spoolin93r1

i know with the stock twins the lines from the top of the oil injectors plumb back into the primary turbo inlet. i recently went single and couldn't figure out where these should go. do i tee these into a vacuum source or what?

DamonB

They need to be connected to the turbo inlet as that's the only place with vac 100% of the time when engine is running.

spoolin93r1

so in other words, i need to rig something up? lol

Snook

iTrader: (12)

basically from the mouth of the compressor side you need to have a piece of metal or other ducting with a nipple in it and then the filter infront. not just filter on the turbo. its the right way to do it though thats how it needs to be

spoolin93r1

well i didn't exactly want to drill a hole in my turbo for a nipple, so i was going to make one to attach to the filter housing, since it'd see the same amount of vacuum as the turbo inlet itself. turns out there was a hole that was tapped in the back of the filter with a plug in it. i took the plug out and found a 90* vacuum fitting in my 'extra parts' bag that just so happened to fit perfect.

cliff's notes: damn greddy and their non-english instructions! lol

CCarlisi

All they need is filtered air. I don't think hooking the lines up to a vacuum source under any conditions is ideal for two reasons: First, I traced the hard lines and found they draw from the filter on the turbo, not the UIM in the stock system (granted it was awhile ago). Second, I believe I have a working understanding of the system, as I will try to explain below, and I think drawing from a vacuum source will counter act the purpose of the air inlets at the top of the nozzles.

Here is a brief explanation of how they work. Imagine the nozzle as a simple banjo bolt with the oil metering lines pumping oil into the side of the bolt and out the bottom. Under zero boost/zero vac the amount of oil that comes out of the bottom of the bolt is determined by the amount oil volume the pump is pushing through the lines.

The problem is the oil is metered into the combustion chamber, which operates under vac and pressure. The system deals with these two conditions separately.

Operation under vacuum:
If a simple banjo bolt was used the motor would exert vacuum on the nozzle, basically sucking the oil right out of the lines. Oil flow would be regulated by the amount of vacuum the motor was producing rather than electronically.

To compensate for this add an air inlet to the top of our banjo bolt above the oil metering input. Now the motor has two sources to draw on in its attempt to equalize pressure. It will still draw oil from the oil metering lines, but it will also draw air in from the inlet on top of the bolt. The end result is the amount of oil metered in under vacuum should be REDUCED.

Boost:
Under boost the conditions in the rotor housing reverse; the air in the chamber is pressurized. Under boost the motor will try to force air OUT through any path it can find.

This is compensated for in two ways. First, the computer kicks up the output to the oil metering pump so that the oil pressure in the lines exceeds the rotor chamber pressure. However, the air inlet provides another out for the positive air pressure. Air will back flow up into the nozzle, and out the air inlet, taking with it a good portion of the oil that was supposed to be metered into the combustion chamber.

To prevent this from happening add a one way valve, that allows air in, but not out, to our banjo bolt with the air inlet ABOVE the point where the oil lines feed into the bolt. At this point we have now duplicated the stock oil metering nozzle.

[Air filter]
||
||
[Air inlet]
[1 way valve \/ ]
[Oil metering entry into bolt]=======oil metering pump
[Nozzle tip]
[Combustion chamber]

To recap, oil is metered in through the side of the bolt under the one way air valve that is open to the atmosphere. Under boost the one way valve seals to prevent backflow out the air valve. In the same way, oil pressure prevents backflow into the metering lines. Under vacuum the one way valve opens allowing the motor to suck air into the housing rather than more oil than is necessary.

If the air inlets are plugged into a vacuum source it will increase the oil supply under vac by preventing or making it more difficult for air to be drawn in through the air inlets.

Hope this helps,

-Chris

spoolin93r1

the inlet on the turbos are constantly under vacuum, that's why they are pumbed there. i just wasn't aware of why or how important it was. i guess if that's the way mazda designed it, that's how i'll continue to use it

DamonB

Did CCarlisi check to see if NA rotary engines have vac lines on the OMP injectors?

Oil flow is regulated by the OMP; period. The engine cannot get any oil that the OMP does not send it, hence your engine is toast when the OMP fails rather than the engine merely sucking up all the oil it wants through the oil injectors. The OMP "meters" (sends) small amounts of oil up the lines and it alone determines how much oil will be sent to the oil injectors, therefore it alone determines how much oil will be injected into the chambers.

The reason the oil injectors are plumbed to the primary turbo inlet and not the UIM is because the inlet is the only place that sees vacuum 100% of the time. Anything downstream of the compressor sees both vacuum and boost.

greggtr

Yes, NA rotaries have the same setup. However, if I'm correct the one way valve is not necessary on an NA car.


Do you also believe that the amount of fuel injected into a motor is determined strictly by the amount of fuel line pressure? If so then why do fuel pressure regulators reduce fuel pressure by about 7psi under vacuum? Why would an oil line be immune to the effects of a vacuum draw?

Best,

-Chris

greggtr

Just so everyone knows my account seems to have possessed Greggtr's so please direct all negative responses to me not him

DamonB

No, but if the fuel injector were to never open you could run thousands of pounds of pressure and yet never get any fuel into the motor. At the same time you could put all the vacuum on the fuel injector you wanted and never get any fuel either. You're comparing fuel systems to OMP pumps and that is not a valid comparison. The OMP acts as both the pump and the "gate" to the oil supply. The OMP constantly opens and shuts that gate. It regulates oil volume not by line pressure but by how much oil it allows into the tubes.

