lined up the same way. Have you removed any of these, and if so what do you see, including the accesses in the housing?
I did not remove these screws, but I tried that these screws does not separate the inner and outer part of the MOP's outlet. There are a little bore in the center of these screws.

- Are there any press fits, or does the whole thing disassemble without forcing anything?
You can easily disassemble everything, except the casted main house.

You can see my wiring on the pics.

I'm glad that you got a MOP. I hope it will help our efforts to solve the mystical MOP theme.

...I forged about the viscosity: I always thought, that a 0w- oil is better, using the MOP.
Attached Thumbnails Richard Sohn OMP (MOP) Adapter-mopwires.jpg  

Last edited by ayrton012; 08-23-2007 at 03:59 AM.
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Old 08-24-2007, 04:42 AM
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Thanks for the picture ayrton012. The wires appear to be the same as mine, and certainly not what appears in the schematic, although this may only refer to the harness side.
I did not remove these screws, but I tried that these screws does not separate the inner and outer part of the MOP's outlet
I don't quite understand. Do you mean to say that you tried to remove them but were unable to?


I'm glad that you got a MOP. I hope it will help our efforts to solve the mystical MOP theme.
See this post for results of an initial investigation.
Originally Posted by Delmeister View Post
Pre-Phase 1 – MOP Basic Data Gathering (see post #1 for views)
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Old 08-24-2007, 10:55 AM
  #111  
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I don't quite understand. Do you mean to say that you tried to remove them but were unable to?
No, I did not try to remove them. I just used a narrow pin, and recognized that there is a bore in the center of these screws. So the screw"s function is narrowing the MOP's outlet bore.

Pre-Phase 1 – MOP Basic Data Gathering (see post #1 for views)

This link is not working for me.
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Old 08-24-2007, 01:56 PM
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Click on the little arrow after my name in the quote box, not the underlined heading below it (which I agree looks like a link).

Hard to believe that the screws just present straight through tiny holes. The holes could have just been drilled directly from the top if that is all that was needed. Why go to the bother of making large holes and then closing them off with brass screws? Also, the screw slots are all lined up (in my pump at least, and exactly 90 degrees to the cylinder bores - are they in yours?), all of which suggests there is probably more to their function than meets the eye (maybe a check valve to keep oil from draining back from the outlet lines when the car is sitting?). I will eventually look when I am better organized to take the pump apart but feel free to take a shot at it in the meantime if you're curious enough.
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Old 08-25-2007, 05:04 AM
  #113  
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Thanks, the link is working!
You were right. The "screws" are valve! But, as you see on the pics, the valve only according to the cylinder1 outlet. The valve screw broke apart when I tried to get it out. I don't know how these were fixed in the factory(maybe pressed)?
Attached Thumbnails Richard Sohn OMP (MOP) Adapter-mopoutlets2.jpg   Richard Sohn OMP (MOP) Adapter-mopoutlets3.jpg   Richard Sohn OMP (MOP) Adapter-mopoutlets1.jpg   Richard Sohn OMP (MOP) Adapter-mopoutletvalve.jpg  

Last edited by ayrton012; 08-25-2007 at 06:14 AM.
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Old 08-25-2007, 11:35 AM
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Great stuff! sorry you broke the screw - I'll help compensate you for it if you want to try and repair it. Right now I'm going to be away for a week or so, and will take a better look at the picturese when I get back.
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Old 08-27-2007, 02:17 AM
  #115  
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Originally Posted by Delmeister View Post
Great stuff! sorry you broke the screw - I'll help compensate you for it if you want to try and repair it. Right now I'm going to be away for a week or so, and will take a better look at the picturese when I get back.
Thanks, but this MOP is only for analyzing. I don't want to rebuild it.
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Old 09-03-2007, 11:20 PM
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OK I'm pretty sure I know how this thing works now.

First of all take a look at these attachments (courtesy of two rotors). It doesn’t tell you how it works but it shows some internal porting.

Secondly, there is a saying that if all rational attempts at explaining some phenomenon fail, then the explanation lies in what has been perceived as irrational.

We have to give up the idea that all outlets are created equal. More specifically, two of the outlets have different flow than the other two. Look at the outlets straight on with the end cap region (spring chamber) to the right. Call the top left outlet #1 and count going counterclockwise, so the top right outlet become outlet #4. Then outlets #1 and #2 have less flow than the other two.

