Simplified Sequential

[Whizbang]

hmm....that would be interesting, because that would required some decent chances in the the machines process...

[David Jerome]

Well, the sequential system works perfectly. Sadly this is the first time I have put one back with simplified sequential, wish I had done it years ago because it really wasnt bad at all. All the cars I put back sequentially in the past were very low mileage so I did all emissions etc. Pretty simple really, hopefully within the next 3-4 months I will get around to making a different hardline set to clear up the engine bay even more.

I think a custom setup that was paired with Charlie's coil relocation that moved the hardlines and solenoids over where the coil packs would sit from the factory would really clean things up and make replacing fuel injectors and omp lines much easier.

[afterburn27]

Glad to see you got the sequential system working David. The stock setup is really fun with a few mods. I certainly miss it and I have only driven my new setup for about 10 miles. lol

There seems to be a lot of confusion about the oil injector nipples and why they are plumbed into the primary intake elbow.

Simple answer... it was an easy place to source FILTERED air for the injectors. Under vacuum there is air being sucked into the engine through the injector nipples, and Mazda wanted to prevent dirt/dust/etc. from damaging the internals. The idea that they need vacuum to operate correctly is a MYTH. Hopefully I can explain...

First, the intake elbow is NOT a source of constant vacuum. It is atmospheric pressure. Anyone who has installed a vacuum gauge before the throttlebody on any car will know this. Under idle/light load the air in the intake elbow will be at atmospheric pressure. Under heavy load/boost there will be a VERY slight vacuum, negligible in comparison to vacuum that is seen after the throttlebody. I actually calculated the vacuum you would see under full boost and it was tiny. You would probably see slightly more vacuum if you were running a crappy air filter. But for most cases there is NO vacuum in the intake elbow. If Mazda wanted to provide a true constant source of vacuum they would have utilized a vacuum chamber.

If you take apart an oil injector you will see that it is nothing more than a banjo bolt with a check valve on top. There is nothing complicated about this check valve, it is simply there to prevent boost (and oil) from spraying back out under manifold pressure. Pics of a dissected check valve can be found here: (http://www.rx7club.com/forum/showpos...1&postcount=16). I have verified this with one of my old injectors as well.

When the engine is under vacuum it is “sucking” on the injectors. The check valve is open in this situation and allows filtered air to pass through the injector and enter the intake chamber. If the injector nipples were capped the engine would be placing excessive vacuum on the OMP lines and would quickly empty them. The OMP would not be in complete control of the amount of oil injected into the engine, the oil would be sucked out instead of letting the OMP “meter” the correct amount of oil.

DamonB has posted a great analogy of this process on the other forum:

An analogy of this would be you sucking soda through a straw. Imagine built into your straw was a pump that was supposed to control the amount of soda passing to your mouth as well as deciding how often to deliver a sip of soda to your mouth (this is what the OMP does. It decides when you get a sip and how big that sip is). If the pump were merely built inside the straw there are only two openings present; one in your mouth and the other in the drink. If you were to suck hard enough you could suck as much soda through the straw as you wished because you could suck it right through the pump, even if the pump were attempting to deliver a smaller amount of soda. If we inserted a tee into the straw between your mouth and the pump whenever you suck on the straw you'd merely suck air through the tee, allowing the pump to be in complete control of how much soda is delivered to your mouth no matter what you do at your end of the straw. We'd also install a one way valve in that tee so that when the pump is delivering soda to your mouth none of the soda goes out the tee, it all goes into your mouth.

When the engine is under boost the check valve is closed and the VERY small amount of vacuum applied to the injector nipples is not affecting the injector operation in any way, shape, or form. Again, the vacuum created in the intake elbow under boost is very small and would barely read on a typical vacuum gauge. When there is positive manifold pressure the OMP must overcome the boost inside the engine, which isn’t very difficult since the diameter of the injector nozzle is so small.

So, in summary the oil injectors should be provided with a source of filtered atmospheric air. It just so happens that a convenient location for this is the turbo intake. Personally, I use a pair of leftover solenoid filters. Do not cap the injector nipples, or plumb them in to a location that sees boost pressure. If you like to gamble you can just leave the injector nipples open, but be aware that there is a slim chance for some dust or other particles to enter your engine and cause damage.

Hopefully this helps a few people.

[Brent]

Really good information afterburn!!

[SPICcnmFD]

Originally Posted by David Jerome

Well, the sequential system works perfectly. Sadly this is the first time I have put one back with simplified sequential, wish I had done it years ago because it really wasnt bad at all. All the cars I put back sequentially in the past were very low mileage so I did all emissions etc. Pretty simple really, hopefully within the next 3-4 months I will get around to making a different hardline set to clear up the engine bay even more.

