xb2002

I am in the process of the re-assembly of the omp setup and I have installed the pump and lines. I have gone with the non sequential setup and I have done away with all the vacum solenoids. My question is do I hook vacum lines to the nozzles that secure the omp tubes to the housings? I have looked through the pile of excess, and I cannot find any vacum lines that I may have pulled off of the nozzles. I can probably post some pics if it would help explain what I am trying to accomplish. Also should I run a premix with the first tank of fuel for the break in?

XSTransAm

the vaccuum lines off the oil injectors are supposed to be plumbed into the intake before the turbo so they see a constant vaccuum.

xb2002

I connected a line to one and used a vacum pump... it held vacum.. Then I blew. I was able to blow air into housing.. So I connected them directly to the intake manifold. I am assuming that when it is not boosting the OMP has enough pressure to pump oil in the housings and under boost the nozzles probably spray the oil in. I hope its right... but it seems like the only logical explination as to why the vacum/boost lines are needed.

RXJJang

iTrader: (52)

I just converted to a single turbo and after much laborious forum searching, I believe the general consensus over this debated topic is to vent (with a filter) the vacuum lines from the OMP to the atmosphere. Read this thread: https://www.rx7club.com/showthread.p...ht=vacuum+vent

The purple lines are the ones in question.

XSTransAm

the nozzles have 1 way check valves in them. You should not be able to blow through it both ways.

mjw

iTrader: (1)

XS is correct, they should be connected to a constant source of vacuum. Do not connect them to the intake manifold, the nozzles are not designed to be under pressure.

xb2002

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Well I read that tread and I cant figure it out!

This is what I know(tested):

1... I can blow through the nipple into the housing (with it installed)

2... I can NOT suck any air from the nipple (check valve)

This is what I think:

3... vacum would do NOTHING when connected

4... boost would spray the oil into the housing with a siphoning effect??

5....There has to be some purpose of the nipples on the nozzles otherwise there would just be a banjo bolt there instead.

Can someone please post their comments/advice?

DamonB

Then they are working correctly. The vac nipples on the OMP injectors need to be plumber to a constant source of vacuum. The only place that satisfies that is in front of compressor wheel. I don't know why everyone argues about not adding the vac lines. Just because "my engine hasn't blown up yet" doesn't mean they aren't needed.

Here's a post from this thread:

The injectors are above the OMP and once the engine (and therefore OMP) is switched off the oil will siphon back down the OMP lines and into the pump. Then at the next engine start the OMP would have to prime the lines again before ever getting oil into the engine, thus starving it of OMP oil at startup.

That valve in the injector is like putting your finger over the tip of a straw. If you dip a straw into a glass of water the straw fills with water but runs out as soon as you lift it from the glass. If you put the straw into the water and then put your finger over the end you can then pull the straw out and hold the water in. That's exactly what the little valve on top of the OMP injector does; once vac is gone the diaphram closes across the top and holds the oil in the OMP lines so it can't drain back.

The OMP injectors would still function normally with the engine running without vac present on the valve, but the oil would siphon after shutdown. This means at startup the engine seals get no lubrication as the OMP has to prime the lines again.

rotarypower101

iTrader: (1)

https://www.rx7club.com/showthread.p...4&page=2&pp=15



Hey Damon, I don’t understand the statements that you are making that the OMP injector receives enough vacuum to open the diaphragm from the turbo inlet. From what I understand vacuum would hold the diaphragm closed and not open as you said.
I also don’t see if that were true, how would the diaphragm stop the OMP nozzle from siphoning back under that configuration unless you were to apply vacuum even when the car is off to avoid siphoning if it is an issue.

Here is wargasm’s video showing that the diaphragm is on the back side of the injector assembly, and would be held closed under vacuum from the top of the OMP injector to the turbo until suction from inside the engine exceeded the vacuum created by the turbo inlet.

http://www.zeroglabs.com/rx7/howoilmeteringworks.htm

xb2002

Thats what I'm thinking! I still feel that it needs boost to assist the spray at lets say 7000 rpm! Any more takers?

I feel that the check valve is there to prevent internal pressure from blowing out and to allow the oil to be injected (with assist under boost)

DamonB

The OMP nozzles never see boost. Their vacuum source is from the inlet before the turbochargers in the stock setup and they NEVER see boost, only vacuum when the engine is running.

I can't view the vid. Guess I need to download something...

RotorJoe

This is interesting. I can see both sides. But the vacuum diagram in the FSM shows that the nozzles are hooked up to the inlet side (always vacuum) of the turbos. I just redid mine. Apparently most people/builders feel that it should be hooked to boost pressure. Although this is wrong. Mine was hooked up like this for a while now and I suppose I was lucky I was using Proteck fuel lubricant.

Now another question: If you have had your OMP nozzles hooked up to boost pressure, could you have damaged the OMP system in any way?
Is there a way to test the OMP system?

Thanks

rotarypower101

iTrader: (1)

the copy I have says it is a divx, can you even download it, or is it just not playing on your windows media player?

I have read about the oil metering nozzles to no end I know, but it seems no one can really make sense of what it should really be doing in terms of the diaphragm. It is very conflicting as to what the purpose of the valve was really supposed to do if infact the OMP pump does release x amount of oil perhaps the vacuum of the engine does suck the oil that is in the banjo into the chamber distributing and helping vaporize the oil.
There is one thing that is undeniably true though, and that is that mazda engineers hooked it up to the front of the turbo inlet and it is either for the vacuum or simply clean air . Whether or not the vacuum is simply there to help hold the valve closed when the chambers are pressurized and open when the engine is under higher vacuum than the turbo intake I don’t know but that seems to make the most sense.
Though then the idea of applying boost to the injector doesn’t sound like such a terrible idea.

