Talic

I have a question about the 3 vacuum lines running infront of the thottle body.

1st is an engine breather so no check valve, engine needs to breath all the time.
2nd is from the oil squirters manifold this will see boost, so you need to check valve it so the boost doesn`t escape to the inlet.
3rd is from the jet air mixing, this will also see boost, so check valve it.

now this implies it being run to the intake on the turbo so...
the issue I see now that I'm doing the remote turbo would I have to run these 3 lines to the rear or can I have them on the charge pipe in the oem spot? without the checkvalves?

NgoRX8

iTrader: (1)

you can keep them on the charge pipe before the throttle body. check valve would not be necessary there since boost will be pushing one way. i'd recommend not hooking up the oil breather to the pipe though or you may get oil blowby.

Talic

i was thinking of just putting a catch can or a small filter.

Brettus

iTrader: (2)

*Lots of people run the jet air from charge pipe before the throttle - no check valve needed if you do that as Ngo says .
*Just put a catch can on the oil filler neck hose
*OMP oil line vacuum is generally taken from pre turbo intake pipe . I don't think it would be wise to allow that line to see boost . However I'm not sure that it needs to see any vacuum to function either . You may get away with filtered air from the same catch can you use for the breather - someone else may know ?

Talic

well i am using the omp so i would assume the vacuum port for it wouldnt be functioning? but the line itself would see boost when the throttle is open then vacuum when its closed? so putting it to the charge pipe should be acceptible?

Brettus

iTrader: (2)

/\ I don't think that is a good idea - but not sure

arghx7

On the series I Rx-8, as long as the OMP injectors are fed air before the throttle plate they are fine.



That diagram is from a non turbo FC, but Mazda didn't really change the OMP injectors until the 09 Rx-8's. The most important thing is that air is flowing in to the OMP injectors (either atmospheric pressure or boost), not out (vacuum from after the throttle plates).

The turbo FC's were fed from a nipple on the back of the intake plenum that actually ran before the throttle plates.

rotarenvy

the last part under the blue box is interesting. under boost your oil injectors aren't working. so if you have the OMP line connected pre-compressor then there is no oil injected after you start to run in boost. if you have the omp line after the compressor it will inject oil when in boost but it might be excessive due to the additional air flow.

what did mazda do on the FD and turbo cars?

maxxdamigz

iTrader: (1)

There is a post from MM maybe last year that talks about the ball/spring check valve in the OMP nozzle system failing. It was noted that in an N/A car, the atmospheric pressure on the back side is never less than the pressure of intake runner (WOT, they are ~equal) but if you did generate a positive differential like with intake port time extending past "BDC", the check value would prevent back flow. On a turbo application, you can plumb the LIM port into the back of the injector. That way, the pressure differential is always 0. However, under low throttle, you don't have atmospheric pushing the oil in.

Some of the above may be a bad idea, and I haven't thought about it too much. You can find that MM thread though easily and get some decent thoughts about the check valve situation.

Talic

in accordance to that diagram and text. that means in boost inside the chamber it will now push back the oil.
so wouldnt it be better to connect it on the charge pipe before the throttle body?
then when in boost it would be at 0 pressure due to both sides of the oil injector being the same pressure?
and hopefully the pump can still squirt in the oil?


would this be the issue with the forced inducted renesis killing itself if you dont premix?
i did 50,000 hard kms with my previous procharged running 8-10 psi without any issues only a 1 way valve run to the intake on the procharger.
but come to think of it then putting the check valve would be a bad thing to do since inside the chamber the boost will try to stop the oil from coming in?
unless the pump is strong enough to force it though the boost (as the boost wouldnt be flowing just pressureized)

Talic

this is all i could find after changing the search to omp check valve
https://www.rx8club.com/showthread.p...mp+check+valve
https://www.rx8club.com/showthread.p...mp+check+valve
first one is from turborx8 the 2nd is the one from MM

it looks like he suggests to bring it to the LIM to do a better job of the equal boost/vacuume
and if any oil does get pushed back out of the injector it will be running back in though the intake

correct me if im wrong but perhaps this is the best?

maxxdamigz

iTrader: (1)

I also wonder, though, if you run any vacuum lines around the TB, wouldn't that destroy your idle?

Brettus

iTrader: (2)

Well - I just read the whole thread and came to the conclusion that pre throttle plate is best .
I don't like the idea of connecting to the lim as that equalises the pressure in all situations - so no air flow . The object of the exercise as I understand it , is to have air flowing to help with atomisation.

But if you connect to pre throttle body you have boost in those lines and you will need to fit hose clamps to them all .
Liking the idea of leaving it hooked up to the pre turbo side and just premixing more and more

rotarenvy

it wont as the ones we are dealing with are the ones mazda designed. So it is factored in or doesn't make a difference. if you add a new leak around the TB then yes it can change your idle.

arghx7

I think you are misunderstanding what they mean by "vacuum." "Vacuum" and "pressure" are all relative.



As the engine goes through the four strokes, a localized vacuum pulls the oil injector check valve open. That localized vacuum is relative to the combustion chamber--it pulls air toward the intake port.

There is another source of vacuum in the engine, the source that we are all mostly familiar with. This is vacuum created by the restriction of the throttle plate.



This vacuum pulls air towards the throttle plate. You have to imagine the hoses for a second. As confusing as it sounds, the vacuum from the throttle plate will pull the check valve inside the OMP injector closed, while the localized vacuum of the engine will pull the check valve open. Think about vacuum as a pressure difference between two points, not as this thing that every engine produces. The illustration above from the Mazda carb rebuild manual explains it.

On a carbureted car, an extra restriction is placed in the intake and that's called a venturi or boost venturi. The extra restriction creates more of a pressure difference. The pressure difference creates more vacuum, and the vacuum is used to suck fuel out of the float bowl even if the throttle plate is fully open. Fuel injected cars don't have venturis because as I said they are restrictions and hurt performance. But the throttle plate still provides a vacuum to drive various things (SSV for example) and that can be stored in a vacuum chamber.