How to choose new injectors for Mazda RX7

I have an '87 normally aspirated RX 7 that I am about to install a new tuneable ECU. I discovered recently that when I had the present injectors cleaned and tested about 10 years ago that one of the injectors just barely passed,  (flows too much) and I would like to get some new ones. I can't seem to find anything in my service manuals that specifies what the rating should be. I did find on someone's website that apparently the NA version had 460cc (red) and the turbo version got 550cc (tan). I also know that there were two types of injectors and mine are "low square center" while the other style supposedly fits they will need some wiring mods which I do not want to do. I will be scheduling a trip to the dyno in the very near future.  The dyno shop feels confident they have a spare set of injectors but they are over an hour away and it seems very risky to arrive there and hope they are the ones I need.

So my thinking is that there are only so many different injectors available and the various manufacturers all use a very similar injector. If I can determine what cc rating I need, how do I figure out what other vehicles use an injector that will work on my car. 

I have been experiencing a major problem lately finding any competent businesses when buying parts or services for both my race car and our DD. Everywhere I go the pros know way less than I know, which isn't much. So anyone have a source that is knowledgeable? I don't mind paying a little extra if I will get the correct answer and component the first time, I'm tired of dealing with knuckleheads. The injectors are NLA from my typical rotary suppliers.

TLDR: I need new injectors for a rotary engine is there anyone out there that is worth talking to?

'87 could have low impedance or high impedance.  The late high impedance injectors (14 ohms give or take) have offset keyway connectors, while the early low impedance injectors (3 ohms-ish) have standard Bosch EV1 connectors.

460cc/minute is, IIRC, at 2.5 bar, not the 3 bar normally used.

Which ECU are you going to be using?  The easy button is two injectors in the 800-900cc range in the primary position, and no secondaries.

Getting an Adaptronic's I believe,  need to call the US distributor to confirm it will work with my engine. Seems like they are designed for turbos but the guy I am dealing with says they have a great product and support. 

My mechanical abilities are improving and I dig way deeper into things now but still am a bit clueless. How do I determine what I have in there now? When I pull one will it have any numbers or anything for reference?

I forgot to mention that this is a track only car, so no need to worry about meeting emission standards. 

Thanks for your expertise. 

Probably one of the most trustworthy places you’ll find:

http://rx7.com/store/rx7/fcfuel.html

In reply to amg_rx7 :

Thanks, some how I did not know about these guys. been supporting the other two big names for all these years. Will give them a call later today.

I have some injectors Chuck. Let me check what they are. I think they're S5 N/A injectors.

The first question should be "What has been done to the engine and what is the goal"

Good point, engine is mostly stock but a hybrid. It has an S5 bottom end with an S4 intake, a cold air intake, the rats nest has been removed, I run premix at 100 to 1 and when it was originally built the stock ECU had something done to it but I'm not sure what. Was a total newbie at the time and just told the guy to make it run and keep it reliable. Fast forward 10 years and the fuel system has been running super rich he entire time and destroying components,  mostly exhaust parts. So now the mission is to get a proper tune so I don't asphyxiate the people behind me anymore and if lucky have a slightly more powerful engine with much better response.  The goal for the engine remains the same; use good reliable components, have dependable power and last for a decent amount of time. 

I have had a hard time finding out what is supposed to be in there for injectors, what I really have and what  I need to make it run the most effectively.  I believe I found the answer today but will see what options other people suggest. 

I spoke to the US Adaptronic rep today and he had the following recommendations for  additional parts to go with the new ECU. Add a wideband O2 sensor, add exhaust gas temp sensors and a fuel pressure sensor. For injectors he thought the yellow RX 8 Secondaries would be the way to go. About 460cc's, reasonably priced and readily available. Going to run that theory by my dyno guy and get his thoughts and would love any input from the GRM hive.

I have been battling with local incompetence lately with the wife's DD and need some good quality information for a change. It amazes me how little some people know and yet keep their jobs. Time to rely on the real experts,  the ones that do things not just read about them in a picture book. 

I am into time trials and am an intermediate/advanced level driver but totally outgunned in my class with the club I usually run with, so I am not spending money just to chase a trophy but looking to enjoy the car as much as I can while having it run reliably.  It disturbs me a little to be spending as much on these parts that I am but if it works the way it should, this could be the last high dollar non crash purchase I should have to make for this car. I hope to be able to keep doing this for about 10 more years.

So bring on your opinions.

imgon said:

In reply to amg_rx7 :

Thanks, some how I did not know about these guys. been supporting the other two big names for all these years. Will give them a call later today.

Yeah, they are in TX and have been around a while. They are hands on and have been great resources when I needed to get a competent person on the phone to talk. 

IRP is in NJ as well if you need a rotary mechanic closer to you. Not sure if he’s done much NA FC setup and tuning though. The guy they use to tune their customers turbo rotaries is pretty good 

They make rx8 injectors in a few sizes.

They bolt right in and offer far better spray patterns.

