fc1jz

Doing a single turbo conversion, so I installed my fuel system today. It consists of kgparts secondary rail, ss braided fuel lines, and aeromotive rr fpr.
The rail and line kit fit perfectly, but this is what I had to do to make the injectors fit into the Lower intake manifold:
I removed the LIM for ease of working and so I wouldnt get **** in the motor.
I found the factory plastic shity diffuser pieces all but crumbled. I stuck my finger in the secondary port on the LIM and pushed the diffuser up through on each side. Of course they broke into tiny pieces. They were held in with used-to-be-rubber orings
I have read that people usually retain these when using the 1600's but just cut and smooth the 3 legs on each diffuser, and remove the yellow cap (or file the lip away) No way I could do that.
So instead of running to the mazda dealership and ordering new diffusers, I took a trip to the local advanced autoparts store and got a fuel rail o ring kit. Part number 800-9211.
Inside the kit there are 4 identical o rings. I took one of these o rings and pushed it over the yellow cap on the injector (nozzle end of course), over the blue o ring that was already on the injector, but not over the spacer. The new o ring was basically wedged between the spacer and the blue o ring.
Doing this allowed the injector to seal perfectly inside the space previously filled with the plastic diffuser. I also didn't have to modify the injector or the manifold in any way (other than removing the diffusers).
Then I did the same thing to the other injector.

So hey cool, I got them in. Now I have a question, do I need to run resistors for these injectors??? I got the injs from rx7store. Also is there any particular way I have to wire the injectors, like make sure black wire on injector harness goes to the factory wire with stripe, ect????

CCarlisi

The general opinion is that they need resistors, at least with a PFC. However, there is an EE in OR that uses 1680s w/o resistors on a PFC. He apparently found their behavior with resistors to be a little funky at high duty cycles when they heat up and stable without them. This is third hand information though so I wouldn't rely on it.

As far as resistor type, I believe Steve Kan recommends 4 ohm and KGparts uses 10ohm. http://www.3rdgenrx7.com/keithshowto.htm

spoolin93r1

i'm thinking my resistors are 10ohm that i picked up from radio shack

pp13bnos

iTrader: (1)

I know that Ralph Friend at Groundzero motorsports runs his cars without resistors too. (Xcessive on the forum.) Not shure if this is who CCarlisi is talking about or not...but I'm guessing it is. CJ

fc1jz

Thanks CCarlisi that link is exactly what I needed. Ok, so 10ohm 10watt resistors.

Anything else I should do before hooking this up???

fc1jz

damn you posted this right when I posted.

Anyway, are the resistors just to help with voltage fluctuations to the injector? Or is it more in relation to its impedence. (sorry, don't know a lot about injectors yet)

I would rather not run them if I don't have to.

I want as few electrical connections as possible, especially when involving the injectors.

NewbernD

iTrader: (1)

The resistors are to protect the injector drivers in the computer. Depending on the computer and what it's expecting you may run the risk of burning out the components by running too much current through them.

Interesting solution to the LIM injector fitment problem. Here's what I made to make it work:



More info here: Injector Bushings

CCarlisi

Very nice, I just ordered a set from you.

my-sons rx7

Sweet wish we knew about them when we did are's.

CCarlisi

It doesn't take long to get down to the secondaries (the primaries are a different story :-p). I see it as a good opportunity to do a little visual inspection

fc1jz

By the time you get your UIM off, you may as well take the lim off. Doesn't take much longer (I do have block off plates though) and it gives you a good chance to clean and inspect everything.
I always feel good about taking **** off and putting it back together on my rx7. I know this car has been disassembled and reassembled many times (as most of ours have), and I just like knowing that I was the last person that put it together.

OzFeTt

the only problem with using resistors is that they slow down the response of the injector. This may be what ccarlisi is referring too. I don't know of any way around this other than to find suitable high impedance injectors or use a different computer which is low-impedence stable. Having said this I run 1680's with resistors without any problems. I think it would only be a problem at very high 85%+ duty cycles which is a lot of fuel even for a high power 13b!

RX794

You DO NOT NEED to use resistors with 1680's(Me and about 5 other people I know, including Ralph from Ground Zero don't use them), because if you test the resistance of the 1680 injector(I say it's a 1680 because a 160lb injector equals 1680cc's NOT 1600cc's) is about 5ohms with no load, as load grows, so does the resistance in the injector, this is not considered a low impedience injector because of this, also using resistors slows the injector response down, as well as sometimes making the injectors surge during long wide open throttle runs, more info can be found here:
https://www.rx7club.com/showthread.p...hreadid=255008

the_glass_man

iTrader: (2)

How many people run that setup without resistors?
I know KDR was setting up cars without them for awhile.

fc1jz

Damnit I wish you posted this before I decided to go sauder in resistors. Oh well, I guess I will just clip them out and reconnect.

fc1jz

By the way, I just updated my avatar. That is my car. Except now I have a CF hood.

gfelber

This mod rocks. I've been using these for a couple of months now. Install info here: http://www.mantissaracing.com/Mantis...uel_system.htm


Thanks again Dave!

Gene

finnicky7

Dave I sent you a PM, I think I will need a set as well.