VTEC engagement point
09-17-2011, 04:56 PM
#11
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The reason that the VTEC crossover is set at 6000 rpm is that at essentially that rpm, the torque curve from the high lift cam crosses above the torque from the standard lift (i.e., low rpm) cam. Let us give the Honda engineers credit for being able to measure that crossover point for the Ap1. The torque from the standard lift cam is dropping at 6000, although that decline is fairly gradual from 5000 rpm onward, while the torque from the high lift cam is rising rapidly. I have seen the curves. There may be a bit more excitement factor, and noise factor, from placing the VTEC transition a bit lower rpm wise, but there should be no performance advantage.
09-17-2011, 08:17 PM
#12
AP1's have shown gains from lowering Vtec as well... Although my old RSX was as Jelliotlevy said. My theory is part of why they raised the cam crossover (this is AP1 specific) to 6k is because even on the 1-2 shift at 9k it is very easy to shift quick enough to stay in vtec, in fact even a 8.5k short shift stays in vtec, so thats why no higher than 6k, then the reason i think they didnt go lower is because that kick is exciting to people, so 6k was the sweet spot of excitement w/o dropping out of Vtec on up shifts. Whereas on my RSX, you had to be damn quick to stay in vtec on a 1-2 shift at the 8k redline, so higher would not have been practical.
09-18-2011, 06:30 AM
#13
All S2000's come with a 6000RPM(some say its actually 5.8k) VTEC shift from the factory. If yours is shifting at any other RPM, then it is either broken or not-stock. Further, no pre-06 S2000 has a flashable ECU, so if it is ECU programming, either someone swapped to an aftermarket ECU, or there is a piggyback system hooked up to it.
My 2001 hits VTEC at the normal 6k, as does every other s2000 I have driven. (I've driven quite a few)
My 2001 hits VTEC at the normal 6k, as does every other s2000 I have driven. (I've driven quite a few)
09-18-2011, 06:39 AM
#14
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Gosh, I paid some big bucks for the hardware, software and the tuners's time to lower my VTACK engagement to 1000 rpm. The tuner tells me the dyne said I picked up 87.3 whp across the band. On the way home I got this odd feeling that the tuner was just telling me what I wanted to hear because of all the money I just gave him. If only I wasn't so stupid about mechanical stuff, I might understand what just happened. I wish I really knew how an engine works. I mean, if the engagement point is good at 6000, it's just gotta be better the lower it goes, right. I'd like to have it engaged right from even before the start button is pushed. Just think how much more drivable the car would be if it had 10 more HP while idling.
09-18-2011, 08:37 AM
#15
Originally Posted by bronxbomber252' timestamp='1316356218' post='20983558
All S2000's come with a 6000RPM(some say its actually 5.8k) VTEC shift from the factory. If yours is shifting at any other RPM, then it is either broken or not-stock. Further, no pre-06 S2000 has a flashable ECU, so if it is ECU programming, either someone swapped to an aftermarket ECU, or there is a piggyback system hooked up to it.
My 2001 hits VTEC at the normal 6k, as does every other s2000 I have driven. (I've driven quite a few)
My 2001 hits VTEC at the normal 6k, as does every other s2000 I have driven. (I've driven quite a few)
09-18-2011, 09:28 AM
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Well the information I got it from my tacometer and I bought my car in Colorado, its there anything wrong with 6500 vtec on a 2001 ap1 or it should be lower than that?? I asked the dealership and I was told by the dealershhip that the vtec activates at 6500 rpm and the ap2 at 6000 because ap1 red line at 9k and ap2 at 8k... Someone to confirm or correct this info, unless this is correct I guess someone messed with the programing...
I see Colorado in your first quote...altitude is what 7000' ASL (above sea level) VTEC is MAP & RPM dependent, if the air is too thin it will only engage at 6500 RPM...
Good read about it here VTEC window paragraph, the same logic applies to AP1 Hondata reflash
09-18-2011, 11:31 AM
#17
I think everything you've experienced is due to altitude. Shame on the dealership for the misinformation.
Scott-
09-19-2011, 01:39 AM
#18
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"An engine requires large amounts of air when operating at high speeds. However, the intake valves may close before enough air has entered each combustion chamber, reducing performance. On the other hand, if the camshaft keeps the valves open for longer periods of time, as with a racing cam, problems start to occur at the lower engine speeds. This will cause unburnt fuel to exit the engine since the valves are still open. This leads to lower engine performance and increased emissions. For this reason, pure racing engines which are designed to idle at speeds close to 2,000 rpm, cannot idle well at the lower speeds (around 800 rpm) expected of a road car."
"The next step was taken in 1989 by Honda with the VTEC system. Honda had started production of a system that gives an engine the ability to operate on two completely different cam profiles, eliminating a major compromise in engine design. One profile designed to operate the valves at low engine speeds provides good road manners, low fuel consumption and low emissions output. The second is a high lift, long duration profile and comes into operation at high engine speeds to provide an increase in power output."
From this:
http://en.wikipedia.org/wiki/Variable_valve_timing
Another good read:
http://www.asashop.org/autoinc/jan2005/techtips.htm
"The next step was taken in 1989 by Honda with the VTEC system. Honda had started production of a system that gives an engine the ability to operate on two completely different cam profiles, eliminating a major compromise in engine design. One profile designed to operate the valves at low engine speeds provides good road manners, low fuel consumption and low emissions output. The second is a high lift, long duration profile and comes into operation at high engine speeds to provide an increase in power output."
From this:
http://en.wikipedia.org/wiki/Variable_valve_timing
Another good read:
http://www.asashop.org/autoinc/jan2005/techtips.htm
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