Havoc

meh, with that argument you may as well run 3 fuel pumps just in case 2 fail.

7 n 7

When the OMP fails or when you realize engine oil is not meant to be burned in the combustion process. Very simple.

fcdrifter13

If you meant this like i read it please sell your 7 to someone else right now.

7 n 7

How do you figure and why would you say that? Do you believe the OMP and motor oil are the absolute best ways to lubricate the rotors and housings?

The original question was, "when do you need to premix?". My response was a bit sarcastic.

I am pro pre-mixing by the way.

fcdrifter13

God I thought you meant that you were not running any kind of lube in that ****, i just about **** a brick.

7 n 7

heh. Oh hell no . I am pre mixing at full strength but have been procrastinating on disabling the OMP for the past month or so since I got the motor in the car. Probably gonna do it this weekend.

7 n 7

I still don't understand any downside to pre-mixing other than laziness or forgetfullness. The whole off-throttle/decell thing is a non-issue.

Slow Rotor

Well for those that are premix'in to run synthetic oils this is the reply i got from my engine builder when i sent em an email if they think its worth doing

Chris, I would still reccomend to use a mineral oil such as penrite HPR40 we find it works best for bearing protection and doesnt pump out like thinner oils can on bigger boost. I think you will find most synthetic oils are quiet thin oils. Its your car and your engine I can only tell you what we have found to be the best for us. With pre mixing use a ratio of between 100:1 and 200:1 depending on where exhaust smoke begins.The unbreakable seals love the extra lubrication.

Fozzybeardude

Built the car this year, first RX7 I've ever owned. Lots of research completed and different opinions heard before my season started.

Almost all synthetic motor oils will not burn clean enough to keep from causing long term issues in the cumbustion chambers. I purchased 2 cases of Idemitsu Rotary Premix oil from Mazdatrix. I mix 1 once per gallon and have continued to use non synthetic in the engine. 8 races in the books on fresh motor w/ 4 left this year and plugs are clean, little to no carbon build up in exhaust.

I'm running an S5 and decided I would premix to avoid any dnf's due to possible omp failure. Faiure isn't likely but I had the block off plate and ya know, an ounce of prevention is worth a pound of cure.

ericgrau

iTrader: (1)

8mL 2 stroke per liter is 1:128. That's if you disable the OMP. With the OMP enabled you can add 4mL per liter for a little extra lubrication. Remeber that if you disable your OMP and ever forget to premix, you'll be in trouble. It seems your car is running fine. If you really want to be safe, why not keep your OMP and add 4mL per liter (or maybe more)? Or even 8mL per liter with your OMP enabled. That's a bit rich but it shouldn't cause any serious problems. Maybe a little smoking and something else (loss of fuel economy? somewhat earlier spark plug fouling?) if I remember correctly.

I noticed you have an S5 (1989-1992). The electronic OMPs on those do tend to be less reliable, whereas the mechanical ones rarely fail. You could just replace it with a brand new one to be safe if you're really worried, or jimmy up a mechanical S4 OMP like someone mentioned (not just a simple swap). In the meantime I'd just add the 4mL 2 stroke per liter, if anything, and not worry about it.

SpideyFan6010

That is the thing I heard that these Electrical OMP go out easy and are ify. I would be a lot more at ease knowing it is a mechanical OMP. Yes Premixing is a bitch.

Slow Rotor

Well it was quite a scary site, when i removed the UIM, there was a fair bit of oil, as all 4 of the lines that go to the top of the injectors were split

RotaryWeaponSE7EN

iTrader: (6)

I dont see hows it hard to carry 12-14oz of premix in your car and add it when you fill up. Been doing it for atleast 4 years with my GXL.

Slow Rotor

I have decided it's not hard too at all, after researching properly about the argument of premix vs OMP, i have removed the OMP. It also makes the engine bay look cleaner without all the lines there. But it's up to the car owner really. I carry 5L of coolant and engine oil in my car anyway so the small bottle of premix isn't a problem

7 n 7

I have yet to disable the OMP but have been getting ready by running 100:1 and have yet to see any smoke. Fuel mileage seems ok at 17.5 mpg.

I was on 1/4 tank today and had run 250miles since last fill-up and put in 14.29g to fill up. 90% of that driving was all stop and go city driving. Is 17.5mpg good for city driving in a 91 vert auto?

By the way, who determined 100:1 was optimal with omp disabled?

My main reason to pre-mix is not because I'm worried about the omp failing. It's because I have seen the inside of a few rotaries with less than 100k and was astonished by how much caked up gunk was on the rotors.

