imloggedin

thats a good question. i was under the impression from the manual and talking to people that the vacuum is what pulled the oil in and atomized it. youre right though ted, it wouldnt work under boost and at WOT if thats the case. IF thats the case, it makes the system seem more inferior.

my guess is that their is pressure. it IS part of the oil system after all. thats probably what the throttle body to pump linkage controls.

the haynes manual specifies that the omp should discharge 4.5 to 5.5 cc at 2000 RPM in a 5 min period (on a TII). its gotta be pressurized.

HAILERS

The *AIR* line on top of the injector is to equalize the pressure on each side of the injector. If there was no *air* line on top of the injector the oil would be sucked into the rotor housing bigtime.

There is minimal pressure from the omp. You can put the source of oil for the omp(say a cup of oil), below the pan with a line b/t the cup of oil and the intake of the omp and the omp will suck it up out of the cup. The oil will OOOOOCH up the line at the same rate it goes up the lines to the injectors. Remove the line from the injectors and it'll ooooch up at the same rate. There IS NO real pressure going to the OMP. The oil that enters the cover is routed from the left side of the cover over to the right hand side where most all the pressure is dumped into the pan thru a split pin that holds the omp drive gear in place. Some oil goes up that OMP drive shaft to feed the omp. But have you ever seen the large *** hole that the excess is dumped back into the pan???? Ain't no damned pressure worth talking about from the engine oil pump to the OMP.

The OMP itself is a pump, and a very weak one at that.

The pressure is equalized on either side of the point the oil is delivered because if it was not, then the suciton of the intake stroke would suck the omp lines dry and cause excessive oil usage.

EDIT; rest of this post deleted for foul language and attitude. Jesus H Christ ...go take .xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xx

HAILERS

If anybody out there ever owned a non turbo first gen RX-7 (that excludes NZCON), you'll remember that the omp on them fed the oil ........into the float bowls on the carb. Sort of premix, eh????

Someone please close this goddamned OMP premix thread and bury it in the backyard and never resurrect the sucker ever. Just riles folk up and helps no one.

imloggedin

it does serve some purpose. id certainly like to know how exactly the omp works.

RotaMan99

I was thinking of N/A or no compression periods but you do bring up a good question when actually boosting. Why I didn't think of this before is beyond me. Time to crack open the oil pressure tester and see how much pressure the OMP can build.

You will see no pressure on a gauge on an n/a or no compression periods on a turbo. It does not rely on vacuum at pull the oil through. So WOT on an n/a is no trouble. The flow is to slow to build any real pressure. Now if there is compression in the intake, I wonder how much pressure the OMP can provide.

HAILERS

Ok. Anybody that is really interested in the oil metering pump and the injectors, go here: http://wombat.sevarg.net/RX7/RX-7_Training_Manuals/

Download the LUBRICATION section. It's a very small download. Go to page 4-5 and read it.

Especially the words "The oil nozzle has a one way check-valve that acts like an air bleed to prevent excessive suction of oil and to atomize the oil."

"When vacuum is created in the combustion chamber and intake manifold during the suction period, the checkvalve is pulled open and allows air to be mixed with the oil."

"During the compression period, pressure is applied and the valve is closes, to prevent backflow of the oil into the connecting hose."

Ice_Wolf

Ted's my hero, along with Aaron, dDub, and Ice Mark. Needless to say they have helped me with an insane ammount of things on my car.

NZConvertible

All this blah, blah about the check valve in the nozzles and it's clearly explained in the Training Manual. Some of you guys should read more...

Boost doesn't matter at all, because during the intake stroke there's always a greater pressure at the manifold end of the air line (before the throttles) that at the nozzle end, hence air flows from the TB and through the nozzle.

RETed

That doesn't make any sense.
The entire intake is pressurized equally.
If the turbo is making boost, then the engine is at WOT or close to it.
This means the TB is open or close to fully open.
There is no restriction from the TB.

There has to be pressure in the oil injection system.
How can you inject oil under boost?
It doesn't matter what the check valve does or if there is an equalization of pressure across the oil injector.
The oil (pressure) still has to push it's way into the engine...against the boost pressure.
If it cannot do this, then there is no oil injection under boost...which is a stupid assumption.
The oil injection is high pressure but very low volume.
The oil pressure coming off the front cover is very high - something like 150psi?
Remember, it's called an oil METERING pump, although the word "pump" is not used in the strictest sense in terms of producing pressure.

Yeah, blah blah blah, you guys like to regurgitate the references, but you lose sight of the fact of basic engineering theory.
You can only get liquid flowing from one area to another area via a pressure differential, period.
Since we can throw out the fact that the intake cycle has nothing to do with it - since at WOT, the engine is either at "0" or positive pressure from boost - the only other deduction is that the oil has to be pressurized through the oil injection system.

