I plan on using a 4 720cc or 750cc injectors, but not sure what I need as far as configuration is concerned. I will be using the Series 4 TII ecu from an 1987, it's an N332. I believe I need High Impedance, but since this is a different ecu, I don't know if they need to match it.

 

if i recall correctly, the N332 ecu uses low impedance injectors with a resistor pack.

the 720cc injectors should be fine, but you'll need something to tune your fuel. without it you'll probably run rich.

im sure someone else can chime in on what to use for tuning fuel. I'll mention the SAFC to hold you over until somebody else can give you some additional info.

 

I already plan on using the Rtek 2.1.

 

in that case, 4x720cc low impedance will work fine since the rtek has presets for 720's.

if you want to be absolutely sure whether or not what type of injectors you need, check by the passenger side headlight. if there is a resistor pack (silver box) there, then you need low imp. if not, then high imp.

 

Does it matter what kind of low or high impedance top feed injectors I get? Are they all the same in that configuration?

 

when you are Looking for injectors,just List the application that it is being used for.The companies usually list what injectors can be used on the RX7.
usually a Denso type injector,Top feed.
You can get injectors that will Plug and play into your Harness,But If you want to go with another type of Connector,then that will involve Cutting them off and splicing new ones onto your harness.
Try www.kgparts.com
www.injector-rehab.com
www.rcenginering.com
those are some sites that sell good injectors.

 

Any recommended places to get injectors? Also recommended brands, bang for the buck? locations on the net?

 

http://osidetiger.com/Polished.aspx

resistor box for $40. Polished hotness. That is if you need one and dont have one and want to bling out.

Same place used to have 850's and 680's (i bought some stuff from here a few months back) but i can't find em. If i were you, i'd run MORE secondary than that. Maybe 1000's. You can always manually lean them out with the rtek. That's what a wideband and egt is for. I'd rather have too much fuel than not enough. Remember, you're playing with high compression. Boost creeps up on ya and it could cost you an engine.

 

I've decided to use Injector Dynamics, good prices. But anyways I just started using the calculator on rx7.com and it says that 550cc/725cc injector setup at 80% duty cycle will be good for up to almost 300 hp. Is this correct? It says if I use too large for primaries I'll have overly rich idle, which I do not want. If I have too rich for secondaries, I'll have stumble around 4000 rpms. Will this be a problem if I am going to be using the RTEK 2.1?

 

http://www.turblown.net/store/index.php?productID=75

 

Injector impedance has nothing to do with the ECU. All you need to be considering is what harness you have. If your harness uses the resistor pack ('86-'87.5), you should use low impedance injectors. If it does not, then use high impedance injectors or low impedance + resistors wired in. It's really just that simple.

What turbo are you going to be using? Stock turbo? If so, you don't need anything more than 720cc secondaries. 550/720cc is one of the Rtek presets, so you won't even necessarily need to adjust fuel. I would definitely adjust timing however. Go to the Rtek section and and take a look at the timing maps arghx has posted. MAP based timing will give you the flexibility to keep a high compression turbo engine alive.

 

Hmmmmm... well the turbo I will be using is close in size to the GT35R, maybe a little smaller. It's a Holset WH1C turbo from a 94 Dodge Diesel truck. I will probably have to go with 1000cc injectors. If I use the map based tuning, do I use the stock turbo map sensor?

 

A GT35R is fairly large, so something like a 720/1000 combo would be better. Keep in mind that 1000cc injectors are basically the largest you can run on an Rtek 2.1. Fuel can only be adjusted +-37%, which happens to be about the difference between a 720cc preset and a 1000cc injector. There are a number of people using this injector combo with Rteks and hybrid turbos.

It's not MAP based tuning, but rather MAP based timing that I was talking about. Fuel delivery is already MAP based, but timing is determined by a LOAD calculation. LOAD is figured from MAP readings, RPM, AFM measurements and maybe some other things. If you switch over to MAP based timing (instead of LOAD based), you will have a much safer setup with high compression & a turbo that is vastly different from stock. It will behave more like a standalone EMS. And no, you cannot change any sensors from stock. You will be limited to measurements 1 bar (14.7 psi) and under from the stock MAP sensor.

 

From what I am hearing, I am able to use the S4 Turbo sensors and ECU with my S4 RX7 vert, since there isn't a problem there I will be able to use the turbo MAP sensor, although I think I may be misreading your statement. Anyways I'll be using the all S4 turbo sensors with an S4 turbo ECU with RTEK 2.1 installed. After that it is all about picking the injectors I will need to use, which means choosing a power goal correct? So if I am going after the target range of 250-300hp, which is decently wide range when I think about it, using 4 720cc or 725cc in this case (Injector Dynamics), at 80% duty cycle according to rx7.org calculator, that put's me at around 294hp. Either way, as I see it, I am limited by the injectors I use as to how much boost I can run safely. Is this all correct?

 

Yes, you are correct. All sensors need to match the ECU. If it's an N332/333 S4 TII ECU, all of the sensors also need to be from an S4 TII.

Using Howard Coleman's calculations here: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/feeding-turbo-rotary-horsepower-airflow-fuels-881992/, Four 720cc injectors can support roughly 340 whp @ 85% d/c & 11:1 AFR. But it's likely your turbo will be capable of a little more, and you may not end up at exactly 11.0 AFR. So, as you mentioned, fine tuning the boost level will be critical. You'll just have to start low, and work your way up slowly.