Slow Rotor

Well apparently 128:1 is optimum, but my engine builder told me anywhere between 100:1 and 200:1 is fine, he said that the cars running the higher boost run the bit extra oil

RotaryWeaponSE7EN

iTrader: (6)

Slow you sound like me, I got 5L of antifreeze, Half gallon of Lucas stuff I use and 2 gallons of water. Also got a fullsize spare sitting in the back, cables, extra lugnuts and a glove for my right hand. That greddy/trust shifter get really hot under the sun.

7 n 7

Ok, still no real explanation for how the 100:1 ratio came to be. In the eighties, my 2 stoke dirtbikes and 3 wheelers had a manufacturers suggestion to run 20:1 and nowadays, weedeaters and such range from 32:1 to 50:1 and I realize the difference between the 2stroke piston and the rotary is that the rotor is suspended and carried by the E-shaft and stationary gears and doesn't require as much extra oil as the 2stroke piston that is slapping against it's bore.

So, the rotor itself doesn't require the lube that a 2 stroke piston does because it's just all the spring loaded seals that require lube whereas a 2stroke piston skirt needed the extra lube.

Since my 91 vert doesn't smoke using 100:1 and a working OMP, would 80or60:1 be out of the question for a premix with no OMP? Who decided 100:1 was optimal for long term use? Meaning, 100-200k miles.

7 n 7

Was this a too unorthodox a set of questions or should I use the search feature for the same old responses?

Slow Rotor

Well you should have used the search feature before you asked lol. I figure someone alot smarter than me worked out the ratios so i'm not going to doubt them.

Fozzybeardude

Once you start premixing, it's important to remember that more oil isn't always going to be better. When the OMP is still active and you aren't premixing, the injection is providing the correct amount of fuel that is needed at any given time.

Once you start premixing, now what used to be gas only flowing throught the injection is now a ratio of fuel and oil and if you add too much oil, that equals less fuel getting to the engine which can cause a lean condition and lead to lots of trouble. 2 stroke guys know that the less oil you mix into the fuel the more power you are able make but it's a balance of having enough oil to lube the engine while having enough fuel so the engine doesn't lean out.

If was driving an RX7 on the street, I wouldn't change the factory oiling system. If you have a mechanical metering pump it's very reliable, if you have the electronic metering pump, Mazda designed a safe mode in the event of a failure.

7 n 7

I didn't say I necessarily doubted the ratio, I was just curious where it came from. What did the factory do with the 787? Just looking for an answer here, I know there is a huge difference between a high rpm race engine that is rebuilt or replaced after every race and a street motor.

Also, most would realize from my wording, that I did search and didn't find the answer to my particular question.

I, on the other hand, am not willing to blindly trust people who are supposedly smarter than me.

The whole search **** thing tends to get old. If every possible question had been asked and sufficiently answered, the forum would die because every single person could answer any imaginable question just by searching and there would be no further discussion.

Mr.FC3s

In my S4 GXL I just made sure that my OMP was feed with a nice supply of oil and i did add maybe 5oz every fill up of 2stroke. and a bottle of seafoam every 3rd fill up. Some one told me using that mystery oil everynow and then was good for the OMP. idk never tried

ilia

iTrader: (4)

I'm also curious as to how the ratio was determined.

I run .5oz/gallon of fuel, as I still have my mechanical OMP.

I do it for two reasons:

First, the car doesn't seem to consume enough engine oil. It uses some, but not as much as it should 1qt/1000miles.

Second, in the event of an oiling failure, premix will still enter the engine. I lost oil cooler lines on this engine last year, and lost quite a bit of oil pressure before I turned it off (it was as low as 18psi at idle by the time I shut it off). I was premixing, and the motor is fine to this day, with healthy compression. I'd imagine that wouldn't be the case if I wasn't

Anyway, I like premix. It doesn't seem to hugely affect gas mileage, and I can't see how it could make anything worse. Mazda premixes their race cars, so it can't be all that bad.

ilia

iTrader: (4)

I'm also curious as to how the ratio was determined.

I run .5oz/gallon of fuel, as I still have my mechanical OMP.

I do it for two reasons:

First, the car doesn't seem to consume enough engine oil. It uses some, but not as much as it should 1qt/1000miles.

Second, in the event of an oiling failure, premix will still enter the engine. I lost oil cooler lines on this engine last year, and lost quite a bit of oil pressure before I turned it off (it was as low as 18psi at idle by the time I shut it off). I was premixing, and the motor is fine to this day, with healthy compression. I'd imagine that wouldn't be the case if I wasn't

Anyway, I like premix. It doesn't seem to hugely affect gas mileage, and I can't see how it could make anything worse. Mazda premixes their race cars, so it can't be all that bad.