OMP-Pre-mix mod Write-up
07-04-03, 12:06 AM
#101
Lives on the Forum
Originally posted by Aaron Cake
That's the problem with this (and many other) mods. People do them without thinking of all the consequences. There is so much misinformation and conjecture floating around that it is very difficult for anyone to make an informed decision. Witness all the 5th and 6th port misunderstandings, etc.
That's the problem with this (and many other) mods. People do them without thinking of all the consequences. There is so much misinformation and conjecture floating around that it is very difficult for anyone to make an informed decision. Witness all the 5th and 6th port misunderstandings, etc.
Exactly. Since there is such a small market, and since the metering oil system has been proven over 16 years, there has been very little actual scientific research done with regards to premix. Getting 6 new engines and running them in simulation is no small task. Could easily cost a million dollars when all is said and done.
It's good that you pointed out the need for brand new engines. This was something I was trying to stress. Taking a bunch of used engines is pointless, because all have seen different lives and are operating in totally different tolerances. This is a point that many people who like to "prove" the superiority of premix seem to miss.
Many of the venders specifically avoid things like the forum. For good reason too. One thing is that there are very few venders with as much experience as Atkins. Mazdatrix, as well as Mazdaspeed and maybe Rotary Performance and Racing Beat. I know I'm forgetting many, but the point is valid. It is only those who have building several engines a day for 25 years that can truely offer unquestionable evidence as to the effectiveness of premix.
Just another thing to throw out: many of the rotary aviation (ties in with Atkins) guys/gals who constantly run at high RPM are still using the MOP system.
The idea is that the oil spreads accross the seal due to rotating force. Put a drop of oil on a piece of clear plastic, then use another piece to mimic the apex seal. You will see how the oil spreads.
Many don't. They hear "oil injection" and think in terms of pressurized fuel injection. The meterign pump is just that: metering. The oil to the "injectors" (should be called "dribblers") is delivered under very little pressure.
Sorry, I wasen't clear. It certainly does lubricate everything, but I was trying to stress how the metering oil system puts the oil exactly where it is needed: on the apex seals.
Well, it's just just believed, that's what happens. 
But the major difference is that two stroke oil is used to lubricate bearings in 2 stroke engines, not combustion surfaces. Therefore, it is designed to burn completely, thus not leaving a film like motor oil does. Great for 2 strokes, bad for rotaries which require the actual combustion surface lubricated.
But the major difference is that two stroke oil is used to lubricate bearings in 2 stroke engines, not combustion surfaces. Therefore, it is designed to burn completely, thus not leaving a film like motor oil does. Great for 2 strokes, bad for rotaries which require the actual combustion surface lubricated.
Two stroke oil is not designed for any fuel injection either. Or more accurately, the fuel injectors are not designed to inject oil as well. Both of our points are very valid. Remember that Mazda designed the metering oil system for convenience as well as reliability. We can't expect the average owner to keep a seperated resevoir of two stroke oil full...And think of the bad PR...
Or more accurately, the fuel injectors are not designed to inject oil as well. Both of our points are very valid. Remember that Mazda designed the metering oil system for convenience as well as reliability. We can't expect the average owner to keep a seperated resevoir of two stroke oil full...And think of the bad PR...
I was saying that the stock system pukes out at high RPM, not that premix is better. Premix is currently the only option for running constant high RPMs. The choice is either to get poor lubrication with the stock MOP, or go premix. Personally, I would just bore out the stock oil dribblers and replace the MOP with a higher capacity unit (bore out the cylinder and install a larger piston).
Good idea, but this is not a scientific test. We need a much larger number of engines then 2, and we need to start with known good units and use them in a controlled environment as they would see on the street.
This is exactly correct. Always beating on the engine will prevnt carbon from forming as much as it does on a regular, easily driven street engine.
But the carbon is not what ruins the seals. Carbon buildup is perfectly normal. Take apart any high mileage engine and you will find loads of carbon (I myself have 1.5MM of carbon on Tina's rotors).
Actually, by it's nature I would figure that 2 stroke doesn't leave a film. It is designed to burn easily and cleanly. Motor oil, on the other hand, is designed to stand up to major heat and resist breakdown. Therefore, it should form a superior film.