I think a custom setup that was paired with Charlie's coil relocation that moved the hardlines and solenoids over where the coil packs would sit from the factory would really clean things up and make replacing fuel injectors and omp lines much easier.

It really isn't that hard of a system to figure out once you get the emissions stuff out of the way.

[Herblenny]

Afterburner.. i have to disagree with you on the whole fresh air thing..

First of all, its a one way valve... If you tried to blow air in, air does not go in. So, having filter or clean air is pointless. If it was where air is being sucked into the nipple then I could say you make sense.. But as I made a point earlier that I've seen bad oil jets that blow both directions.. which means they are bad.

Second, there was a SAE article about the 99 oil jet vs older... Let me see if I could find that info:

Apex seal lubrication has become a critical issue. In a race engine, oil supply to the rotor housing by means of injection was precisely monitored and controlled, whereas in the production unit, a larger amount is supplied, just to be on the safe side. Some of the lubricant is fed into the trochoid chamber through a metering nozzle. The previous nozzle's oil passage was 2.0 mm (0.08 in.) in diameter. Negative pressure created in the rotor chamber would cause all the oil within the nozzle to be sucked out. When the engine accelerated rapidly, oil supply could not keep up with the speed. To prevent oil starvation, the previous system supplied a larger amount of oil to be on the safe side. In the new metering nozzle, the passage diameter has been reduced to 0.08 mm (0.003 in.), halving its volume of 0.0005 L (0.03 cu. in.). A new rubber seal is also inserted to fill a gap within the nozzle body where oil used to be sidetracked. Now, there is still some oil left within the nozzle after each suction, so that the lubrication system responds to the apex seal's requirement.

This article points out the importance of oil metering system for rotary engine... Again, Mazda would not go to an extent to change nozzle opening if they didn't think its important.. This article also talks about the oil left in the nozzle.. which the jet/nozzle is being served as a reservoir of oil. Again, the vacuum pull of the nozzle could help faciliate the oil being filled properly during higher load on the engine.

Again, the point I'm trying to make is even slight vacuum created by intake before the turbo will help facilitate the proper working of the oil metering system. And actually thinking about it, big negative pressure would be BAD for the nozzle.. Again, putting filter or no filter doesn't matter as its one way valve... Check it yourself.. And as always, I could be COMPLETELY wrong about this as I'm no engineer... but it makes sense to me

[afterburn27]

Originally Posted by Herblenny

Afterburner.. i have to disagree with you on the whole fresh air thing..

First of all, its a one way valve... If you tried to blow air in, air does not go in. So, having filter or clean air is pointless. If it was where air is being sucked into the nipple then I could say you make sense.. But as I made a point earlier that I've seen bad oil jets that blow both directions.. which means they are bad.

Hi Phil,

You are correct that the oil injectors contain a one way check valve, but you have the operation backwards. Air is allowed IN to the intake chamber, and under boost the valve closes preventing air & oil from blowing out. Check page D-17 of the FSM if you don't believe me. My brand new oil injector allows air into the engine. (I bought it to replace a bad one that was clogged in both directions)

-Matt

[Herblenny]

Matt, Let me check that when I get home... I thought it only sucked in but I guess I was wrong

[Herblenny]

Matt,

I just looked at the service manual online.. And you are right! It does blow into the engine side.. Opps!


But I still think its necessary to hook up the vac lines to the intake.. And here is the reason why..

I think the reason why mazda did this is to reduce the oil consumption when the engine does not need as much oil, ie idle. During idle, there is almost no vacuum created and air is being sucked thru the nipple of the jets.. As engine goes into load, the vacuum created by intake, blocks air going into the nipple and cause more oil to be injected into the engine. If you just put a filter there, air will still be sucked in vs. oil (but not sure what extend oil vs air will be injected into the engine). Well, that's the new theory I have.. I should have double check the flow of the jets instead of guessing

Also, you are right.. I also forgot that after intake ports on the iron is exposed, the oil meter jet opening is exposed at the same time. At that point, it will see pressure and hence 1 way valve must be one direction.. Sometimes I'm very stupid

[afterburn27]

Originally Posted by Herblenny

But I still think its necessary to hook up the vac lines to the intake.. And here is the reason why..

I think the reason why mazda did this is to reduce the oil consumption when the engine does not need as much oil, ie idle.

Yes, that is exactly why Mazda allows air to flow into the engine through the oil injectors. DamonB's "straw" analogy is great for explaining this.

Originally Posted by Herblenny

During idle, there is almost no vacuum created and air is being sucked thru the nipple of the jets..

