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VTEC crossover point

Practical Reflash Tuning

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This question is in relation to the K series tuning you did on the endurance Integra.

Would it be correct to assume that Honda set the Vtec changeover point at 5600rpm more for emissions and low down driveability rather than out right power? 4500rpm is quite a large change when you only have an aftermarket exhaust fitted. The dyno graph speaks for itself for why 4500 is optimal but just wondering what Honda had in mind when setting it from factory. How much is the optimal crossover point likely to change when extensive engine mods are carried out?

It's possible that the changeover was set for subjective reasons; i.e., they felt their target customer liked the VTEC's kicking in Yo feel on a test drive.

I believe it was for emissions as essentially the car only operates on low cam for the drive cycle emissions test. This was however third hand information so I can't say how accurate it is. In particular with the K20 engine there is significant midrange to be gained in adjusting the VTEC changeover point on an otherwise 100% stock engine.