[/img]http://www.turborx7.com/images/Technical/vacuum_hose_diagram2.jpg[/img]

stock vacuum diagram. looks like the oil metering pump line pulls vacuum from the intake of the primary turbo.

fuel atomization comes from the turbo intercooler crossover pipe from factory. I just replicated this on my single turbo set up.

That's what I'm saying—the OMPs aren't vacuum or boost, they are just atmosphere, and possibly a vent (i DO know that if your nozzle fails, it pukes oil into your intake in the stock system).

I have an extra 1/4" nipple on my filler neck, which is otherwise vented with a -10 AN line to a large Jaz can with big filter on top (so atmosphere). That might be an easy place to plumb the OMP lines.

You're not going to pull any vacuum off the turbo inlet with that little vac line, what with a big opening for the filter—think about it. Why would air be sucked from that little tube, when it can pull from a 3-4" opening.

You're going to want "filtered" air.

I think there is a lot of confusion because people always refer to these as Vacuum hoses.

Really, depending on where the hose is plumbed and current engine operating conditions, there could be Vacuum, Atmospheric pressure, or Boost Pressure.

The filler neck is "filtered" at the catch can, but it might not draw "clean" air in the sense that it will be mixed with crankcase fumes... I found a neat little dual inlet breather filter with mounting tabs on Amazon, I can just route both lines to that, and mount it someplace visible so that if it pukes any oil as indication of a failed nozzle, I'll see it.

I wouldn't be concerned about crankcase fumes, only dirt getting to and clogging the nozzles.
On one hand drawing crankcase fumes out of breather would kinda be like the way the PCV was intended to work, on the other having evidence of a failed nozzle could save an engine.

If I hadn't sold my mini Jaz can/breather and bracket for the big one, I'd just hook that back up.

Sure it pulls vacuum from that little tube. Just the same way as my boost controller shows vacuum when the engine is running and shows vacuum in all those lower cells. Same as with the MAP sensor and anything else.


If anything, being connected to the intake and when boosting a lot, there will be a hell of a lot of vacuum. If you improperly size a small air filter on a turbo, you can see the air filter suck in its top. The intake pulls a lot of air, regardless of the size of the tube. I run my oil filler neck to catch can to intake just like the later model rx7's.

what I'm saying is, the "vacuum" is being pulled by the engine in the case of the OMP injectors, not vacuum being pulled by the turbo away from the injectors as a "vacuum" source like the vac tank would have. As I read their operation, the lines simply allow the engine to draw air through that system... it's not using the suction of the turbo to suck air away from the injectors.

So you could run the lines open and just inject a tiny bit of unfiltered air, or run it them to a filtered source,like a mini breather filter.

ok I gotcha.