Vtec works on Rpm's and Oil pressure and a few other factor wich I cant remeber now. But I dont think its good to lower ur crossover point at all because all the oil pressure has not built up yet for the actuall vtec to engage properly.
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Vtec works on Rpm's and Oil pressure and a few other factor wich I cant remeber now. But I dont think its good to lower ur crossover point at all because all the oil pressure has not built up yet for the actuall vtec to engage properly.
As an answer to the original thread creators question, chnaging the vtec engagement alone, with no other tuning will have absoultly no effect what-so-ever on a cars "Top Speed" and "Max Power".
For instance if a car makes say 150Hp @ 7000 Rpm with 5500 Rpm VTEC crossover, if you change the VTEC engagment to say 3000 rpm, by the time it reaches 7000 rpm it will still be making 150Hp.
VTEC controlloer also has nothing to do with your gear ratios, final drive, or engine Rev Limit thus I can't see how it would affect your top speed.
-KB
For a stock unmodified car, the VTEC switchover point is optimum. If you alter your car by changing I/H/E, ECU or remapping the fuel maps, then the optimum point for VTEC switchover has changed. Only then will a VTEC controller be useful.
Oil pressure is maintained by the oil pump. Once your engine is warmed up, the oil pump will maintain oil pressure throughout the rev range. So you can engage the VTEC system at any point in the rev range. Of course, if you set your VTEC point too low, and your hi-lift cams are very aggressive, it means you are lugging your engine since not enough torque is preduced to increase the revs. Imagine doing this at WOT, not too healthy for your engine.