FIC larger injectors to be used with Nistune? As well as a few other qustions.

  • #1

    FIC larger injectors to be used with Nistune? As well as a few other qustions.

    Hi Everyone,

    After some time away from my 1986 Z31 turbo project, I've decided to take it to the next level of the build. I've made significant upgrades to the car including turbo upgrade, exhaust, fuel pump and regulator, intercooler, electronic boost controller, external wastegate, clutch, flywheel, LSD and a number of others. Now it's time to bring my ECU and injectors up to par. The fuel rails I will be using were purchased from Jason a few years ago and are the 11mm o-ring style.

    My good friend has a 1994 sentra with a bluebird sr20 in it and he is using Fuel Injector Clinic (FIC) injectors with much success. He was very impressed with their customer service, product and performance which is why I'm leaning in their direction.

    I have a few questions:

    1) Is anyone using FIC injectors on their Z31? If so, what are your experiences with the product and what injectors are you using?

    2) I've been doing some reading on impedance. I know that my 86t uses a low impedance ECU as well as low impedance injectors. After reading this article: http://redz31.net/pages/fuel.html it seems as though using high impedance injectors on a low impedance ECU will work fine - Low impedance ECU driving a high impedance injector should operate normally. - Is this true?

    With that said, are there any negative consequences of using high impedance injectors with a low impedance ECU? Seeing as how both high and low impedance injectors are available, which injector is the better choice for my application?

    These are the injectors from FIC that I was looking at:

    High impedance - http://fuelinjectorclinic.com/350z-g35/IS186-0775H
    Low impedance - http://fuelinjectorclinic.com/nissan…b26/IS185-0750

    I noticed that these two types of injectors are slightly different in shape. Will both styles work with our vehicles?

    3)Lastly, my z31 has the injector re-wiring campaign done around 2002. Will i need to re-wire my z31 to pre-campaign wiring in order to use Nistune and my new injectors properly and without issues? I did some searching and I couldn't find a clear answer. Is getting the injector wiring back to what it was before the Nissan injector campaign essential when upgrading the ECU and injectors?

    one other note, my HP goal is about 350-375. Knowing this, and after doing some reading, it doesn't seem as though I need to be using a Z32 MAF with the Nistune upgrade. Are there any advantages to using a Z32 MAF even though my goals don't exceed 400+hp? Engine response, durability/longevity, ect?

    I know, lots of questions. If any of you can provide any insight on the questions above, it would be greatly appreciated.

    Thanks,
    Remo
  • #2
    Injectors, ideally you want to use the impedance that matches the ECU you are using. They have a different opening speed, that will cause the timing to be off. While not a huge issue, some people state it causes issues tuning for perfect idle etc.

    Fitment, as long as the injector fits the opening/o-rings you have and the fuel rails, you should not have an issue. As I am not using upgraded injectors, I am not sure if Jason's fuel rails act as an injector mount (OEM injectors have a bolt on piece near the middle that allows them to maintain correct mounting and no leaks).

    Pre vs Pos injector campaign - You don't HAVE to wire them back, but most people do as. I do not believe it will have a huge effect on the ECU load when using a low impedance driver. Due to needing dropping resistors, it is preferable for high impedance ECU's to make life easier.

    Z32 vs Z31 MAF, you can use the Z31 maf with some mapping changes, however it means the ECU extrapolates the data, whereas the z32 MAF has better resolution for air flow. While this may not have a big impact, it is again a personal/monetary preference I believe.

    I hope this information is correct, I like to read alot on the forums and this is information I have picked up.
  • #3
    The injectors for vq engines which is what you appear to have posted use 14mm top o-rings and use uscar connectors, you'd be better off going with siemens/deka high-imp injectors with the same ev1 connectors we use…
  • #4
    Originally posted by G-E
    The injectors for vq engines which is what you appear to have posted use 14mm top o-rings and use uscar connectors, you'd be better off going with siemens/deka high-imp injectors with the same ev1 connectors we use…
    ^ This, at least for the high impedance injectors you listed. If you look a them, they are using a different injector connector, so you'll have to get new pig tails and replace all of your injector connectors. But as Windzer said, though high impedance can work on a low impedance ECU, if you have the choice, get the set that matches your ECU. That set of low impedance Skyline injectors looks like it has the correct connector. Also, as G-E mentioned, all of those run the o-rings on the top that are designed to plug directly into a fuel rail, vs our injectors that have the barb style top. Though you can get a piece of hose and shove it down over the top, it's not ideal. Since you mentioned redz31, I'm assuming you saw this page which discusses that: http://www.redz31.net/pages/fuel/fuel.injectors.html

    You could also look at Mistubishi injectors. The DSM and turbo 3000GT used the same style connectors as our cars, and were both also low impedance.

