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Message: <blockquote data-quote="buck-7" data-source="post: 344406" data-attributes="member: 5642">hmm lets see, vvt-i was develop to enhance the induction timing by changing the cam phasing from normal to advance and vice versa. with this a normal engine could breath better at both low and high rpm where engines without vvt-i will start to choke.the vvt-i system has always been evolving like the most recent the vvtl-i, which can be seen in the new celica and mrs.this system works almost the same way the honda vtec system. most of the modern cars uses vvt-i or vvtl-i but each manufacturer will have its own name for it. bmw-valvetronik, honda-vtec, daihatsu-dvvt ect.basically the vvt-i is an automated adjustable pully that will optimise the cam setting according to engine speed and load. so you dont have to stop the car and adjust the pulley whenever you want power or just to drive economically.to get the best out of an na or naturally aspirated (all non turbo or supercahrged) engine you have to rev, the higher the rev the more hp you make. revving a 12v engine feels lighter and easier than an 8v engine, this is because the more valves you have the easier the engine to breath. so engineers have calculated without sacrificing strengh and other variables that the most efficient number of valve per-cylinder is five.now for the throttle part its the same case as the valves, the more throttle you have the better the flow.by taking out the vvt-i the 20valve is still technically better than the 16v. this is because the 20v was develop for high revving applications and the 20v cylinderhead was actually develop with the help from yamaha as it is the same with all 4a-g engines. hence why the 20v behave more like a bike engine.in order to develop more power in the 16v, you have to lighten and ballence the internals, slot in high compression pistons, fit a high duration cams (272), fit individual throttle bodies, port and polish the cylinder head, all of which the 20v already have from the factory. infact the 20v is basically a detuned race engine.going back to taking out the vvti system is actually not a good idea. this is because the 20v is designed to have loads of power at high revs, it suffer on the low end output with a high revving cam. that is one of the reason why the vvt-i was included in the development of the engine although.i got more but type later lah, sleepy already.ps: i'm sadly taking out the vvt-i because it have develop a serious problem which actully can be fixed but not in malaysia because nobody have the knowledge and parts to do it. :(</blockquote>

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