Correct again.

Originally Posted by Herblenny

As engine goes into load, the vacuum created by intake, blocks air going into the nipple and cause more oil to be injected into the engine. If you just put a filter there, air will still be sucked in vs. oil (but not sure what extend oil vs air will be injected into the engine).

OK, here is where your logic gets a bit fuzzy...

The slight vacuum in the intake is not blocking air from entering the engine... the check valve is. There is pressure built up in the intake chamber (boost) under load, so the check valve will be closed. Even if you were applying moderate vacuum to the nipple it would have no effect on the oil injectors.

Again, remember that the vacuum created in the turbo intake is very very small (and only present under load). You could probably argue that the stock intake setup and a crappy filter might see a few inHg of vaccum, but that's it. Vacuum is only created after the throttle plates.

The oil injectors simply need filtered ambient/atmospheric air. The turbo intake is a fantastic location to source this, but individual filters will work just as well.

[Herblenny]

Maybe my wording is bit confusing..

What I meant was that the vacuum created by the turbo, pulling the air in (which you said is min. negative pressure) is enough to stop from getting the air into the combustion chamber. But also, the negative pressure being made by the combustion chamber could be small and short so small vacuum created by the intake could stop the air from entering.. If you look at the quote I posted, the volume of oil is 0.0005L or 0.5mL. Which is pretty small volume which tells me only need small amounts of vacuum created by the air speed thru the intake might be enough to stop air entering and causing bit more oil to be injected at higher load (high air speed thru the intake).

I also agree with you that once intake port opening in the engine the pressure of the combustion chamber will be positive and then the check valve will stop the air/fuel mixture to escape thru the oil injector port. But if it was still the case of clean air, mazda could of saved ton of money by just putting a filter on as you've stated.

I think the best way to figure this out would be to put a vacuum gauge on the oil jet nipple and see what kind of negative pressure it pulls. If it doesn't pull much, then my theory should hold true.. which is at high air speed thru the intake pipe causing higher negative pressure on the hose will stop air from getting in and increase oil flow... Otherwise, oil flow is just based solely on oil metering pump pressure and the air being sucked in thru the nipple. Which could possibly be true..

[afterburn27]

Originally Posted by Herblenny

Maybe my wording is bit confusing..

What I meant was that the vacuum created by the turbo, pulling the air in (which you said is min. negative pressure) is enough to stop from getting the air into the combustion chamber. But also, the negative pressure being made by the combustion chamber could be small and short so small vacuum created by the intake could stop the air from entering.. If you look at the quote I posted, the volume of oil is 0.0005L or 0.5mL. Which is pretty small volume which tells me only need small amounts of vacuum created by the air speed thru the intake might be enough to stop air entering and causing bit more oil to be injected at higher load (high air speed thru the intake).

I also agree with you that once intake port opening in the engine the pressure of the combustion chamber will be positive and then the check valve will stop the air/fuel mixture to escape thru the oil injector port. But if it was still the case of clean air, mazda could of saved ton of money by just putting a filter on as you've stated.

I think the best way to figure this out would be to put a vacuum gauge on the oil jet nipple and see what kind of negative pressure it pulls. If it doesn't pull much, then my theory should hold true.. which is at high air speed thru the intake pipe causing higher negative pressure on the hose will stop air from getting in and increase oil flow... Otherwise, oil flow is just based solely on oil metering pump pressure and the air being sucked in thru the nipple. Which could possibly be true..

I *think* I understand what you are trying to say, and I still disagree. Are you saying that even under load (boost) the injectors will be periodically sucking air into the engine?

Here's a question for you... how are the lines plumbed in the RX8? Or a N/A FC? They are routed to the intake (pre-throttle plates). There is NO vacuum present in the intake. In fact, here is an interesting diagram I stumbled upon that seems to prove my theory:

http://www.rx8club.com/attachment.ph...0&d=1179886044

[Herblenny]

Hmm.. Seems like you are right..

Here is the RX8 diagram..


Looks like its before the TB.

Air is led from the throttle chamber to the check valve. The reason for this is to prevent the suction of a large quantity of oil by the vacuum when the vacuum of the intake manifold and combustion chamber becomes high during rapid deceleration, etc. Consequently, the amount of engine oil measured by the metering oil pump is supplied, regardless of the vacuum caused by the check valve.

I guess I was wrong Looks like you were right.. just to suck in air and no other purpose. The picture you linked really help me see how it works.. and I also forgot it went in one direction and somehow I was thinking it still sucked in.. I'm stupid like that sometimes..

Thanks for the picture and helping me understand