I personally just took 2 ratsnest solenoid air filters and glued them to the top nipples, because I was told it simply needs clean air.

Has anyone confirmed that the OMP lines drain back into the pump? That seems like a odd thing to happen or for mazda engineers to overlook? Any feedback or experience with this?

xb2002

I just tested the nozzle with a vacum pump and it holds 10hg then it drops to 0.

If they were hooked up to turbo inlet stock... then thats where they are going.

DamonB

Boost= manifold pressure. The chamber inside the engine where the OMP injector is located is not under vacuum when there is boost in the manifold. The oil is forced through the injector and into the engine by oil pressure and the OMP pump, it is not "sucked" into the engine.

mjw

iTrader: (1)

No your oil pressure takes care of that, watch your oil pressure gauge as you raise the revs..it rises, or at least it should. If you apply boost pressure to the nozzle you will be reducing the effectiveness of the oil pressure in my mind, say 50psi oil pressure that is fighting against 10psi of air pressure in the nozzle ..now you have a lubrication problem unless you premix.

RotorJoe

And I thought I was just trippin. But when I switched my OMP nozzles from the pressurized side to the inlet right infront of the turbo, my oil pressure had increased at RPM. Now it looks more "normal".

rotarypower101

iTrader: (1)

Just found this while brousing the page again, and thought of this thread.
Have you been able to view that video yet? It shows pretty clearly the way the OMP nozzle has to work (I know we have beat this issue to death but…)

“Negative pressure created in the rotor chamber would cause all the oil within the nozzle to be sucked out.”

http://www.rx7.net.nz/newrx7.htm

from this paragraph about 11 paragraphs up from the bottom “Apex seal lubrication has become a critical issue. In a race engine, oil supply to the rotor housing by means of injection was precisely monitored and controlled, whereas in the production unit, a larger amount is supplied, just to be on the safe side. Some of the lubricant is fed into the trochoid chamber through a metering nozzle. The previous nozzle's oil passage was 2.0 mm (0.08 in.) in diameter. Negative pressure created in the rotor chamber would cause all the oil within the nozzle to be sucked out.”

DamonB

I can't even make it download right now? It's hanging up it seems.

rotarypower101

iTrader: (1)

Damon, do you have the correct codec installed to play divx files?
Here is a link to a divx codec I installed on a computer here at school with just windows media that wouldn’t play divx files, until I installed the divx codec.

http://www.filemirrors.com/search.sr...vX412Codec.exe

You really need to see this video, I think it will change your view on how they work. I don’t think the OMP nozzles stop the oil from siphoning back down the line the way you describe, and the diaphragm is on the other side of the air line porting inside of the nozzle from how I think you describe it.

And it still seems like the oil is literally being sucked into the chamber, meaning that if boost is applied to the top nipple that it doesn’t restrict the oil flow, but maybe it could disperse it better(assuming the pump is not pressure sensitive, and releases the same amount of oil for each cycle regardless of the pressure in the line)

Not that I am running it this way, just stillwondering about it.

I think the purpose of the top of the OMP nozzle connecting to the intake elbow is, to keep just enough vacuum on the diaphragm to keep it closed and tight when oil is being pumped into the nozzle and avoid leakage through the top nipple(as it gets old or distorts looses some of its plasticity), while still retaining the ability to pull the oil charge into the chamber unabated.

rotarypower101

iTrader: (1)

And I agree with you it dosnt make alot of sense if you think about port timing and where the OMP nozzle is located, that the chamber would be under vacuum. But I have never seen anything stating what the pressure will be inside the chamber for a certain crank angle degree by degree. Maybe the internal volume increases fast enough to overcome the intake charge, though that would seem inefficient and odd.

zullo

My take on the video is that this is not an anti-siphoning mechanism. Rather it is simply a way to manage variations in combustion chamber pressure in the oil injector.

Here's my seat-of-the-pants analysis...

I assume oil is injected during intake. And (again) I assume during intake, the combustion chamber could be under positive or negative pressure, depending on boost etc... But the metered oil needs to be injected regardless.

So, the first scenario is negative combustion chamber pressure. The metered oil dose is delivered and greedily devoured, but there is still a draw on the injector. The injector's valve lets some air in so that the oil line is not sucked dry.

Second scenario is positive pressure. Oil can be pushed into the chamber anyway (because it is still at significantly higher pressure), and the injector flap seals so that the oil and valuable boost pressure cannot be blown out the top of the injector.

So... the vacuum lines run to a point before the turbos so that they always see *light* vacuum - enough to keep the valves sealed unless air is needed by the injectors, at which time the light vacuum is easily overcome and air is drawn in.

If you run the vacuum lines to the intake manifold, I would imagine you would see much lower pressure differential (none?) across the valve which would just leave it "flapping" and could result in it some oil leakage up the vacuum line.

Venting the nipple would likely result in an oil leak, as there is not a draw to seal the injector adequately.

jd to rescue

iTrader: (3)

Question: Is there a difference between the oil injectors on a 13B N/A and a 13B turbo?

zullo

I believe the NA has 4. Those injectors also have vacuum lines, which are plumbed to the intake manifold.

jd to rescue

iTrader: (3)

So internally (mechanically), do they operate any differently?