Nope. Carbon is a normal byproduct of burning gasoline. It's completely normal to build up carbon in any street engine (piston or rotary).
I will throw a wrench into your observations: the 12A and all other carb'ed rotaries had two oil injection lines that would inject oil directly into the venturi so it would be atomized with the fuel. Mazda abandoned this system as they went to fuel injection.
Remember that the 2nd gen 13B has 4 oil injectors (dribblers): two apply oil to the apex seals directly, two into the intake airstream. You are getting the best of both worlds: oil in the air/fuel mixture, and oil onto the apex seal. Premix accomplishes only one of those.
If something burns cleaner, it must burn more easily.
As far as premix getting onto the apex seal, how does it do this? Remember that the apex seal is designed to seal. If it seals, then there is no way for premix to migrate onto it's sealing surface. The only the sealing surface can be lubricated is with the oil film already on the housing (or via the oil dribbler). If you compromise the film on the housing (by running premix, running too rich, etc.) then the sealing surface of the apex seal is never lubricated.
I thought oil raised the octane rating? Remember that ocatane is a measure of resistance to detonation/preignition. Would not mixing oil make it more difficult to burn the gasoline, thus artificially raising octane rating?
Also, a 2 cycle bike engine is a completely different environment then a turbocharged or N/A rotary.
We can't compare like this. We need to compare engines in controlled environments by properly using the scientific method. Too many variables in real life.
Oh, I have no doubt that it will burn cleaner. But that means that it burns easier. And it's not actually oil deposits we are seeing when we disassemble an engine. The deposits we see (carbon) is caused by incomplete combustion of gasoline.
I wonder: what has more impurities, the fuel that you spray in via the injectors, or the oil in the crankcase? Probably the oil for sure, though judging by the carbon on the rotors, maybe not...
My fingers are quite tired from typing, so I think I'll end there...But to answer the question about blocking the passage: there's no reason you can't do it. Removing the driven gear from the front cover will be pain, but it certainly can be done.
-Ted
07-04-03, 12:17 AM
#102
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As far as premix getting onto the apex seal, how does it do this? Remember that the apex seal is designed to seal. If it seals, then there is no way for premix to migrate onto it's sealing surface. The only the sealing surface can be lubricated is with the oil film already on the housing (or via the oil dribbler). If you compromise the film on the housing (by running premix, running too rich, etc.) then the sealing surface of the apex seal is never lubricated.
07-04-03, 12:27 AM
#105
Lives on the Forum
Originally posted by Aaron Cake
This is a major part of my argument against premix. Two stroke oil is not designed to lubricate combustion surfaces. In the two stroke piston engine, the premixed oil lubricates crankshaft and rod bearings, as well as the cylinder walls on the non combustion side of the piston. All the oil that ends up on the combustion side of the piston is burnt off during the combustion process. Thus, the oil is advertised as "clean burning". Although if you pull the spark plug on a two stroke engine, you will see how much carbon has built up. Also take a look inside the (probably half clogged) muffler. Back in my lawnmower repair days, 75% of two-stroke mower problems were caused by clogged mufflers and/or plugs. Though this might be the owner's fault for mixing in too much oil...
This is a major part of my argument against premix. Two stroke oil is not designed to lubricate combustion surfaces. In the two stroke piston engine, the premixed oil lubricates crankshaft and rod bearings, as well as the cylinder walls on the non combustion side of the piston. All the oil that ends up on the combustion side of the piston is burnt off during the combustion process. Thus, the oil is advertised as "clean burning". Although if you pull the spark plug on a two stroke engine, you will see how much carbon has built up. Also take a look inside the (probably half clogged) muffler. Back in my lawnmower repair days, 75% of two-stroke mower problems were caused by clogged mufflers and/or plugs. Though this might be the owner's fault for mixing in too much oil...
So you're implying that engine oil lubricates past the combustion cycle?
Hmm, I doubt it. The "contaminates" are mostly chemical, not "solid" and would be so small that they would be trapped in the pores of the housing anyway. This is probably not a great issue. However, over time these contaminates could build up and clog metering oil nozzles. Many engines have at least one clogged nozzle.
