craigw1

as you guys might know, I am in the process of running in my rebuilt 13b. My question is around oil metering. I have ditched the electronic omp which came with this tii motor for obvious reasons. In its place I have put the omp from my old 12A. I then connected it up to the two oil injectors which go directly into the housings. The tips of these injectors I just blanked off. Now I haven't connected the OMP to the IDA which means that the OMP is only running at idle speed and so is pumping oil into the housings at its slowest pace. I am also premixing.

My question is :

1) should I even bother running the mechanical OMP at its slowest speed since I am premixing anyways
2) Should I just let the OMP run at slowest speed and not premix
3) should I 'fix' the OMP in a faster position with premix
4) should I 'fix' the OMP in a faster position and no premix

please make your choice

I am leaning towards (1)

81gsl12a

iTrader: (1)

just premix and no omp...thats what im doing but thats caz my carb didint have any hook ups for the omp and i didint feel like modding it

mr_ouija

Premix FTW, OMP FTL.

trochoid

iTrader: (6)

5, Leave the mop pump as it sets and pre-mix for now.

I premix and dislike it, but I can't go back to the mop system, took the internals out.

I prefer running the standard mop system. Since you are running an S5 motor with a 12A mop, run the mop and a 1/2 oz/gal of premix too.

craigw1

so thats it then

I continue to premix and omp stays pumping at idle speed

vipernicus42

iTrader: (4)

I'm sure you can come up with a good way to fix the OMP into "full on" mode so that you don't have to premix.... but I didn't know that the 12a OMP provides enough oil for the S5.

Is there a possibility of using an S4 mech OMP? Or one from an -SE?

One of those two in "full on" mode should provide more than enough oil

Jon

steve84GS TII

Mazda progressively reduced the amount of oil injected into the engine,even as HP numbers went up.First with the electronic controlled OMP,and then switching to single pipe OMP lines on the FD and Cosmo engines.These engines had oil injected only into the rotor housings,did away with the intake manifold oil injectors and still made 250-300 HP without oil related failures.
The 12A OMP idle feeding into the rotor housings should be more than adequate along with premix.
If you decide to stop premixing,then run the OMP off the throttle linkage and use good clean oil.You could always look up/search for the OMP output specs on the 3rd gen engine and compare that to the 12A engine.Both run just 2 OMP hoses and the FD being a later model,will likely use less oil,despite its higher output.If they match or are close,then you should have plenty of oil for your turbo 13B.

trochoid

iTrader: (6)

Taking data from the 85 and 87 FSMs, the mop output form the 12A to the S4 13B increases, nearly 5 times, if I am reading the tests correctly. Add another 25% output for the turbo. As far as the S5 and later electronic ones, they do put out less and the REW will run pre-mix ratios as low as 800:1 at idle.

craigw1

thanks guys, this is getting really interesting. I will try and fabricate some sort of linkage from the ida to the omp but it is not going to be easy as they don't line up as nicely as the nikki did with the omp.

my next question relates to the nozzles on top of those oil injectors. do they nee d vacuum ? Or can i blank them off (as I have done) ? or can they be left open ?

after searching the board the best example i could come up with was the analogy of the straw with a glass of water ie if you sip on the straw and then put your finger on it, the water will stay in the straw until u sip on it again. let your finger go and the water will run back down into the glass. This compares to the oil in the omp line....so hence i blanked it off (the finger on the straw) so when u switch off the engine the oil doesn't roll back down (water down the straw) and conversely when you power up, you have oil immediately coming thru rather than having to be pumped up again. am i making sense here?

aussiesmg

iTrader: (1)

I premix because the sump oil is not designed to be used as a 2 stroke oil is, I use Amsoil Synthetic and car burns cleaner and I find it no problem to add a little oil each fill.

I carry a small long necked funnel, add the premix, run a little gas down the funnel to clean it, dry the funnel as the tank fills and store the oil and funnel in a bag in the storage bin.

I find it to be easy and clean in this method.

Just my .02c