That was my go to when I was running a rotary.  They work awesome.

Make sure that you remove the resistor pack if you have one and go with newer injectors.

I have a set of good working  (when I pulled them to replace with 630cc EV14's) Red Top 460's your welcome to have if you like.  I ran them on my F2T MX-3. Just sitting in a ziploc bag taking up space.

In reply to dansxr2 :

Thanks for the offer, but I ordered a set of RX8 yellows...... yesterday and on the recommendation of my dyno guy and the Adaptronic guy. 

On the incompetence side of things at least with this project, I seem to have finally found people that do actually know what they are talking about. The dyno guy I chose was a recommendation from Mazda605 after hearing about the shop,  WankelWorks (WW). So based on that I was fairly confident WW would be a good choice, while talking to them, it was brought up that he was bought up by a local race shop, that I have known for the past few years buying take off SM7s from their suspension guy. When speaking to the Adaptronic rep in Minnesota he asked about who my dyno guy was and knew of WW and confirmed WWs good reputation. Then just a few days ago we discovered that Mazda605 knows the owner of the race shop, another bonus as the owner is a fellow rotorhead, so I think I am in really good hands for getting the fuel system sorted out. Not to mention that once again GRM came through with pertinent information and I found new sources for the stuff I need. Thanks to all who replied. 

And Happy Mother's day to any moms out there. For those of you who are not Mom's,  call yours today and tell her you love her and thank her for all she has done.

1000cc/min is more than enough injector per rotor for anything naturally aspirated, on gasoline.  Mazda went way overrich to save the cats.

(Street ports need more injector than bridge or perpheral ports, HP to HP, because bridge/peripheral are far more efficient at max HP, almost into Diesel territory for BSFC. But street ports also make a lot less power, so it balances out that 1000cc/min/rotor is the most any N/A will need)

I've made close to 240hp at the crank on GSL-SE injectors (680cc at 2.5bar) but this was with Megasquirt.  Mazda computers seem to have a 70% duty cycle max, which is why I wanted to know what computer you'd be using.

The RX-8 secondaries sound like FC N/A regulars.  Way overkill for any N/A...

In reply to Knurled. :

So if I understand you,  the 2 x 460cc injectors per housing are still too much and I should look for something around 340cc per injector to land around 680cc total per housing. Are the GSL-SE injectors like unicorn tears as they were a limited model? 

Will the new ECU be able.to greatly reduce flow of the injectors through programming or even though we can control the signal it will still be squirting too much fuel?

Two questions.

I have been looking forward to getting the new fuel system installed, the last components arrived last night, the injectors. Typical for me I F'd up something and my injector connector is not the same shape as the new injector's.

The age old, how to fit a square peg in a round hole? Do they make and adapter for this? Maybe it is not hard to get the correct end and change my connectors? Or did I simply order the wrong part? I thought I asked all the right questions of my dyno guy and the people I bought my stuff through.

I also have a new fuel pressure sensor that I can't seem to find where it would be installed. It has a male thread about  1/4" NPT (I know, will/should be metric but I never learned metric, get off my lawn) Is there a port some where I am missing? Can't find anything in the FSM and looking under the hood I don't see where there is anything in the fuel rail where it could go. Is it maybe buried underneath the intake and I'll see it when I start removing stuff?

Thanks

I think this would do it. RX7 are EV1, RX8 are Denso connectors. 
https://www.bmotorsports.com/shop/product_info.php/manufacturers_id/9/products_id/774

Fuel temp sensor... not sure on that either. 

imgon said:

In reply to Knurled. :

So if I understand you,  the 2 x 460cc injectors per housing are still too much and I should look for something around 340cc per injector to land around 680cc total per housing. Are the GSL-SE injectors like unicorn tears as they were a limited model? 

Will the new ECU be able.to greatly reduce flow of the injectors through programming or even though we can control the signal it will still be squirting too much fuel?

I thought you were running four injectors for 4x460.

GSL-SE are weird in that there are two different injectors, the common 680cc injectors and the less common late '85 720cc injectors.  I don't remember what the external difference was, but I did have a friend who had quite a few -SEs over the years and he would send in the injectors and there were definitely two different subspecies.

Mazda did not run fuel pressure sensors.  Maybe they did on the RX-8 but certainly not on RX-7s.

In reply to Knurled. :

You are correct,  I will have 4 x 460cc injectors in total, 2 per rotor housing. 

The guy from turbo source had mentioned that if I didn't use the fuel pressure sensor it could be used for an oil pressure sensor. I thought that was odd, because how will oil pressure effect the fuel delivery system?

In reply to RXBeetle :

Thanks for the link, that is just what I hoped was available. I knew I could count on GRM.

All the parts are in and the engine started,  yeah! Had a friend help with basic programming and its time to make an appointment for the Dyno . Should be ready to get back out on the track in another week or two.  Thanks to everyone that provided ideas and information,  it is great to have a resource you can count on.