Not really. At 3000 RPM, the rotors are moving at 1000 RPM, which is 16 revolutions per second. The apex seal is hitting that oil droplet with considerable force, and I'd imagine that it splatters almost instantly accross both the seal and the housing. Sounds like an excellant lubrication strategy to me.
Premix, on the other hand, remains mostly in the "cloud" of vapourized fuel and air. Since the premix droplets are so small, they remain suspended and simply burnt with the combustion process. This might be another disadvantage of premix. The droplets are probably way to small to properly coat the housing. But the only way to prove this would be high speed video...
Again, carbon buildup is not due to oil, it is due to the normal combustion characteristics of the carbon and hydrogen based gasoline.
As I mentioned, comparing random used housings is almost pointless. Yours might be scuffed up, but someone else's might not. In fact, the housings from Tina's engine (250,000 on the clock) are nearly perfect save for the standard corner-of-the-apex mark. I could look at the 10 pairs of housings I have on hand and find that 50% of them are scuffed and scratched, the rest are pretty shiny. We cannot compare engines unless they are broken in and run in labratory conditions.
I should also mention that the cylinders in a piston engine are regularily grooved and scuffed on the oil side. It's part of normal wear inside of any machine.
The point I'm trying to make is that this isn't true. Premix will lubricate the face of the rotor, and the housing (a little), but will miss the apex seal for reasons I have already explained. Any lubrication on the apex seal would be from oil that has remained on the housings, but most of this is burnt off at every combustion cycle.
That gasoline we are burning leaves behind alot more deposits then a little oil does. And since 4 stroke oil is of much thicker viscosity, and distinctly not designed to burn, it forms a thicker film that actually survives the combustion cycle.
But wait...if the oil is "clean burning", then how can it leave behind a film? See the comments above about how a two stroke engine is lubricated.
We have also ignored viscosity for the most part. Two stroke, especially after it has been diluted by fuel and atomized, is MUCH thinner then 4 stroke oil. With the high temps of the rotary, it stands to reason that it burns much easier and much more completely then in any two stroke piston engine.
[Four stroke oil, on the other hand, lands as a huge drop directly on the apex seal, where very little of that combustion heat is encountered. There is also a certain amount injected into the airstream. The oil injected into the airstream is vapourized by the fast moving air, meaning that it is in larger droplets and therefore has a much greater lubricating capacity when spread over a surface.
Just something to mention as well: maybe I don't want my oil to completely burn up. We still have an exhaust stroke to go through, you know...
Carbon buildup is not caused by incomplete combustion of oil delivered though the metering oil system. That will be the fifth time I have said it.
That will be the fifth time I have said it.
If Mazda had built the metering oil system to premix oil before the injectors, they would have injected the oil AFTER the filter and provided fuel injectors that are specifically designed to be compatible with the larger oil molecules.
This has been around for about 4 years now, and I have mixed feelings about it. On one hand, you have the advantages of the stock oil metering system. On the other hand, you have two stroke oil that has neglegable lubricating (in my opinion anyway) qualities when used inside a rotary working chamber. If anything, I would install this adapter and then run clean 4 stroke oil through it.
The problem is not so much that the car cannot reach 7K (because it can). The problem is that owners of auto RX-7s tend not to drive them hard. Combine this with the short-trip and stop-and-go driving, and you have major carbon buildup. Which, again, has nothing to do with the metering oil pump.
Just one other thing: many people seem to think that higher octane fuel is somehow better for their N/A car. Could this be a major reason for carbon buildup? Probably...
One final thought I'd like to leave before I stop this waste of my time debate...
The R26B on the famed LeMans winning Renown racer featured pre-mix fuel with no oil injection.  The failed 4-rotor AutoExe racer in the 2002 LeMan was running pre-mix with no oil injection.  Ask yourself why these vehicles running in one of the most famous endurance races on this earth do not inject 4-stroke engine oil into the combustion chambers...
-Ted
07-04-03, 05:42 PM
#108
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Originally posted by Aaron Cake
Aw man, now I have to write a really long reply...
