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When Should Vtec Kick In?

Discussion in 'ECU's, Electronics, and Tuning' started by RFHOMI2U, Feb 9, 2003.

  1. RFHOMI2U

    RFHOMI2U Senior Member

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    I have the rpm switch set at 4000 on my d16z6 for the vtec to kick in. Is this too early? I was told by a friend it should be at 5200. Is it a bad thing that it is coming on too early? or is it actually better?
     
  2. pills_PMD

    pills_PMD Super Moderator

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    on my d16z6 i had it set at 4500 rpm.
     
  3. Havok

    Havok Senior Member

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    :werd::withstupid: 4500 sounds good, 5200 is kinda high, and 4000 is too low--you don't want it to activate right before you shift.
     
  4. GSRCRXsi

    GSRCRXsi Super Moderator Moderator VIP

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    mines set somewhere between 5500-5800, i thought it was better to have it high, b/c i thought vtec is better at higher rpms, and not low. hence the need for variable valve timing in the first place. maybe its just my engine?
     
  5. JrSiRb16A

    JrSiRb16A Senior Member

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    yeah i got B16A..mine comes in like round 5000 rpm..which is good..
     
  6. S13Less

    S13Less Member

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    oye... sheesh... ok. THE reason why you have vtec is to make more high-rpm power (without sacrificing gas-sipping driveability and quiet idle) ... ever heard an old muscle car with performance cams? it sounds very rumbly, and they can barely idle. VTEC is basically having two sets of cam profiles in one... the first set is for normal driving and the next for spirited driving.

    Wanna know how to get the most out of your vtec? Have a way to adjust the vtec point first (ex. Apex'i V-AFC) and go on a dyno. First have it set really high like 1000 before redline and do a run... then run it again with the vtec activation point really low like 3500. Print out both dyno runs... the OPTIMAL vtec activation point is where the two different graphed lines intersect. Get it? This will provide the most power overall because at some point (in lower to mid-rpms) the non-vtec side will start making less power than the vtec side and that's where vtec should kick in. The "bigger" side of the cam(s) will not always make more power... it takes rpm to do that, so find it.

    Oh yeah, I forgot most of us don't have easy access to a dyno. So for those of you out there in that case, Aries Dizon of Dynamic Autosports, who has been in dozens of magazines for his tuning prowess suggests 4400.
     
  7. sleeperls93

    sleeperls93 Senior Member

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    To work on the lower cam profile, you set the vtec crossover point at about 7k rpm. You adjust the a/f curve to fix all the dips in the graph; after that you do another pull on the dyno. You observe where the tourque starts to fall-off, the start of the tourque drop would be the ideal spot to set the vtec crossover point.
     
  8. pills_PMD

    pills_PMD Super Moderator

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    i've got mine set on 4400 on my b16 when i am going to the track... otherwise for daily driving, i try not to engage the high cam profile all that often as the CTR cams and my hondata map like to guzzle gas when they are engaged. so i sometimes crank the vafc up to like 5500 for driving around town or for expressway driving
     
  9. B16

    B16 Super Moderator VIP

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    mine was set at 5000 per the dyno of my car, however, when i put on the 64mm TB, it seemed to stutter at that vtec x-over, so i put it up to 5500 which feels the best for me so far. i need to get the car on the dyno again, after doing TB, intake mani, and now i have an adj. fpr. i have a b16 using CTR cams and springs/retainers. pills, you dont find the 4400 xover to be too early?
     
  10. pills_PMD

    pills_PMD Super Moderator

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    not at all.. i have my intake cam 2 degrees and my exhaust cam -2 degrees and the low end really drops off drastically after 4500 i mean if the vtec is set higher like 5000 you can feel a huge dip then it pulls very hard once the vtec kicks in... i plan on dyno tuning after the winter because i am getting some work done on the head. but the ass dyno says that 4500 is pro.
     
  11. pissedoffsol

    pissedoffsol RETIRED

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    where's the best place? dyno it.

    thread done :)
     
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