Regret removing the OMP?
 

I'm about rebuild my engine and debating on keeping my omp or removing it. It currently works fine and haven't seen too many post or hear about too many ppl complaining about them failing.

Those that have removed their omp do u wish you kept it?

removed mine with my second engine and went with premix... never looked back. just one less part in the engine bay.

Why change it if it aint broken ?

The lines can break fairly easily if I'm not mistaken, and by the time you notice the puddle of oil the damage will most likely be done already...

I went premix several years ago and am fine with it. I would only want to keep the omp if I were running a relatively stock car AND I modified it to pull oil from a separate tank of dedicated premix. I'm not trying to inject used motor oil into the combustion chamber :lol:

its like removing emissions parts in cars that are in states that dont require emissions testing. yea the parts work but theyre not 100% required and the car will function just the same without them...

plenty of people run omp-less and premix with no problem, some do both... its all preference really. i deleted mine when i figured out i could and how premixing with 2 stroke is more beneficial than using the oil from the pan.

keep it if you want to keep it or delete it. keep in mind if you delete it then youre going to have to go power fc or some other standalone. without the omp hooked up you will go into limp mode and thats no good for anyone....

there's nothing wrong with premixing and using the OMP, mazda put the OMP there for a reason, you should use it if it's not broken.

Yeah, because Mazda recognized that the average motorist is a fucking idiot when it comes to mechanics and maintenance, and if they tried to sell vehicles without a no-thoughts-needed lubrication system then they would have a masive amount of destroyed engines on their hands :rofl:

At no point is injecting dirty motor oil into the engine a "good" thing, however dirty oil is better than no oil :rofl:

YEP!

If you don't mind messing with the premix that's the option that makes the most sense however there is also some merit that should be given to the off gas decel thing so keeping your oil clean and your pump pumping along with premix is likely the healthiest overall option.

There are plenty of times when I need gas but forget to bring along premix when driving my DD cars so I can see how removing the OMP could potentially be a regrettable decision.

OMP Adapters - Rotary Aviation<br />.com

/end thread

LOL

I have two of these for sale if anyone is interested :icon_tup:

PS BEST option
PSS I don't use them because I don't like BS in my engine bay. Extra tank lines etc..... but some people LOVE these sort of cool reliability tricks

pretty bloody simple.. in 1971 mazda fed the OMP into the carb bowl

essentially premixing

they soon changed that

evolved to carb throats ( SD 12a )
evolved to housing direct and inlet runner ( 13b RESI / GSLE and s4/ s5 FC
evolved then to only housing direct ( FD )
evolved to housing direct , with rubber inserts and lower flow ( later FD )
evolved to housing direct,, but at the edges ( rx8 s1 ) , got lots of warrantee issues
evolved that to housing direct edges and middle ( later rx8 )

i hope you are seeing the pattern in this

the middle direct housing spot is where the motor needs the lube

premixing just blankets the entire rotor .. in all the spots it doesnt need it
and only a very small part of it is going to land in the hot spot in middle of the apex seal where you want it most

so what does all this extra premix and wasted oil do?

it turns to carbon and acetelene compounds when not completely combusted

what is already in your combustion chamber ? carbon and grit

so this pre mix oil magically stays wipe arse clean when it goes into the motor?


i pull plenty of engines down .. guess where the clean strip is on engines that run the OMP
-right down the middle of the rotor -

guess this OMP isnt so bad for carbon build up
.. and it is the oil distributed elsewhere,, and residual petrol from running too rich far too long that makes engines carbonised

so.. this premix.. tell me about its magical qualities again? how it makes the motor somehow cleaner,, but when i pull them down,, they are often worse?

how many premix motors made 250 000 km ?? ...not many... i bet

ask yourself why mazda moved away from bowl mixing into the fuel
.. i can think of a few good reasons that are still valid in todays cars , and one of them is octane
the other is continued lube when the motor is in decel

every time it revs up.. it has to rev down .. am i missing something or are you ?



if you have 300 rwhp,, then you need to keep the OMP ( more than ever before ) and add suplement premix as at those flows you may be dropping below the optimum ratio as determined by mazda in the SAE papers

PS
some of you need to change your oil more often
.. cant imagine the engine running very long on the carbonised and gritty engine oil that you seem to wish to avoid injecting for OMP

PS.. i run LPG.. with OMP .. my engines and rotors and turbos are SPOTLESS, and have posted many pics to prove it

OMP is not contributing greatly to the carbon build up .. but the lack of petrol is certainly helping keep it very clean

I am with Bumpstart have omp on all my engines and race cars and they have served me well . I do add a little bit of premix on the race cars

I dont know .

here is my view on the subject .

it can be annoying pouring oil every time you gas up , which is alot in the RX7 if you drive it often .

( Honestly after doing it for 3 years ) since I did it even before I removed my premix I dont really mind it its second nature gas stops take a little longer then normal But well I think it would be worth it .


When I took a look at my old housings you could clearly see a streak of shiny where the oil injectors were. That was an obvious sign that the OMP was not lubricating evenly .

Another thing is they do go bad . Mine was leaking oil from a bad gasket .