Aw man, now I have to write a really long reply...
i thought you were gonna blow your top after reading all that..
good to see that this thread wont be reduced to flames..
07-05-03, 11:38 AM
#110
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Originally posted by rxrotary2_7
Ted ALWAYS has excelent points! i love reading his responses.
Ted ALWAYS has excelent points! i love reading his responses.
I don't know where Ted has been as of late (haven't seen many posts by him recently) but I'd hate to see a top poster like him fade away..
07-05-03, 12:58 PM
#111
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I read some of the posting and heard some good points thrown around. Here is what I have to say:
Injecting oil into a chamber with an oil injector and injecting oil through a fuel injector are going to create different results.
Ted made a lots of good points, but this was his worst
How can you compare a completely modded engine to the Mazda orginal design. I bet the 4-rotor engine is rebuilt and inspected over and over again. Mazda's Rx-7's Fbs, FCs, FDs and every other rotary engine was design by highly qualified engineers. Just because you been around rotaries for a while and you went through the forum and nit picked everyones errors mean your ideas are fully corrected.
Here is my point. OIL has more fuctions than what people think.
Cooling, lubrication, preventing rust, postive sealing, and more. The FC has 4 oil injectors and the FD has 2 due to the fact that the FD housings are treated to resist wear than the FC housings. The FC housing will see wear faster than the FC. BTW: The 2 injectors are still injected into the chambers. So 2 less from the intake. Big DEAL.
Pre-mix, whats going to happen when some people do this mod and hit Fuel cut off. NO FUEL + NO OIL + HIGH BOOST = ****. The FD when under boost injects little to no oil into the chamber. More oil is feed through the internals though. When there is no boost, more oil is injected in the chamber. That is why before you shut off your car you should let it idle for a while.
BTW: If Pre-mix is so superior and the design of the 13b engine is old technology, why is the rensis using oil injectors.
Don't get me wrong I am not saying Pre-mix is bad. I am just say I have not seen a mod that increase the reliablity of the rotary from mazda's orginal design. Thus the 13b N/a being very reliable IMO.
TED you can flame every one in the thread, but I don't seeing this modification reducing the wear of the internal combusting engine. When it comes to boosting at 10psi, pre-mix is great because now you are getting that extra lubrication. When not boosting under heavy loads, That injector is doing its job.
- Orlando
Injecting oil into a chamber with an oil injector and injecting oil through a fuel injector are going to create different results.
Ted made a lots of good points, but this was his worst
The R26B on the famed LeMans winning Renown racer featured pre-mix fuel with no oil injection. The failed 4-rotor AutoExe racer in the 2002 LeMan was running pre-mix with no oil injection. Ask yourself why these vehicles running in one of the most famous endurance races on this earth do not inject 4-stroke engine oil into the combustion chambers...
Here is my point. OIL has more fuctions than what people think.
Cooling, lubrication, preventing rust, postive sealing, and more. The FC has 4 oil injectors and the FD has 2 due to the fact that the FD housings are treated to resist wear than the FC housings. The FC housing will see wear faster than the FC. BTW: The 2 injectors are still injected into the chambers. So 2 less from the intake. Big DEAL.
Pre-mix, whats going to happen when some people do this mod and hit Fuel cut off. NO FUEL + NO OIL + HIGH BOOST = ****. The FD when under boost injects little to no oil into the chamber. More oil is feed through the internals though. When there is no boost, more oil is injected in the chamber. That is why before you shut off your car you should let it idle for a while.
BTW: If Pre-mix is so superior and the design of the 13b engine is old technology, why is the rensis using oil injectors.
Don't get me wrong I am not saying Pre-mix is bad. I am just say I have not seen a mod that increase the reliablity of the rotary from mazda's orginal design. Thus the 13b N/a being very reliable IMO.
TED you can flame every one in the thread, but I don't seeing this modification reducing the wear of the internal combusting engine. When it comes to boosting at 10psi, pre-mix is great because now you are getting that extra lubrication. When not boosting under heavy loads, That injector is doing its job.
- Orlando
07-05-03, 01:27 PM
#112
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Originally posted by ERAUMAZDA
How can you compare a completely modded engine to the Mazda orginal design.