If you look at the picture in ayrton012’s last post showing the four outlets you will see a couple of metal ***** that have been forced into holes that seal holes drilled from the outside which penetrate into the common oil gallery shown in the attached figure. If you look to the side of the housing (not visible in photo) you will see four sealed holes. One of the top two were drilled to connect outlets #1 and #2 with the angled hole in the cylinder encasing the small diameter of the small piston. The other top hole connects outlets #3 and #4 with the angled holes in the cylinder encasing the big diameter of the small piston. These holes discharge into the top part of the outlets, that is above the check valves. The bottom holes do the same but for the big piston, with the discharges being below the check valves.

So here’s how it works. In the attached figure you see all diameters of all pistons sucking up oil from the oil gallery. As the cylinders are simultaneously rotated 90 degrees and pushed towards the cylinder, the angled holes come in line with say drilled holes leading to #2 and #3 outlets, both above and below the check valves. Further rotation of another 90 degrees and retraction of the cylinders brings the other side of the cylinder inlet holes into contact with the oil gallery for sucking up oil. Another cycle and outlets #1 and#4 receive oil. Each outlet is assured its share of oil.

A couple of questions remain. For one, why should there be two separate oil flows? It is unlikely that the differences stem from the front and rear rotors. More likely is that the differences between the services that the side seals see depending on whether they are located in the end or intermediate housings. There seems a lot more action going on for the volume of material in the intermediate housing. Both rotors discharge their exhaust there. Also most of the intake is going on there. The highest temperature in the system (exhaust) is separated from the lowest (intake) by just a short distance. It would seem therefore that the two nozzles discharging on either side of the intermediate housing might get more oil (outlets #3 and #4)

The other question is – why the check valves? I believe the reason for this is that the big piston is not pumping most of the time. It is only brought in for extreme requirements. Most of the time the cylinder encasing the big piston simply spins without reciprocating. Because the oil flows from the small piston are so very low, it could be that a significant portion could leak through the big cylinder/piston assembly and the check valves are there to prevent that.
Attached Thumbnails Richard Sohn OMP (MOP) Adapter-mop1.jpg   Richard Sohn OMP (MOP) Adapter-mop2.jpg  
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Old 09-07-2007, 11:02 AM
  #117  
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The other question is – why the check valves? I believe the reason for this is that the big piston is not pumping most of the time. It is only brought in for extreme requirements. Most of the time the cylinder encasing the big piston simply spins without reciprocating. Because the oil flows from the small piston are so very low, it could be that a significant portion could leak through the big cylinder/piston assembly and the check valves are there to prevent that.
I agree with you!

For one, why should there be two separate oil flows?
I don't think there are different oil flow between the two nozzles per rotor(engine), and between the two rotor. There are only minimal time delay between the oil flow of the nozzles.
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Old 09-10-2007, 02:14 AM
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Originally Posted by ayrton012 View Post
I don't think there are different oil flow between the two nozzles per rotor(engine), and between the two rotor. There are only minimal time delay between the oil flow of the nozzles.
Are you saying that you think all four nozzles receive the same amount of oil averaged over time? The oil delivery is pulsed and so there is a small time delay between deliveries but what I am saying is that on average, outlets #1 and 2 receive less oil than outlets #3 and 4.
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Old 09-10-2007, 06:29 AM
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Thoughts/Questions about Sohn OMP Adapter

Pardon the interruption here, but I'm in need of some expert guidance.

Let me preface this by saying that I have never owned a rotary, but I am highly interested in getting an RX-8. They are such hot looking cars, and I am intrigued by the engineering of the Renesis engine.

From what I've gathered it appears that the Sohn OMP Adapter is a near-perfect solution to the Renesis' apex seal failure issue. I say near-perfect because it still requires extra effort (relative to a piston engine) from the owner--installation, maintaining both engine oil and apex seal oil. But this is surely no more difficult than working with the OEM setup. You already have to top up regularly, but you can enjoy the extended oil change interval of synthetic oil. And you have the peace of mind that you won't end up a member of the New Engine Club. So... why isn't everyone with an RX-8 doing it?

