Leaving the oil injectors open to atmosphere will work just fine. However, if you don't hook them up to a source of filtered air there is a very small chance that you will suck in particles to the engine when it is pulling vacuum. However, the risk of damaging the engine from this is very small.

Do not simply cap the injectors.

 

It,s amazing to me that people would take the chance on plugging the injector orfice? If you have ever looked at the ejector fitting in the housing you might change your mind on unfiltered air. I was unable to fit anything through this hole when mine was apart for rebuild. Infact the only thing I got throught it was some light! Need less to say it is an extreamly small hole.

Terry7

 

I think what people are doing is putting on a little solenoid filter... but you're right. That would be pretty dumb.

 

I remember every time some asks this there's a big debate... Some say they just need filtered air and some say they need to be tapped into the compressor inlet to provide "vaccume." I'm not touching this with a 10 foot pole.

 

This subject was already beaten to death over in the single turbo section:

https://www.rx7club.com/showthread.p...&highlight=oil

I know some 'expert' builders that hook them up to a boost source, which is absolutely retarded. Don't do it.

 

+1 Do not cap them off or hook them up to a source that see boost.

Another good thread on this subject:

https://www.rx7club.com/showthread.p...ghlight=vacuum

DamonB does a good job of explaining how the oil injectors work in this post: https://www.rx7club.com/showpost.php...2&postcount=95

 

Thinking about it, it makes sense. Emissions-wise, Mazda wasn't allowed to have any evaporative emissions, which can come from the crankcase. That's the reason for PCV valves and stuff. Putting the vacuum lines on the OMP injectors will allow them to breathe, but any potential vapors get drawn back into the intake to be re-burned.

I wonder if you could just use some of the little filters that are on the stock rat's nest - they'd probably push right on to the injector nipples. That would solve that problem.

I might have to hook my boost gauge up to those lines and see if they output any noticleable vacuum or pressure, like backflow from the compression of the engine or backflow of boost under load. That would answer that riddle.

Dale

 

There shouldn't be any vapors coming back out of the oil injectors because there is a simple one-way check valve inside them.


Those little filters should work perfectly.


If you hooked up a boost gauge you would probably see a very light vacuum when you hit the gas. The more restrictive your intake is, the more vacuum you will see.

Honestly, this is not much of a mystery once you cut one of these injectors open. There is only a very simple check valve inside. No pintle or other fancy mechanics as others on this forum have guessed. Applying vacuum to these injectors will not affect their operation in any way, shape or form. It just so happens that the stock primary intake elbow is a great place to source filtered air.