How can you compare a completely modded engine to the Mazda orginal design.
let me stop you here and say thats an excellent comparison. the 4-rotor was designed for racing and modification, and NOT designed under the common ideals of a daily driver (what im getting at is, the 4rotor wasnt designed to meet the laziness-i mean convienience of NOT having to premix fuel.)
I bet the 4-rotor engine is rebuilt and inspected over and over again.
probably, which suggests why they decided to use premix. once they saw premix not lubricating properly, they would have gone back to MOP. and, they havent.
Mazda's Rx-7's Fbs, FCs, FDs and every other rotary engine was design by highly qualified engineers.
so, this would include the 4-rotor.. right? what are you getting at?
Cooling, lubrication, preventing rust, postive sealing, and more. The FC has 4 oil injectors and the FD has 2 due to the fact that the FD housings are treated to resist wear than the FC housings.
The FC housing will see wear faster than the FC.
Pre-mix, whats going to happen when some people do this mod and hit Fuel cut off. NO FUEL + NO OIL + HIGH BOOST = ****.
this has been mentioned numberous times throughout the thread.
That is why before you shut off your car you should let it idle for a while.
no, actually you should let it idle to let it cool off, and let the oil flow through the turbo to cool off the turbo. thats the function of a turbo timer.
BTW: If Pre-mix is so superior and the design of the 13b engine is old technology, why is the rensis using oil injectors.
Ted already mentioned "why would a customer want to keep up with the premix? if he or she forgets to add the oil, the engine is garbage."
seems logical enough to me.
not trying to flame, just trying to further the debate, Orlando.
07-05-03, 01:30 PM
#114
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Originally posted by Ezekiel702
So what is the point in this mod and why do it? Just wondering...I dont know much
So what is the point in this mod and why do it? Just wondering...I dont know much
07-05-03, 01:48 PM
#115
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lol sorry I didn't read all 113 posts I tried to get a overall understanding but MOST OF THE POSTS ARE OPINIONS because I'm sure most all of you guys know what the hell this mod is so maybe instead of being a smart *** you could just type the 2 senteneces and tell me what it does. You don't need to reexplain how to do it...
07-05-03, 01:49 PM
#116
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Yeah Black13B, I did mean the FC housing surface will see wear faster than the FD housing under the same conditions.
The 4 rotor wasn't design by a mulit-million dollar company that made everything from scratch. It would be pointless since the 4-rotor is not a production engine.
Turbo or not the engine should be idle for a while. This allows proper cooling of parts and allows oil to proper coat moving parts...its almost like pre-lub before the next start up. Also, turbo are not a car should be left to idle on start up. This can add more life to any combustion engine.
- Orlando
The 4 rotor wasn't design by a mulit-million dollar company that made everything from scratch. It would be pointless since the 4-rotor is not a production engine.
Turbo or not the engine should be idle for a while. This allows proper cooling of parts and allows oil to proper coat moving parts...its almost like pre-lub before the next start up. Also, turbo are not a car should be left to idle on start up. This can add more life to any combustion engine.
- Orlando
07-05-03, 01:52 PM
#117
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Originally posted by Ezekiel702
lol sorry I didn't read all 113 posts I tried to get a overall understanding but MOST OF THE POSTS ARE OPINIONS because I'm sure most all of you guys know what the hell this mod is so maybe instead of being a smart *** you could just type the 2 senteneces and tell me what it does. You don't need to reexplain how to do it...
lol sorry I didn't read all 113 posts I tried to get a overall understanding but MOST OF THE POSTS ARE OPINIONS because I'm sure most all of you guys know what the hell this mod is so maybe instead of being a smart *** you could just type the 2 senteneces and tell me what it does. You don't need to reexplain how to do it...
07-05-03, 01:53 PM
#118
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Originally posted by Ezekiel702
I'm sure most all of you guys know what the hell this mod is so maybe instead of being a smart *** you could just type the 2 senteneces and tell me what it does.
