Staying in VTEC after 1st - 2nd shift
12-13-2005, 12:26 PM
#21
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I don't care how fast the shift is made. Even if it's a computer controlled 20ms shift from 1st to 2nd at 8200rpm, the engine will still end up at 5350 rpm. Anybody claiming no loss of VTEC has one of two things happening - either a) the ECU is programmed to stay on the high cam in this situation, but I've never experienced this or heard about it happening to anybody else, or b) the clutch slips enough (either via shift technique or clutch delay valve) that the engine is above 6000 rpm once the clutch is fully engaged.
1st gear at 8200rpm is 38.9 mph. 2nd gear at 38.9 mph is 5350 rpm.
And while the split second spent on the low-speed cam likely doesn't effect acceleration times much, it is very noticeable and annoying IMO.
1st gear at 8200rpm is 38.9 mph. 2nd gear at 38.9 mph is 5350 rpm.
And while the split second spent on the low-speed cam likely doesn't effect acceleration times much, it is very noticeable and annoying IMO.
12-13-2005, 12:30 PM
#22
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Originally Posted by Elistan,Dec 13 2005, 01:26 PM
I don't care how fast the shift is made. Even if it's a computer controlled 20ms shift from 1st to 2nd at 8200rpm, the engine will still end up at 5350 rpm. Anybody claiming no loss of VTEC has one of two things happening - either a) the ECU is programmed to stay on the high cam in this situation, but I've never experienced this or heard about it happening to anybody else, or b) the clutch slips enough (either via shift technique or clutch delay valve) that the engine is above 6000 rpm once the clutch is fully engaged.
1st gear at 8200rpm is 38.9 mph. 2nd gear at 38.9 mph is 5350 rpm.
And while the split second spent on the low-speed cam likely doesn't effect acceleration times much, it is very noticeable and annoying IMO.
1st gear at 8200rpm is 38.9 mph. 2nd gear at 38.9 mph is 5350 rpm.
And while the split second spent on the low-speed cam likely doesn't effect acceleration times much, it is very noticeable and annoying IMO.
12-13-2005, 12:41 PM
#23
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Correct, using the gear calculator I show about that much below 6000rpm for an AP1 1st->2nd shift. My theory is that the clutch slippage is enough to get the revs up past 6000rpm during the shift, since it's such a small interval.
It'd be nice if somebody with a datalogger that has 0.1sec resolution could post a trace... (Does such a device exist? The OBDII scanner I played with has about a 0.5 second scan time which isn't quite fine enough I think?)
It'd be nice if somebody with a datalogger that has 0.1sec resolution could post a trace... (Does such a device exist? The OBDII scanner I played with has about a 0.5 second scan time which isn't quite fine enough I think?)
12-13-2005, 12:47 PM
#24
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Originally Posted by Elistan,Dec 13 2005, 01:41 PM
Correct, using the gear calculator I show about that much below 6000rpm for an AP1 1st->2nd shift. My theory is that the clutch slippage is enough to get the revs up past 6000rpm during the shift, since it's such a small interval.
It'd be nice if somebody with a datalogger that has 0.1sec resolution could post a trace... (Does such a device exist? The OBDII scanner I played with has about a 0.5 second scan time which isn't quite fine enough I think?)
It'd be nice if somebody with a datalogger that has 0.1sec resolution could post a trace... (Does such a device exist? The OBDII scanner I played with has about a 0.5 second scan time which isn't quite fine enough I think?)
12-13-2005, 04:06 PM
#25
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Originally Posted by fshwcrs,Dec 12 2005, 11:36 PM
im thinking about getting a vafc and dropping the engagement point 100rpm
I can't wait to get mine. I'll be tuning it sometime this spring and hoping to gain at least 10 whp.
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