Brettus

iTrader: (2)

Yes there is probably some truth in all of that but we all form our own opinions unless confronted with irefutable evidence .
The thing is that only tiny amounts of oil are injected anyway and if you do plenty of aggressive driving (like I do) , I doubt the increased carbon build up from using crankcase oil vs 100% premix oil will be an issue .

ayrton012

First of all, thanks for using my "outlet numbers".
You will see my thoughts on the attached pics as my answer to your quoted rows.

Delmeister

Those areas do not do the pumping. They are just recesses, probably to facilitate oil inlet. It is the other two surfaces that are the pistons. Those surfaces fit snugly in the cylinders, prevent leakage, and do the pumping as the cylinders are reciprocated. It is better seen in the attachment I included a while back.

Delmeister

A refreshing stand. To ask for evidence can make you an enemy of the state on this forum sometime.

mac11

iTrader: (1)

that is your own personal preference and please don't take this as trying to convince you one way or another. I would just like to add that there have been rotaries around for much, much longer than this car. This car has not been out long enough to really conclusively say what does or does not work in the long term. You may have no problems with no premix and no secondary 2-stroke injection but joe blow might have a seal failure. Was it the oil or carbon buildup in the combustion chamber? who knows? Mazda is not saying. my point being - to see what has been proven look to the rx7 guys and see what has worked there. Those have been around for quite a while and had many many more miles put on those blocks. The drivers and aftermarket for those cars have come up with many innovative solutions to extend the reliable lifespan of a rotary motor.

Delmeister

mac11--given that Mazda has been involved in the rotary longer and to an infinitely greater depth than any RX-7 guy, why do you think the company does not use separate oil injection?

dannobre

iTrader: (3)

^^ way too complicated for anyone but a true rotorhead......Most drivers i know have a hard time remembering to check ONE oil level......

mac11

iTrader: (1)

First of all, I would like to reiterate that my statement was not to try to convince anyone either way of what to do on this issue or even advocate that its a must have product. Think of me as Switzerland on the issue. I do NOT have this part fitted on my personal vehicle. My entire intention was only to say look to the rotary history for guidance - not necessarily in this instance - but in general.

But for the entertainment value I will entertain your question. Along with what danobre just posted another great answer was already posted in this thread. Adding a separate tank for injection oil would "appear" to the general public that the car was "too much hassle" or "so much extra maintenance" that it would lose favor and sales. When magazines reviewed the RX-8 and gave it rave reviews they included things like "we were disappointed in how much oil this car burns." And these were from automotive journalists who had driven the RX-7s and should have known better than to knock the engine for doing what it was designed to do. I could only imagine the drivel to spew from those pages had they had to spend ALL THAT TIME AND EFFORT topping up an auxiliary oil tank every few thousand miles.

Brettus

iTrader: (2)

fair enough - few would argue that premix is not beneficial . However the benefit of the RS adaptor is less certain .
I don't think the tiny amount of crankcase oil injected is likely to be a problem for my engine due to the way I drive - to others who baby the engine it may be .

Delmeister

I agree with you mac11, and I think that the following is a fair assumption:

Everyone is watching, and Mazda is paranoid about making this engine introduction a success.

This leads to my questioning this
Once Mazda decided to take the hit on the bad publicity relating to oil consumption, I doubt it would compromise the engine by not giving it enough oil. Because some oil is good, it doesn't necessarily follow that more is better.

I personally don't add oil. I fill to maximum, drive till the level reaches minimum (~5000 km), and then dump the oil.

mac11

iTrader: (1)

Not saying you have a bad plan but its been pretty well documented that oil consumption has been gradually leaned out since the late 80's. It probably won't matter much to most people because they won't own the car long enough or put it into the types of situations to experience a seal lubrication related failure. Heck, maybe mazda really has just been advancing their seals further and further to the point where they need this much less oil to stay in good shape. That actually wouldn't surprise me either. But you do get better sealing and compression when you have more oil. Someone who works for a mazda dealership said recently that the new electronic tool that is used for compression checks and determining if an engine gets replaced under the recall has the ability to crack open the MOP to 60 (full open). And they do this for about 5 minutes before retesting a car that has just fail the test by a slim margin before retesting. That is a hard and fast admission, by Mazda, that they know more oil will create higher compression and better sealing.

Delmeister

So what do they do about the engine if it then passes? If the engine deteriorated to the point where it just failed, the now excessive leakage will probably accelerated the rate of further deterioration.

Oil will aid in sealing and is useful for diagnostics and that is about all that Mazda is admitting. But what are they admitting to for continuous operation? Do they tell you to get more oil in there?

mac11

iTrader: (1)

That is something you would have to take up with Mazda. I have no answers. Only passing along what I know.

StealthTL

iTrader: (1)

None the less, an excellent piece of information, Mac!

