Simplified Sequential

[Whizbang]

Originally Posted by Herblenny

David,

I know I had also wondered about that before...

What I know is that oil metering jets are one way jets. I also know what when air is being pulled by the turbo, it will create vacuum by the intake nipple. I'm assuming the vacuum lines on the oil jets are facilitating oil injection at higher load (under boost). I've seen people run this line to LIM manifold nipple, but I think when you do that it does the opposite affect and could also distroy the oil injectors.

i would have to disagree with this partially, at least in terms of what is happening. When a volume (the intake manifold) is pressurized, the pressure WILL go in the direction of lower pressure. Which is the reason the air is moving in the first place (towards the engine). The air on the wall of the intake plenum increasingly approaches a "0" velocity.

Now, what is probably happening, is that there is pressure working against the oil jets. This is probably the reason that there is a line running to the oil jets (at least on all the FBs, and FCs i have seen). It probably is to help equalize the pressure.

If you read my thread on air and its working, you might remember this formula. M=DVA (mass flow = density x velocity x area)

Mass flow must remain constant in this situation. We shall assume that for a given density (due to pressure and heat after turbocharger), you have velocity and area as a variable. The air moving inside of the smaller lines and vacuum nipples will be moving faster to make up for the decrease area when compared to the intake manifold.

Meaning that any of that pressure in the manifold is compensated for and if anything, a pressure differential may form in favor of moving air/oil of the jet and into the intake plenum. This, coupled with the pressure of an assume good metering oil pump, will mean oil is exiting the nozzle.

Without good testing, this is the best i could reason.

[Herblenny]

Ok.. Well, again, i have to put a disclaimer as I'm no expert..

But you have to look at the reason of oil metering and why mazda would have gone extensive length to put a "jet" and vacuum lines to a intake source.

To start, we all know as rotor spins and after apex seal passes exhaust port, it start creating vaccum (expansion of combustion area) to suck in air/fuel. If you look at the position of where oil metering jets are, its just before the primary fuel injectors and intake (I think??). By this, oil is drawn easily into the chamber by vacuum created by the engine. We also know as higher the load and engine speed more oil is needed. This was one of the reasons of why Mazda has been spending money on R&D... and why Renesis had 4 oil jets instead of 2 on 13b-rew (someone told me new one has 6!). I believe that the reason for vacuum source on the jet is to provide and control oil level flow.. As more air is being sucked in thru the intake passage, it creates higher vacuum pressure, causing higher flow of oil to be injected into the engine. By not using the vacuum source for the jets, you might not gain the benefit of increase oil flow thru the jets.. I guess you could get away by premixing.. but why pre-mix and go thru more hassle when just simple vac lines could do similar job.

bottomline, I think certain things mazda did it to save money and certain things mazda did it so it will increase the life span of the engine.. In this case, we could clearily see the reason behind the jets, location of the jets, and why mazda put it. Otherwise, why would they increase the number of jets to 4 (6) on the new engine?? That's more money for them and labor they have to pay...