G'day biologyboy,Thank you for your question.VTEC stands for Variable valve Timing and lift Electronic Control. It is system developed by Honda to improve the combustion efficiency of its internal combustion engines throughout the RPM range. This was the first system of its kind and eventually led to different types of variable valve timing and lift control systems that were later designed by other manufacturers (VVTL-i from Toyota, VarioCam Plus from Porsche, and so on). It was invented by Honda's chief engine designer Kenichi Nagahiro.In the regular four-stroke automobile engine, the intake and exhaust valves are actuated by lobes on a camshaft. The shape of the lobes determines the timing, lift and duration of each valve. Timing refers to when a valve is opened or closed with respect to the combustion cycle. Lift refers to how much the valve is opened. Duration refers to how long the valve is kept open. Due to the behavior of the gases (air and fuel mixture) before and after combustion, which have physical limitations on their flow, as well as their interaction with the ignition spark, the optimal valve timing, lift and duration settings under low RPM engine operations are very different from those under high RPM. Optimal low RPM valve timing, lift and duration settings would result in insufficient fuel and air at high RPM, thus greatly limiting engine power output. Conversely, optimal high RPM valve timing, lift and duration settings would result in very rough low RPM operation and difficult idling. The ideal engine would have fully variable valve timing, lift and duration, in which the valves would always open at exactly the right point, lift high enough & stay open just the right amount of time for the engine speed in use.In practice, a fully variable valve timing engine is difficult to design and implement. Attempts have been made, using solenoids to control valves instead of the typical springs-and-cams setup, however these designs have not made it into production automobiles as they are very complicated and costly.The opposite approach to variable timing is to produce a camshaft which is better suited to high RPM operation. This approach means that the vehicle will run very poorly at low rpm (where most automobiles spend much of their time) and much better at high RPM. VTEC is the result of an effort to marry high RPM performance with low RPM stability.Additionally, Japan has a tax on engine displacement, requiring Japanese auto manufacturers to make higher-performing engines with lower displacement. In cars such as the Supra and 300ZX, this was accomplished with a turbocharger. In the case of the RX-7, a wankel rotary engine was used. VTEC serves as yet another method to derive very high specific output from lower displacement motors.VTEC makes your engine perform better and gives you greater horsepower per litre. It would be best suited for someone who wants power without paying too much at the petrol pump.I have attached sources for your reference.Regards
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