    If your goal is only 375-400hp, why are you looking at such large injectors? If I were you, I'd look at some cleaned and flow tested OEM 550cc RX7 injectors. Contact [email protected], he'll hook you up. Me, my brother, and a couple friends have all had great experience dealing with him. A friend just got a set of 560cc injectors from him for around $240.
    Prius… because Pretentious wouldn't fit across the back of the car…

    Cheap, Fast, Reliable - pick any two

    My 1986 Turbo Build
  • #5
    Actually, I talked to Allen (EvolutionInjection guy) yesterday, and he's getting out of the business of selling them and is just servicing them. I just got lucky in snagging one of the last sets he had, but maybe he has one or two left.
  • #6
    Originally posted by z car go
    Actually, I talked to Allen (EvolutionInjection guy) yesterday, and he's getting out of the business of selling them and is just servicing them. I just got lucky in snagging one of the last sets he had, but maybe he has one or two left.
    Well that sucks, guess I'll have to start looking for a new source for injectors.
    Prius… because Pretentious wouldn't fit across the back of the car…

    Cheap, Fast, Reliable - pick any two

    My 1986 Turbo Build
  • #7
    Hi Guys,

    Thanks for the feedback. I called FIC today and asked about compatibility with my 86t and my 11mm o-ring fuel rail. I was told they can accommodate me and make me a set of injectors for whatever application I want. Brian at FIC also said that there should be no problems using a high-impedance injector on my application, but I'm still hesitant.

    He's asked me to measure my stock injectors from top o-ring to bottom o-ring and also to measure the diameter of the upper and lower o-ring valleys. Seeing as how our injectors are barbed on top, I will just take those measurements with my caliper and send him some pictures and see what he says. The only one that should really matter is the top to bottom measurement, I think.

    I don't suppose anyone has that kind of size/measurement information off hand? I read on G-E's link at the bottom of his post (http://carfish.net16.net - obscure resources for 300zx owners) that RB26DETT injectors may work, but there is no fitment data listed on his site.

    Has anyone used RB26DETT injectors in our cars with Jason's style of 11mm o-ring style rails? If so, I have my answer.

    Thanks again,
    Remo
  • #8
    Hi Guys,

    I've been a bit busy but managed to speak to Bryan at FIC yesterday. So, it looks like the Nissan injectors may not be the best choice. I am now looking at these:

    http://fuelinjectorclinic.com/dsm-evo-1-9/IS126-0750 which are low impedance..

    Of these: http://fuelinjectorclinic.com/dsm-evo-1-9/IS126-0650H which are high impedance..

    Bryan told me that the high impedance injectors are newer and better technology and I should use them if I can. He asked me about removing my bank of resistors, but to my knowledge, my 1986 z31 turbo does not use resistors....Meaning the signal coming from my ECU is a low-impedance signal. Is this correct? and if so, he told me I shouldn't have a problem using the high-impedance injectors. He also asked me if Nistune is able to scale injectors. I'm not really familiar with Nistune…can injectors be scaled?

    One other question he had for me was about the lower injector seals that are in the lower intake manifold. When using stock DSM injectors, is it necessary to change out the lower seals? or can I install these new injectors using the stock lower seals that are in place (Or swap those out and use the ones that come with the new injectors, which I assume would be the same if folks are using stock DSM injectors with their stock lower seals. Using aftermarket 11mm fuel rails)?

    Again, always appreciative of your information and advice.

    Thanks,
    Remo
  • #9
    Nistune scales the injectors using K value. Bottom injector seals may or may not have to adapt to injector style. Could be skinnier/thicker on bottom vs. OEM injectors.
    Usual Z31 suspect: Garage Queen (aka broken)
  • #10
    Yes, the 86 ECU is a low impedance signal. You can do whatever you prefer, but personally, I would rather get the injectors that match the signal from the ECU just to avoid any potential issues that may arise from mixing and matching the impedance. As has been said, running high impedance injectors on a low impedance ECU should work, but why do it if you don't have to?

    Those are listed as being "DSM" injectors, so the dimensions should be the same as the OEM 450cc DSM injectors I'm running. Mine dropped right into the stock O rings and work fine, didn't need to change any seals.
    Prius… because Pretentious wouldn't fit across the back of the car…

    Cheap, Fast, Reliable - pick any two

    My 1986 Turbo Build
  • #11
    Thanks for the info guys! Much appreciated. I'll post pics and a follow up when I get the injectors and install them.

    Remo