Nistune K-Constant Thread

1 2 3 Next
  • #1

    Nistune K-Constant Thread

    Nistune/Injector K-Constant Reference Table:

    M: make/model/colour/nickname
    C: capacity cc (unless other unit of measurement specified)
    F: base fuel pressure (assumed factory 30psi at 0 vac unless specified)
    K: k-constant value (k)
    L: latency (us)
    I    : impedance (high-z/low-z)
    N    : notes (short mod list, other fuel components)

    --------------

    M: Mazda
    C: 460cc
    F:
    K: 390
    L: 800
    I:
    N:

    --------------

    M: R32 GTR Skyline
    C: 440cc
    F:
    K: 343
    L:
    I:
    N: stock FPR

    --------------

    M: DSM (no colour specified)
    C: 450cc
    F:
    K: 143
    L: 770
    I:
    N: stock FPR, walbro fuel pump, cobra maf

    --------------

    M: Mazda FC3S RX7 - Denso
    C: 550cc
    F: 37psi
    K: 330
    L: 750
    I: Hi
    N: mostly stock 88 tune, stock fpr/lines/maf/pump/turbo (at 14-15psi), 3" exhaust, stg1 schneider cams

    --------------

    M: Ford Green Tops
    C: 440cc
    F: 37psi
    K: 119
    L: 57
    I:
    N: Ford Lightning maf, walbro pump, aeromotive fpr, 24* base timing.

    --------------

    Keep 'em coming…

    Original Post
    wrote:
    does it make sense to start a small table of k-value in reference to injector sizing for starting the car to a reasonable idle- or is it really something better left to repeated testing? not sure if constant flooding of the car trying to find proper values is a good way to go about it.

    I was searching for terms like 550cc and k-constant, and I get differing threads about for sale items and just general nistune witchery…

    I was wondering if instead of using the "percentage" or math formula that people run with if posting the injector size and fuel pressure along with which maps were initially loaded would be a good way to hone in on better first-time start ups with new injectors.

    It crossed my mind because I think my issue with misfiring is a lazy or drooling injector… so I was going to get 550cc's but I'm unsure if it's even safe to tune a 550cc injector on a basically stock motor/turbo instead of getting another set of janky oem replacements for like the 90th time.

    I'll be getting rails and a forward facing intake, but if I'm going to pull my current intake- I want rails and injectors now… so 450 or 550 is probably what I'd go with.
  • #2
    On my 460cc mazda injectors Ive found 390 works pretty decently.
    Running 800us of latency as well.

    EDIT: They are also low imp, ~4ohm IIRC
  • #3
    I'll let you know the values of when the 680cc rx7's work when I get them up and running within the week.
    Usual Z31 suspect: Garage Queen (aka broken)
  • #4
    R32 GTR skyline 440cc injectors seems to like 343 using the stock FPR
    85 Turbo Slick Top
    __________________________________________________ _____
  • #5
    1
  • #6
    450cc dsm
    k- 143 currently
    latency- 770
    stock FP with walbro and cobra maf.


    Edited the latency.
    Hmmm, Whats next?
    Full Size Bronco, smashing shit.

    84ZXT
  • #7
    Bernardd wrote: There are a couple of issues with trying to or expecting to have a one time k adjustment. You probably know this but injectors may be rated for the same flow but they may have vastly different opening times. So if 500cc injector A opens at 520us and 500cc injector B opens at 800us you will have a large difference in fuel flow when total injection time is only 2ms or less. You also have different fuel flows from pumps due to age, system voltage as well as the maf setup skewing afr's from what you might be commanding. Does your water temp sensor read exactly what is expected with it's age or is it perhaps an aftermarket part. If you suspect an injector a fresh set of plugs and a few minutes of idling will tell if the cylinders are running equally or if one is rich by pulling the plugs for a look. Now that I think about it, the first time injection table should be adjusted by old inj/new inj and the opposite is true for both cold start enrichment tables. You may know all this stuff but some newbie to nistune might find this helpful. I know that even after 11yrs of mucking around with nissan ecu's I'm still learning new stuff all the time.
    I understand. Even the stock fuel maps are programmed well enough to work in different climates and temperatures and whatnot- so it's anyone's guess. But as you can see- there are some people who have the data on hand, so putting it all in one place makes searching easier if the size-up percentage formula with new vs. old doesn't work out for someone. Not me being lazy, just me wondering.

    lets keep this going?
  • #8
    it's amazing how the 440 and 460 injectors differ so much from your 450 settings, shromy.

    for this reason- i think exploring other people's input is what makes this thread have at least a shred of value to some of us.
  • #9
    yeah totally different, almost the same k I used with my crappy old MB 420's. The car ran better with the 450's at the same k then the 420's. Course that was due to the one failed injector that cost me yet another piston.


    Yes lets keep this going. Are bin files up-loadable?

    Edit no they are not .
    Hmmm, Whats next?
    Full Size Bronco, smashing shit.

    84ZXT
  • #10
    so… does it need to be mentioned whether they are High-Z or Low-Z injectors?
    no reason to upload bins- this is merely a starting point.

    edit: do we also need to mention the "minimum pressure" required for the injectors listed?
    I'm seeing a lot of them are 36psi minimum. infact- most of them are… how are they even running properly with our cars?
  • #11
    Hmm, never seen if the figures would change in an ohm difference since I have always used low ohm.

    I dont think the min. pressure is that important. Since most users will be on stock fuel setup, maybe with an aftermarket pump. The other half simply wont know what it is.

    I suppose both would not be a bad thing to add. I think you should setup a list in the OP so it can be found easier instead of searching 20 posts etc, IMHO.
    Hmmm, Whats next?
    Full Size Bronco, smashing shit.

    84ZXT
  • #12
    I'm running a mostly stock 88T tune with s5 fc3s rx7 550cc injectors (hi imp)…stock fpr and fuel lines…stage 1 schneider cams, full 3" exhaust, factory turbocharger at 14-15psi, 87T MAF, stock fuel pump

    K = 330
    lat. = 750

    runs great!

    1987 Nissan 300ZX Turbo (Budget Supercar)
    1987 Nissan 200SX SE (Old School FR)
    1994 Nissan Sentra SE-R (Balls To The Wall Track Car)
    2000 Nissan Maxima SE (Daily Driver)
    2006 Scion tC (Wife Whip)

    In an ideal world I would have all ten fingers on my left hand, so my right hand could just be a fist for punching.
  • #13
    Ford green tops 440cc, ford lighting maf, walbro pump, aeromotive fpr, set 37psi at idle.
    K-0119
    latency-57
    24' base timing
    Runs and starts great!
    88na2T-s13,q45 swap 12.6@110mph
    87T 2+2 auto,stock
  • #14
    shromy wrote: Hmm, never seen if the figures would change in an ohm difference since I have always used low ohm.

    I dont think the min. pressure is that important. Since most users will be on stock fuel setup, maybe with an aftermarket pump. The other half simply wont know what it is.

    I suppose both would not be a bad thing to add. I think you should setup a list in the OP so it can be found easier instead of searching 20 posts etc, IMHO.
    will do when i get home.
  • #15
    shromy wrote: Yes lets keep this going. Are bin files up-loadable?

    Edit no they are not .
    If anyone wants to share BIN files I will host them on my site and post them here, just e-mail me them.

    Z31NA2T (at) rochester.rr.com
    - VG30DET (HE341) 86 300ZX - 1982 280ZX Turbo - Headered NA 1986 300ZX 2+2 - 2000 Xterra -
1 2 3 Next