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Thread: 120HP Injectors and RPM limit

  1. #1
    Tuner in Training
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    Nov 2018
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    120HP Injectors and RPM limit

    After saving up for awhile I finally ordered new Bosch injectors with 120hp nozzles, 103lb valve springs, head studs, and a second gen swap with the s464 turbo. First question, what do I need to change in the tune for the 120hp injectors? Obviously pulsewidth needs to go down, but should I take some off the whole table for the larger nozzle or just off the top end? Second question, what kind of RPM can I turn with the 103lb valve springs? Im a fan of the Hard Limiter sound, with the truck stock ive been running it anywhere around 3200-3400.
    2004.5, built 48re, Fass lift pump, K&N cold air intake, 461hp 916ftlbs

  2. #2
    Advanced Tuner
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    Not really necessary to knock duration off the entire table but peak duration will be around 2700us or so, not sure on the rpm limit with those valve springs.

  3. #3
    Tuner in Training
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    So how do you determine peak duration for a bigger injector? In my hot tune for stock I?ve got it up to 3200Us. I understand it flows more fuel, but why shouldn?t you run the 120hp nozzle at 3200Us? Also, what kind of rpm are stock CR rods good for?

  4. #4
    Advanced Tuner
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    Jan 2018
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    With larger injectors at a point the flow exponentially increases over stock flow as pressure increases and duration increases. You?ll find you will not need as much duration to get the most you can out of the setup up top. Max fuel for max effort tuning will be dependent on the air that can be flowed into the engine as well.