Oh, now I understand where the word "compression" came from.
It was just a bad translation from the original Japanese text.
Apologies for pointing fingers for bad use of the English language - you were just taking it verbatim from a bad translation! :P


-Ted

Spectator

iTrader: (1)

Ooohhhh stfu.

I know pretty much exactly how the system works. Dont assume you are the only one that knows anything.

No **** sherlock.

RotaMan99

You must have used premix in the wrong context then.
You either know exactly how it works or you don't. I doubt you know exactly how the OMP operates internally and how its built considering you said below

Yikes. A little high. Try less then 100 and most of the time AT the OMP, there would be much much much less since the oil bleeds off into a larger hole to enter into the pan once it reaches the OMP. The oil pump does not provide any pressure through the OMP system.

imloggedin

i already quoted the s4 training manual like 15 posts ago.

i agree with Ted

HAILERS

Juuuuust in case someone missed it...................the omp is a PUMP. How do I know this? Easy. I removed the omp and blocked off the supply of oil from the ENGINE OIL PASSAGE. Then I drilled a hole in the body of the omp and installed a metal pipe.

On the pipe I installed a piece of clear fuel tubing (small engine fuel tubing). I put the other end of the tubing in a bottle of two stroke oil UNDER THE CAR. Like below the oil pan.

Then I started the engine and held the omp rod full up at 2000 rpm. The oil ooooched up the clear fuel tubing and into the omp body then out and up the omp lines. Pretty good little pump.

And I covered my ***. I removed the outlet lines from the omp and watched the oil oooch up the lines. I'm trying to say the other end of the line was not connected to the injectors, so there's no possibility of them causing the oil to rise in the lines. Just FYI.

I'm giving serious thought to removing the air feed line off the back of the throttle body and putting a vacuum gauge on it and then go boosting down the hwy to see the vacuum during boost.

RotaMan99

I feel for you then.

RotaMan99

Thanks you HAILERS. I guess you and I are the only ones that know this. Considering the working idea I have that is pictured in this thread.

This would be interesting. Please do HAILERS. I have never had to deal with a turbo engine so that actual thought of the side effects of the boost pressure never came to mind.

imloggedin

is that pump strong enough to overcome boost? if it can then the boost would just close the check valve wich doesnt close the oil injector line, just the path to the air line. so it would still inject but it wouldnt be atomized.

somethings off.

imloggedin

also i dont understand how a mechanical device is pumping with nothing to power it. ive never seen a pump run without some sort of power.

RotaMan99

It is being powered by the engine off the same gear that drivers the CAS.

This is what im going to figure out. I started setting up the test last night. Internally, the OMP is so underdriven, internally it seems to pump to slow to provide any real pressure out the OMP lines.

Yes I know that for flow to happen, the pressure has to be greater on the actual flow of fluid then where its going. You will not see 2psi, 5psi or 10psi in the OMP lines while not boosting and especially while driving an n/a.

Im curious to see what the results are HAILERS.

HAILERS

The pressure is the same on each side of the hole in the rotor housing. Probably less on the engine side of the injector.



The spider hose has the same pressure being supplied to the intake ports on the housings. On the intake stroke I'm sure there is LESS pressure in the rotor housing on the intake stroke than in the spider lines due to what??? The area being uncovered in the rotor housing getting larger as the rotor goes thru the intake stroke.


In fact I'm sure there is vacuum being pulled by the rotor on it's Intake stroke. That hole in the rotor housing is not located in the area of the compression stroke.

The omp's pressure isn't anything to brag about. I'd wager, and win, that I could stop up that line with my little finger.

And by the way, when I put that bottle under the engine, I later did a output check on the outlet lines and I exceed the FSM requirements. This is an original omp from 1987. Ain't a wearing out.

I'd suggest going out to your car, pulling the spider feed line off and capping the nipple on the intake manifold. Then by hook or crook attach the spider feed line to a vacuum gauge OR your boost gauge. The go boost the car for a good period of time and I'd bet you see vacuum on the gauge DURING boost.

I might do that tomorrow...maybe.

On a turbo I'm betting there is low pressure during boost on the intake stroke despite being in boost. Lower pressure than exists on the top of the nozzle.

imloggedin

i was talking about when hailers did his test. i thought it was off the car.

HAILERS

Remove it and take it apart. It has two cylinders internal that are driven by the input gear which is a worm gear. The input gear is driven by the shaft mentioned in the post above.

imloggedin

yah i figured it was being driven on the car but i misread your post about your testing.

HAILERS

https://www.rx7club.com/forum/attach...0&d=1164547073

This should be a jpg of the guts of a OMP series four.

melicha8

iTrader: (1)

another picture for help, this was during my omp rebuild. It was very easy to rebuild just a couple orings. I don't know why one side has to be right and one side wrong. Why cant we say both methods of lubrication were good enough for the factory and leave it to personal preference.

PinkRacer

Our OMP failed on the race car when the previous owner had it. It blew up the engine.

Anyway, no more OMP and we run premix AND we use leaded gas because it's a racing application. One point of failure eliminated.