I'm sure most all of you guys know what the hell this mod is so maybe instead of being a smart *** you could just type the 2 senteneces and tell me what it does.
rotary engines need lubrication at the apex seals (among other places). how you gonna do that? mazda's stock MOP drops oil right at the tip of the seal which in turn lubricates it.
this system draws off of the 4 stroke oil in the oil pan. This results in burning off the oil, and your oil gets low (youll notice its down a quart or so at oil change time).
the argument is about if the MOP system is efficient and an adequate lubricator.
premix removes the MOP system, and injects the lubrication via the air/fuel, rather than having a different system for it.
im not going into any more detail, because i KNOW its all been posted, and im just regurgitating.
07-05-03, 04:55 PM
#121
Former Moderator. RIP Icemark.
2 points
#1 The 4 rotor Ted mentions, doesn't use a MOP simple for the KISS reason. One less part to fail in a race designed vehicle that didn't have to travel 100K miles before rebuild.
#2 The oil injectors (or dribblers as mentioned above) on the 13BT-REW have higher flow both through the MOP and the orifices than the ones found in the 13B in the FC.
#1 The 4 rotor Ted mentions, doesn't use a MOP simple for the KISS reason. One less part to fail in a race designed vehicle that didn't have to travel 100K miles before rebuild.
#2 The oil injectors (or dribblers as mentioned above) on the 13BT-REW have higher flow both through the MOP and the orifices than the ones found in the 13B in the FC.
07-14-03, 10:46 PM
#124
Jesus is the Messiah
Some interesting points that have come up, and are still kinda in the air about this thread:
1) The true cause of the carbon-biuld up, is it only the MOP, or just regular combustion prossess? Does revving the engine up really help blast the carbon out, to the point of preventing carbon-lock?
2) Premix, with the engines named here, (even the four rotor race engines) aparently does work on its own, but is it really nessisary? Many times the MOP has been claimed to be a reliable unit. (Specially on the S5, aparently) I will, however, have to add periodic checking of the MOP injectors to my tune up list.
1) The true cause of the carbon-biuld up, is it only the MOP, or just regular combustion prossess? Does revving the engine up really help blast the carbon out, to the point of preventing carbon-lock?
2) Premix, with the engines named here, (even the four rotor race engines) aparently does work on its own, but is it really nessisary? Many times the MOP has been claimed to be a reliable unit. (Specially on the S5, aparently) I will, however, have to add periodic checking of the MOP injectors to my tune up list.
07-14-03, 11:00 PM
#125
Originally posted by Tofuball
Some interesting points that have come up, and are still kinda in the air about this thread:
1) The true cause of the carbon-biuld up, is it only the MOP, or just regular combustion prossess? Does revving the engine up really help blast the carbon out, to the point of preventing carbon-lock?
2) Premix, with the engines named here, (even the four rotor race engines) aparently does work on its own, but is it really nessisary? Many times the MOP has been claimed to be a reliable unit. (Specially on the S5, aparently) I will, however, have to add periodic checking of the MOP injectors to my tune up list.
Some interesting points that have come up, and are still kinda in the air about this thread:
1) The true cause of the carbon-biuld up, is it only the MOP, or just regular combustion prossess? Does revving the engine up really help blast the carbon out, to the point of preventing carbon-lock?
2) Premix, with the engines named here, (even the four rotor race engines) aparently does work on its own, but is it really nessisary? Many times the MOP has been claimed to be a reliable unit. (Specially on the S5, aparently) I will, however, have to add periodic checking of the MOP injectors to my tune up list.
1) Carbon build up is comming from BOTH fuel I.E. gasoline and four stroke oil.
2) Pre-mix is NOT necessary. But what got ME to switch is three main points: a) The reliability of the MOP and its injectors and lines. There are just about no ways to know if the S4 pump is working or not unless you check the lines for oil movement and test the injectors which involves removing the lines which will probably break costing you about 100 dollars to replace the set more if you need to buy an injector. b) The issue of the ability of four stroke oil to properly burn and not leave too much bad stuff behind(chemical or otherwise) c) The MOST SIMPLE reason: LOOK at your oil when you change it after 2-3k miles. I don't like that on the inside of my engine.
That last one is the BIG reason for me.
Santiago
PS- I too wait for Aaron's respond to Ted.