The only two stoppers I can think of are (1) fear of voiding warranty and (2) disinclination to dedicate time/money towards maintenance. I can understand the latter because people would rather spend their time doing other things, especially if they are under warranty. However, I (and others on this forum I'm sure) am in it for the long haul, and warranties expire. My current vehicle has been very reliable ('96 Infiniti G20), and I wouldn't buy a new car if I wasn't confident it would last.

And since using the right oil for each job is nothing but good for the engine, how could this mod void the warranty? This is where I'm stuck. I can only point to "unofficlal" sources for evidence that using the adapter will make the engine perform more reliably. It makes perfect sense to me, but I'm no rotary expert. (What are the apex seals made of anyway? an elastomer of some kind?) And I don't doubt that Mazda would try to void your warranty for it, even though they can only legally do so if it caused the problem.

So, beyond the argument given by Richard Sohn in post #2 in this thread, what evidence do we have that his adapter will improve the long-term reliability of the Renesis. It is clearly evident that it is good for a racing application--Idemitsu premix is labeled "Racing"--but is there a consensus that it is good for a street-driven engine? (e.g. would the OMP injection rate be non-ideal when premix/two-stroke is used instead of engine oil)
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Old 09-10-2007, 08:18 AM
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.......... but you can enjoy the extended oil change interval of synthetic oil.

You don't have your eight yet, but have already made an assumption that is not backed up by data.

Who said synthetic is "not ok" if it is injected/burned?

Who said a Sohn adapter makes synthetic "acceptable?"

S


(The seals are made of iron......)
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Old 09-10-2007, 08:33 AM
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Apex Seals
If you look at the attachment I included a couple of posts ago, Mazda says the oil injection is for the side seals. I don't know exactly what the Apex seals are made of but they are of a hardened metal. In fact for the Renesis, they claim to have introduced some new hardening technology (electron beam I believe). I don't know about the Apex seal failure issue, but I do know the stress put on these cars varies enourmously with drivers. My guess is that any issues are due simply to the fact that this car attracts a larger proportion of people who frequently like to push the engine to its limits.

Some Possibilities as to why Mazda didn't do it
-There is no benefit, or possible harm, to using a separate oil reservoir for injecting more 'suitable' oil. I have looked for but have not found anything that could be called scientific evidence as to its effects. One area I have been concerned with is the pressure needed to fill the cylinders, particularly at the cold temperatures (high oil viscosity) where I live. This pump has very little capability of sucking in oil. I asked Richard about this pressure and he responded with "This pressure has not been measured, however, the oil enters the OMP right at the outflow of the oil into the oil pan. This can only be visualized on the actual hard ware, since a real picture of it does not axist to my knowlege". I may eventually attempt to measure this pressure and do some bench testing at different temperatures to see how oil flow is affected.
-If there is benefit, it may not be significant enough to outweigh the negative marketing reaction towards the car from non-enthusiasts because of the need of a separate oil reservoir. I'd put my money on this one.

Warranty
By installing this adapter, you would be introducing another level of responsibility, with the onus on yourself to ensure you knew why you overrode Mazda's reasoning for not doing it that way, and that you fulfilled your responsibility of ensuring the reservoir never ran dry. If an engine failure could be traced to the targeted area (say the side seals) then it is my belief that you could justifiably have a fight on your hands.
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Old 09-10-2007, 01:22 PM
  #122  
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Are you saying that you think all four nozzles receive the same amount of oil averaged over time? The oil delivery is pulsed and so there is a small time delay between deliveries but what I am saying is that on average, outlets #1 and 2 receive less oil than outlets #3 and 4.
Look at the picture! All the outlet gets the same oil amount. There is 180 degree (cylinder) delay between 1-3 and 2-4 outlet, but the amount is the same.

