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Thread: How to compensate for larger injectors?

  1. #11
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  2. #12
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    Quote Originally Posted by Meshanic View Post
    Ok got mine right where I want it. Pulled 100 usec from the pulse width as my latency, pulled my desired percentage and then put 100 usec back in. 37.5% worked great for my 60 overs. Once I got that it all started coming together nicely. Using the Josh H timing calculator made timing a breeze. Just used the same strategy I've been using for years with the new pulse width numbers.

    I am loving tuning this thing! My street tune never exceeds 15' of timing & runs high 13's on a single CP3 with no lift pump. I have WAY less rattle than an LBZ with an edge. There is nothing like custom tuning
    I'm curious how you're using the timing calculator with the bigger injectors. Maybe I'm missing something here, but would you be willing to share your formula?

  3. #13
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    Quote Originally Posted by Zorganov View Post
    I'm curious how you're using the timing calculator with the bigger injectors. Maybe I'm missing something here, but would you be willing to share your formula?
    Injector size has no effect on the timing calculators accuracy. you just need to modify your base timing to work with your bigger inejctors(take some out in the mid to top end, but add some in at idle), and then use the calculator like normal.
    1995 GMC 2500 SUBURBAN powered by 01 DURAMAX/ALLISON, little of this, a little of that,
    DIAMONDEYE 4" exhaust, CORSA muffler, AFE stage 1 dry filter, custom tuning by me, KENNEDY single pump and pump rub kit.

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    The more I learn, the more I realize I have to learn still. I was under then impression with the latency you fellows were talking about, it would play into the timing via the pulse width. i will devote more thinking/learning time to the matter. Thanks THEFERMANATOR for your insight once again.

  5. #15
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    I believe the "timing calculators" are being mentioned due to the shorter pulsewidth that a larger injector will have for a given commanded fuel value. Thus, if your old "stock" injectors were at like 2000 us and now your larger ones only need say 1200 us to inject the same amount of fuel .... then you should be able to reduce your timing value to try and center up where your start of injection and stop of injection are occurring. So people have mentioned shooting for like 50/50 split (degrees BTDC ... degrees ATDC).

  6. #16
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    Latency is pretty constant from stock to oversize inejctors, and is used in figuring out your modified pulsewidth's for oversized injecotrs. It has no bearing on timing or the calculators as they use RPM, pulsewidth, and rail pressure to figure your timing to obtain a certain amount of injection before TDC.
    1995 GMC 2500 SUBURBAN powered by 01 DURAMAX/ALLISON, little of this, a little of that,
    DIAMONDEYE 4" exhaust, CORSA muffler, AFE stage 1 dry filter, custom tuning by me, KENNEDY single pump and pump rub kit.

  7. #17
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    I'm looking to do this for a friends truck who recently put in 30 overs. Where did you adjust the 37.5% in table? I was told to do like 22% at around 160mpa and starting at 1200us. And idle to only reduce around 5%. So did you reduce 37.5% on the whole table? or just the upper areas?

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