I jsut eliminated it thinking one less thing that will fail . and one more thing to improve the longevity of the engine / housings ,

BUT !

the OTHER downside to premixing . that i've noticed is that when you are OFF throttle you have no fuel going into the engine . * so if you engine brake alot could this not be a bad thing since it will not be receiving oil from your gasoline .

SOME ECU's have the option to add fuel to the car even off throttle which would theoretically fix the whole issue . But You would need to tune for it off throttle .

WHen I tried ,I could not lean out the injectors enough ( and it fouled my plugs pretty bad )

so I turned it back off .

When Its time to rebuild the motor again I will see if it was more of a help then a hurt .

Thxs for the feedback guys and very informative post bumpstart, thxs for provising all that info

I plan on driving my fd atleast 10k miles a yr and thinking premixing may get old and that's why I wanted to get your feedback.

Could be a dumb question, but how many people premix with E85? And how much premix do you need when you fill your car from empty?

I'm one of "those guys".

Just OMP:
*It's load and rpm dependent BUT it's crank-case oil. Carbon and deposits.

Just Pre-mix:
*It's clean oil that's designed to burn BUT when injector-duty goes to zero, so does hard seal lubrication. That can be a long (IMO significant) time coming down a hill and/or from high rpm and speed.
*You can't forget to keep pre-mix in the car.
*Some carbon.

OMP with adaptor and tank:
*All the good characteristics of the above options BUT packaging can be a huge PITA for a somewhat stock street-driven car.
*Wherever you end up installing the tank, you can't forget to re-fill it.
*Some carbon.

Personally I'm prompt with oil changes and use stainless lines with a stock OMP and guesstimate pre-mix at about half-rate...or about .5 oz. @ gal. I also have a simple AI system and don't worry about carbon. Bonez cat seems to be tolerating it just fine. No one following me has reported any smoke except a wiff on hard WOT. But hell, that could be my original 120k turbos. :)

I bought a S8 Mikuni OMP, new OMP lines and injectors from Ray, the RA adapter. I will custom fabricate a nice Aluminum Tank to feed the RA adapter, and I will only use high grade outboard marine engine TC-W3 oil

I'm no expert by any means (I have yet to actually get my rotary), but I spend a good amount of time reading picking up rx7 info. That being said, I think Howard Coleman is very smart and he actually made a thread about this:

https://www.rx7club.com/3rd-generati...-motor-887275/

Crank case oil and the OMP to me is like re-drinking your piss because "its still water".

https://imageshack.com/i/05pic1212522j

https://imageshack.com/i/jtimag0664voj

https://imageshack.com/i/myimag0646dj


all from EOMP motors..with the EOMP injecting dirt crankcase oil
only one came from a petrol engine, others LPG

.. guess which one


and my EOMP rate is turned up !

pics of the rotors are buried a few hard drives back so i cant retrieve them so easily
but they are pretty clean and not at all like howards pic of a rotor
( and my example is closer to 31 000 miles )

all up it is pretty conclusive evidence that the carbon that builds up on rotors
( and turbos )
is NOT entirely sourced from the OMP
and the OMP is a small bit player in that equation

howard shows a stock rotor , 20 000 miles in,, carbon locked
claims it was the EOMP / dirty crankcase oil

well in 20 000 km it will have used maybe 20 L of engine oil
( over estimating at 1 L every 1000 km )

and it will have used at least 22L every 160 km ( or 100 miles )
( heavily underestimating the fuel use , probs closer to 28 in reality )
that is at least 4400 L of petrol

or.....in US terms 1162 US gal petrol per 5 gallons of engine oil

or .. in laymans terms about 233 parts petrol :1 part crank oil

tell me again which is the major cause of carbon build up ?
it aint the OMP ,, and it is your over rich petrol mixtures


and that is before we compare the injection of oil at a variable rate
.. compared to premix where it is 100 to 130 :1 ALL THE TIME

or the SAE papers showing the ideal OMP rate at WOT
,, and its influence on temps.. IN THE MIDDLE OF THE SEAL

so.. hope all you with warped aftermarket apex seals is paying closer attention

i have seen enough to know that laying blame at the OMP and the crank oil
.. is doing yourself and your engine a disservice

So the real solution to this premix/omp debate basically still stands at
1-grab an adapter
2-make/get and external tank and run lines to omp adapter
3-add premix into tank for the omp to inject clean oil for lubrication instead of carbon/dirty engine oil

Problem solved...unless I'm missing something

If anyone of you guys with some old housings laying around Would post them up . i would love to have a comparison of the housings from a car that ONLY used premix , and a car that only used the OMP . Like I said above there was an obvious streak down the path of the Oil injector from my old motor if I can I will try and take a picture and upload it .

Maybe I'm getting old, but there's something to be said for having a "normal" car that doesn't need you to put 2 cycle oil in it. Just sayin.

Usually non-engines blow up from something silly like an overboost or fuel pressure drop/lean out, not from gradual wear in the housings.

^Agreed. But they aren't making new housings anymore. Prices seem to be going north pretty quick. And last I checked, no one has been successful in commercial re-chroming yet.
At least that was in my mind when I started supplementing the OMP. I'd bought new housings and was just hoping to reduce wear long term. Well see.

Yeah, these cars are old, and part availability is getting tight. It's not like a piston engine where any machine shop can mill the block, maybe do some cross hatching, and install oversized pistons.

+1 to everything bumpstart posted