The OMP is a stepper type motor; it is not a continuous duty motor like a fuel pump is. It not only supplies the pressure ("force") to drive the oil into the engine, it also measures that oil into small amounts; deciding how much to send based on its maps from the ecu. If you watch the OMP lines at idle you can actually see the oil arrive to the injectors in small "spurts" as the OMP meters it out. The OMP acts not only as a pump but also a gate between the oil supply and the oil injectors; if that gate is shut there is no oil allowed up the tubes.

Because a fuel pressure regulator is built for an entirely different job. Don't compare the fuel system to the OMP system.


The oil is immune to the effects of vacuum draw as you call it because the injectors can't get oil that isn't there; the OMP meters out the oil to the injectors. Therefore a fresh engine with high vacuum at idle won't draw any more oil up the tubes than a worn motor will; the OMP always decides how much oil is available to the tubes and when to send it. The injectors cannot draw any oil if the OMP won't let them have any, no matter how much vac the engine puts into the lines. The vac line attached to the oil injector has a diaphram between it and the oil supply; that vac line does not have access to the oil supplied via the tubes.


Because the air valve is in fact always open when there is vac on it. 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.

DamonB

Log out, clear cookies and log in. That normally fixes it.

Snook

iTrader: (12)

I dont have complicated arguments like you guys but I say do it exactly like mazda did and thats on an inlet tube before the turbo. If you are still worried about it not working then premix on top of that end of story. Also, I believe it will help to get the gotham ss braided omp lines because they seem to be a little thicker, wont crack, and make the most direct shot from omp to the injectors with minimal bends unlike the stock ones.
-Yanni

BigIslandSevens

iTrader: (4)

Great explanation DamonB!! I was thinking of how to explain it in the easiest to understand way.

The straw comparison is soo bitchin. You couldmn't be more spot-on!. Somehow this should be tagged and noted for this explanation on the operation of the injector valves. Clears up MANY mis -conceptions.

Garrett

I've had mine vented to the atmosphere and it works fine and has for over a year. My friend jayseven also has the same setup as me and does the same thing. There is absolutely no problem with venting them to the air.

Garrett

BigIslandSevens

iTrader: (4)

As far as the operation of the oil getting into the engine you are right. BUT, As DamonB pointed out if you were to watch you OMP lines after shutdown, The oil would eventually Siphon back down to the OMP. ( Not as soon as the engine is off but within 5-10 minutes probably.)

The only down side is that for a few brief seconds the apex seals will not be getting the oild needed at start up. Once the OMP lines are primed, the injection function is back to normal.

On a side note, When i had my car built by XS about 4 years ago they hooked the injectors to IC piping providing it with boost not vaccum. FWIW: When my engine went, there was a nice chunk of apex seal missing from the dead center of the seal. (Where the oil "should" be squirting) Maybe an effect of not haveing primed lines at the start, IDK.

spoolin93r1

well mine were vented to atmosphere and occasionally there'd be oil leaking from the line. that's why i was wondering

DamonB

If oil was coming out the nipple where the vac line is supposed to go then the diaphram inside the oil injector has ruptured. As I explained earlier the OMP system will still function normally in this case but the injectors will be temporarily starved of oil at startup until the OMP primes the lines. Replace the oil injectors.

Garrett

Boost not Vacuum? If you have it hooked into the IC piping then when you aren't on boost you have vacuum from the turbo to the engine. Am I not thinking straight on this?

BigIslandSevens

iTrader: (4)

I don't think you are. When you shut the TB Vaccum is created WITHIN the engine. Not in the IC piping.

That is why we have BOV so that when vaccum is created inside the engine by the TB closing The BOV opens and relieves the pressurized air Still flowing from the turbos to the TB so the piping doesn't blow off.( no pun intended)

Vaccum would be present on the AIR filter side of the compressor housing.(Because air is being"sucked" into the turbo and not "blown" towards the engine.) Not after unless past the TB. Make sense.

teeter

SOB...I hate it when these things bite me in the ***...

when I was putting in my single turbo I mis-read the vaccum diagram AND asked someone's advice and the answer both times was to hook up that line directly to the UIM.

So...I just went and put a check valve in line till I can work up a port on the back side of my air filter...

BUT...I can't suck air out of the injectors...but if I blow into the line...air will go somewhere. Where is that air going? Have I ruptured something?

wonder if this explains my smoke at start up...

thanks
john

turbojeff

iTrader: (30)

Someone else might have stated this...

There is practically no vacuum in front of the turbo. Most all of the vacuum happens after the throttle plates.

spoolin93r1

so if i have oil seeping out of the ports on top of the injectors, that means i should replace them pretty soon then huh?

DamonB

Yes. Any oil leaking out from there is OMP oil that didn't make it into the engine. Not a good circumstance...

Premix in the meantime to be safe.

DamonB

Just for the hell of it I attached my boost gauge to the primary intake elbow. The guage isn't capable of measuring the small vac reading There's certainly plenty of vac available as I noticed when I cupped my hand in front of the primary intake a couple weeks ago (airbox was out), but the amount is not near as great as what's behind the throttle plates since they choke off the intake tract.

There's still plenty of suction present to be useful though. You guys go suck on the ends of your boost gauges and tell me what kind of reading you can get You may be able to make the needle move but it won't be much. More than enough to open the little diaphram in the OMP nozzles though.