S

Delmeister

Shortly after I suggested there was an unequal distribution of oil delivered to the nozzles, I discovered a serious oversight in my reasoning. I now have to say that:

What I overlooked was that when the vacuum is being created by the big diameter portion of either piston, the small diameter portion is moving into the space and reducing the amount of space available for drawing in oil. The volume created depends on the difference in the cross-sectional area of the two diameters. I only recently got an opportunity to measure the diameters, and as it turns out, the cross-sectional area of the large diameters of both pistons is twice that of the small diameters, so the difference is just the cross-sectional areas of the small diameter. Here's the proof:

Small Piston
Small Diameter - 1.82 mm. Cross-sectional area = (Pi/4)*D*D = 2.60 square mm.
Big Diameter - 2.58 mm. Area = 5.23 square mm.
Difference in cross-sectional areas = 5.23 - 2.60 = 2.63 square mm (~ to the small diameter cross section within measurement accuracy)

Big Piston
Small Diameter - 3.84 mm. Area = 11.58 square mm.
Big Diameter - 5.43 mm. Area = 23.16 square mm.
Difference in cross-sectional areas = 11.58 square mm.

TrochoidMagic

wait,wait,wait. sorry for the noob needing more info here. so this adapter modification lets you "bypass" engine oil to be used in the omp? so how does it work again exactly?

long thread...but from what i think, it uses the omp motor and uses another housing as a source for the 2 stroke lube(windshield washer reservoir). so does this mean that the omp motor will be lubed itself from the additive(2 stroke fluid) from the windshield washer reservoir? therefore cancelling any drain from the crankcase oil for oil consumption?

really nice if anyone can help again with an explanation as i would be interested in using this mod. but just unsure if the omp motor will be running on engine oil or the 2 stroke oil. and if it is the 2 stroke oil...will the omp be reliable then???

thanks

TrochoidMagic

btw, new rx-8 owner...still under break-in miles. noob to this forum. 2nd rotary car, but noob to the new systems.

if i'm asking weird basic questions, its because i haven't even got the chance to look around and understand the new systems, yet. been a honda technician, but when it comes to rotaries, i'm stomped.

Ploppity Drown

You got it. The whole point of the adapter is to substitute premix oil for engine oil as the OMP's source. No more engine oil consumption through OMP. Doesn't completely eliminate engine oil consumption, though.

You provide the reservoir. The windshield washer reservoir is a convenient option. Unless you value the ability to wash your windows on the road. Of course, with the 8, you probably visit the gas station enough that you're never too far away from a squeegee.

Don't see why this would make the OMP itself less reliable. If anything it'd be more reliable since it's pumping cleaner oil.

ayrton012

It's great that you say the nozzle's oil volume is the same.
I would like to measure how much is the real difference between the bigger (or the little one) piston's two oil holder volume. I'm not sure that there are difference.

Delmeister

For the same stroke length, the big piston to small piston deliveries will scale according to their cross-sectional areas, i.e. 11.58/2.6 = 4.45. The question is how do the individual stroke lengths depend on stepping motor position, and how does stepping motor position depend on engine demands. I have the means of finding this out. Someday I will get around to doing it.

Delmeister

ayrton012

In attempting to measure the stroke lengths as a function of step position, I found that it took 22 revolutions of the input shaft to get two strokes of the cylinder housing the small piston, and 11 revolutions for the large (i.e. the large revolves and reciprocates twice the rate of the small). Earlier you indicated that for two strokes, it took 16 revolutions for both.

Would you please check this. Aside from operating it, could you also re-count the teeth on the gears and take a closer look at the worms. In particular look to see if one of the worms is a double thread. I would do this myself, but I still have some testing to do and don't want to disrupt things if I can help it. Thanks.

Brettus

iTrader: (2)

Seeing as you guys have delved into this quite deeply . Is there a simple way to stop the oil flow from the omp without setting off a cel ?
I want to do away with it and premix in the fuel tank .

Delmeister

So you've gone from healthy skeptic to total convert. I'm gonna have to try that pre-mix someday.

You can do this to stop the MOP from delivering oil.
Remove the end-cap plate, pull out the pistons. remove the springs, replace the pistons, re-place the springs but this time over the piston caps, replace the end-plate.

I went out to see if this could be done without removing the pump. I was able to get a screwdriver on a couple of the screws but it was difficult to turn. Removing the battery and battery box should make things much easier.

Hold the plate when removing the last screw, otherwise the springs could send the plate and pistons flying. I've done this on the bench and everything runs fine, although the springs were facing vertically and easy to reposition. On the vehicle the springs face horizontally and will be more challenging to hold in place when replacing the plate. Note that I did not check to see if the flow stopped. I only reasoned it had to.

Brettus

iTrader: (2)

thankyou for that mr meister

Keef

What kind of oil is everybody using? And the cheapest place too buy it? I've been searching online for Idemitsu oil for a while now, but they don't seem too make 2-stroke oil for this idea...

Can somebody point me towards a good oil, because I thought I would be buying Idemistu...