I was just wondering about this for when I get my ltx what would be beneficial or not beneficial about putting the larger injectors in the primary spot BUT still fire them as secondaries?

In other words it would be 680's or 720's in the secondary spot fired as primaries and 1600's in the primary spot fired as secondaries.

Santiago

 

Why do you want to run It this way? Have you taken the time to study how Microtech operates the FI's? It stages them. https://www.rx7club.com//showthread....hreadid=182032

 

I haven't been able to down load the manual yet. It times out every time I try. >_<

And all that is new and not understandable info to me as I haven't ever used an aftermarket EMS.

And I did say I was just wondering about it. I wanted to hear some info on what that would do. Trying to learn here man.


Santiago

PS I have read that thread about 3 times and I still don't get what exactly the gent is talking about.

 

I do it in reverse.

I run larger secondaries.

 

Yeah I understand that this is the normal way to do things. I just wanted to know what would happen good or bad if you swapped locations but kept the firing order that is stock. But apparantly Tony says the the LTX runs the injectors in a different way?

 

Interesting idea... haven't heard of anyone else doing this....

I can say this for you to ponder:

Obviously the fuel needs to be fully atomized for ideal combustion. THe further up the intact track (away from the engine) the more time the air fuel mixture will have time to become atomized. This is the reason that it is recomended to run a water injection nozzle as far from the TB as possible.

I *assume* (no fact, but it reasons to me) that smaller injectors will do a better job of atomizing fuel since they aren't dumping a large volume. Kinda like with a spray bottle, if you want extra fine mist you barely get out any water and as the volume of water increases the dropplets become larger. For this reason you would want the smaller injectors closer to the engine since they have less time to fully atomize.

A co-worker recently told me about a test study that showed places fuel injectors far up the intake track actually made more power. I'll have research that for myself I guess.

 

Wow, interesting concept. I would think the physical placement of the injectors primaries and secondaries has been carefully selected by mazda and I don't know if I'd chance it switching them.

Course you'll still want the primaries to be smaller but I see what your talking about in basically switching locations. You're definately thinking outside the box. Be interesting to know how a location change effects performance.

 

If you did that your engine would run pig rich at low RPM's. and just the same at high RPM's. So you would achieve no gain from doing that.


UNLESS you have a, lets say like 4-71 blower, and it gives more air/fuel at low RPM's then high, so you would need more fuel in the lower RPM's then you would in high. Because the 4-71/6-71/8-71... Run out of steam if you will at high RPM's. But since you don't have a forced induction system like that, you would get nothin buy losses from putting bigger injectors in the primaries.

 

You missed the point of what he is saying. He isn't saying to fire the 1600's as primary injectors. He is talking about moving the primary injectors to the upper mounts and the secondary injectors to the lower mount positons. This would not effect actuall fuel amount being injected... only the placement of the injection point.

 

With a stock ECU it would be very dumb, as the injector firing time (when in the cycle it fires not the duration) is fixed. If you're running an aftermarket ECU this is adjustable, so there'd be no advantage or point to doing this.

Where do you get these ideas...?

 

Generally...

Inboard injectors = better low/mid-range throttle response.
Outboard injectors = better atomization & homogenization = more power and less chance for detonation

Therefore, get back inside the box, and leave the injector placement alone.

 

This is cool info to know. Thanks! I might experiment if I am able to get another UIM.

But with what you said it would suck with the large 1600's in the primary spot(READ FIRED AS THE secondaries) since it wouldn't give it enough time to atomize. But the 680's in the secondary spot(fired as primaries) would probably work a little better right? more time to attomize the fuel in the intake.

 

Ok how about this one:

680's in all four slots but ONE additional 1600 on the UIM. The LTX12 can drive 6 injectors so I am fine.

 

So do you take 1 second to think about these ideas, or do you take a whole 3 seconds?

 

Where would the world be without people that think up new ideas? You don't have to be sour about me asking things. Afterall I am here to learn. If you don't want to help out with different ideas its ok other people are bound to see the thread and post info in a nice way. And no I didn't take 1 or 3 seconds to think this up. I was simply wondering what happens when you change injector location. Thats all. Now you don't have to be mean about it. With the information that was posted above it would be obvious to me and others that larger injectors in the primary slot would not have good atomization and would likely make the car run crappy. But I was thinking about the 4 680's and one 1600 up on the UIM because 680's are still close to the stock 550's' size and would probably make it have better response in the low and mid rpms as you mentioned but the 1600cc unit placed hire up in the intake further away from the cumbustion chamber would be dumping a large amount of fuel but its fuel spray would have more time to attomize. I thought that would be a better idea.

Santiago

 

Sometimes people forget what its like to be young.
And they also forget what its like to learn.
After this voluntary lapse in memory, I suppose, they become so damn bored they don't understand anything else except stringent "CORRECTION".

 

Like I said "for when I get my ltx" ltx means LTX12

 

i see that you are trying to build power, which is good by all means. your ideas are interesting and everyone that responded seems to have their own opinion. i think that it may work to a certian degree and with the right configuration injector, size, timing, pulsing. ect. it might work and make power. direct port injection seems to make lots of power.i'll say 90% of engines now have direct port injection. But the only real way of knowing if it will work on rotary engines is if some try it. good luck

 

I've seen some racers even have the fuel injectors and rails at the opening of the velocity stacks

Also... honda uses this theory in ther bike engines 2ndary injectors waaaayy up in the intake manifold.

 

Probably the same place Felix Wankel got his ideas from.

 

If your ECU can do injector phasing, I wouldn't worry about it.
The primary spots are the most "ideal" placement of the fuel injectors.
Mazda did the R&D, and it was printed in an SAE paper about this very subject.
The primary fuel injector spots produced the best fuel delivery numbers in terms of performance and efficiency.


-Ted

 

I was thinking about switching the front and rear rotor. What do you guys think?

 

88 RX-7 20B/T66 Money Pit Project


Maybe it'll go something like this.

 

do you have a link to these papers or any other SAE publications on the rotary. im interested.

 

"I was thinking about switching the front and rear rotor. What do you guys think?"

Tell us how it goes Evil.

Just about everyone here said that an injector placed further away from the intake port will help to ataomize the fuel. I have no knowledge or facts on this subject, but when i think about it, it makes no sense to me. the injector already sprays the fuel as a fine mist. it seems to me that the tiny fuel droplets in the mist would join together to form larger droplets, the longer u keep them in the air. i think this is how rain is formed. first it falls as tiny droplets, then on the way down, the tiny droplets join to form larger drops of water. if the same theory applies to fuel in the intake manifold (duz it?), then it would seem logical to inject fuel as close to the combustion chamber as possible. this might explain what slaker7 said, "I've seen some racers even have the fuel injectors and rails at the opening of the velocity stacks",

"Also... honda uses this theory in ther bike engines 2ndary injectors waaaayy up in the intake manifold.".

so what do u guys think about my theory?