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When Does VTEC Kick in?

As I recall, VTEC operation is not just RPM dependent. It is also engine load (MAP) dependent. You probably need pedal to the metal in the lower gears to get the MAP high enough to engage VTEC
 
Unless you have aftermarket cams, the changeover to VTEC on the NSX is imperceptible. Honda worked quite hard to make it this way, since the NSX is a "premium" luxury car. On the NSX, you have VVIS engaging around the same RPM. Most people who think they're hearing VTEC kick in 'yo are actually hearing VVIS, which changes the torque band and intake sound of the engine around 5,000 rpm.
 
Unlike the AP1 S2000 where the VTEC kicks in hard at 6K (of 9K) revs, the early NSX threshold is lower.
From personal experience, I'll go out on a limb to say that our 1992's hit VTEC around 5800rpm.
But like HONCHO said, the transition was meant to to be intentially smooth in the NSX.
 
If I remember correctly VTEC activates around 5750, right where torque and horsepower curves converge. However VTEC can engage lower or higher dependent on aftermarket ECU's and tuning. On my low compression FI setup I have VTEC set at 5250 and that is where my horsepower and torque curves meet. But I'm also at 440 ft/lbs of torque and 525 rwhp so your numbers may be different.
 
Unlike the AP1 S2000 where the VTEC kicks in hard at 6K (of 9K) revs, the early NSX threshold is lower.
From personal experience, I'll go out on a limb to say that our 1992's hit VTEC around 5800rpm.
But like HONCHO said, the transition was meant to to be intentially smooth in the NSX.
OEM tune is VTEC rpm threshold of 5,800. There may be some hysteresis around it, @MotorMouth93 would know. If so, it could be a little higher or lower than 5,800 depending on other factors.
 
Is it also because there is less intention of economy vs the smaller B series engines of the era which were designed as good mpg + "racecar cam profile". I haven't checked the lift and duration differences but I always assumed the 'crossover' was just also less prevalent because the small cam lobe was larger.

I do agree that it's load sensitive (at least the VVIS is) as slowly rolling through the rpm range sometimes has no noticeable sound change compared to flooring it. We do have pretty standard VTEC solenoids also which means oil temp/level will likely affect it also.
 
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