One area I have been concerned with is the pressure needed to fill the cylinders, particularly at the cold temperatures (high oil viscosity) where I live. This pump has very little capability of sucking in oil. I asked Richard about this pressure and he responded with "This pressure has not been measured, however, the oil enters the OMP right at the outflow of the oil into the oil pan. This can only be visualized on the actual hard ware, since a real picture of it does not axist to my knowlege". I may eventually attempt to measure this pressure and do some bench testing at different temperatures to see how oil flow is affected.
I think for the reason of the cold oil flow the 0w-xx oil is very important in the Renesis, and better if the xx=20 or 30. ..and I would like to know how much is the importance of the original oil pressure in the cylinder's oil filling? It is the non answered question, why I did not ordered the OMP adapter until now.
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Old 09-10-2007, 02:55 PM
  #123  
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Originally Posted by ayrton012 View Post
Look at the picture! All the outlet gets the same oil amount. There is 180 degree (cylinder) delay between 1-3 and 2-4 outlet, but the amount is the same.
Well the first problem we have here is that there is a misidentification of outlets. Here's how I identified them in my recent post --- "Look at the outlets straight on with the end cap region (spring chamber) to the right. Call the top left outlet #1 and count going counterclockwise, so the top right outlet become outlet #4". So:
my #1 is your #4
my #2 is your #2
my #3 is your #1
my #4 is your #3
Ok forget my convention, we'll use yours since you have them nicely identified in a picture. We agree on which holes are inlet and which are outlet in the cylinders.

Now look at the pistons that fit inside the cylinders (from your earlier pictures). There is a small and large piston, each with a small and large diameter portion, so there are four diameters in total. Let's identify these as:
SPSD - Small Piston Small Diameter
SPBD - Small Piston Big Diameter
BPSD - Big Piston Small Diameter
BPBD - Big Piston Big Diameter

Notice that the outlet of the cylinders that connect to outlets 1 and 3 are fed only from the big diameters of both pistons - SPBD and BPBD. Outlets 2 and 4 are fed by the small diameters of both pistons SPSD and BPSD. Therefore outlets 1 and 3 will always receive more oil that outlets 2 and 4.

There is not a 180 degree delay between 1-3 and 2-4 outlet. #1 and #2 are fed at the same time but separately, #1 with the small diameter of both pistons, and #2 with the large diameter of both pistons. After 180 degrees of cylinder rotation, #3 and #4 are separately fed, #4 with the small diameter of both pistons, and #3 with the large diameter of both pistons.
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Old 09-10-2007, 05:05 PM
  #124  
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Mr Ploppity (great name)- having run without the adaptor for 21/2 yrs and listened to what everyone here has said I have seen no compelling reason to fit it .
If you are concerned about seal failure - just run a little premix as added insurance . These people that go on about crankcase oil being "bad for the engine" have nothing to back that up with other than - "eeew doesn't it look dirty" .
Also there is nothing I have ever seen on here that proves that running synthetic will make our engines last any longer . How many renesis failures have been caused by worn bearings & gears ?

Last edited by Brettus; 09-10-2007 at 05:08 PM.
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Old 09-10-2007, 08:44 PM
  #125  
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My assumption that premix is a better lubricant than engine oil (synthetic or conventional) for the Renesis' side seals (not apex seals as I'd said above, thanks Delmeister)--comes from Richard Sohn:

"When engine oil is getting into the combustion chamber, it only is burning partially, leaving some unburned deposits behind. These deposits can build up and reduce engine performance. One obvious method of preventing this is to disconnect the metering pump altogether and mix two-stroke oil to the gasoline like some older two-stroke engines require. With this method it has been demonstrated that two-stroke oil is an effective lubricant and there is no build up of combustion residues. [He says "it has been demonstrated", but has it?] The Metering Pump Adapter...takes the solution one step further in allowing to still using the stock metering pump but supply it with two-stroke oil."

The FAQ makes it clear that "occasional aggressive driving is good...it helps prevent carbon buildup in the engine." This "carbon buildup" must be the "unburned deposits" Sohn claims can be prevented with his adapter. So why wouldn't you use it? It does make owning an RX-8 appear too complicated--thus Mazda wouldn't build them this way--but it seems to me it only requires extra effort on the front end. And the rest is all upside. Anyway, I'm not trying to sell you guys on this product. (If anything I'm trying to sell myself on an 8.) Rather, i'm looking for evidence to support Richard Sohn's claims. Is there any out there?

What I meant about "enjoying the extended oil change interval of synthetic oil" was that with the adapter the condition of the oil in the crankcase will no longer affect the lubrication of the side seals. So you can increase your oil change interval without compromising this important (and apparently sensitive) seal.
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