intelligent-VALVE TIMING AND LIFT ELECTRONIC CONTROL ( i-vtec ) Seminar Report Download 


The most important challenge facing car manufacturers today is to offer vehicles that deliver excellent fuel efficiency and superb performance while maintaining cleaner emissions and driving comfort. This paper deals with i-VTEC (intelligent-Variable valve Timing and lift Electronic Control) engine technology which is one of the advanced technology in the IC engine. i-VTEC is the new trend in Honda‘s latest large capacity four cylinder petrol engine family. The name is derived from ‗intelligent‘ combustion control technologies that match outstanding fuel economy, cleaner emissions and reduced weight with high output and greatly improved torque characteristics in all speed range. The design cleverly combines the highly renowned VTEC system – which varies the timing and amount of lift of the valves – with Variable Timing Control. VTC is able to advance and retard inlet valve opening by altering the phasing of the inlet camshaft to best match the engine load at any given moment. The two systems work in concern under the close control of the engine management system delivering improved cylinder charging and combustion efficiency, reduced intake resistance, and improved exhaust gas recirculation among the benefits. i-VTEC technology offers tremendous flexibility since it is able to fully maximize engine potential over its complete range of operation. In short Honda’s i-VTEC technology gives us the best in vehicle performance.


An internal combustion is defined “as an engine in which the chemical energy of the fuel is released inside the engine and used directly for mechanical work”. The internal combustion engine was first conceived and developed in the late 1800‘s. The man who is considered the inventor of the modern IC engine and the founder of the industry is Nikolaus Otto (1832-1891).

Over a century has elapsed since the discovery of IC engines. Excluding a few development of rotary combustion engine the IC engines has still retained its basic anatomy. As our knowledge of engine processes has increased, these engines have continued to develop on a scientific basis. The present day engines have advances to satisfy the strict environmental constraints and fuel economy standards in addition to meeting in competitiveness of the world market. With the availability of sophisticated computer and electronic, instrumentation have added new refinement to the engine design.
From the past few decades, automobile industry has implemented many advance technologies to improve the efficiency and fuel economy of the vehicle and i-VTEC engine introduced by Honda in its 2002 Acura RSX Type S is one of such recent trend in automobile industry.


The latest and most sophisticated VTEC development is i-VTEC (“intelligent” VTEC), which combines features of all the various previous VTEC systems for even greater power band width and cleaner emissions. With the latest i-VTEC setup, at low rpm the timing of the intake valves is now staggered and their lift is asymmetric, which creates a swirl effect within the combustion chambers. At high rpm, the VTEC transitions as previously into a high-lift, long-duration cam profile.
The i-VTEC system utilizes Honda’s proprietary VTEC system and adds VTC (Variable Timing Control), which allows for dynamic/continuous intake valve timing and overlap control.
The demanding aspects of fuel economy, ample torque, and clean emissions can all be controlled and provided at a higher level with VTEC (intake valve timing and lift control) and VTC (valve overlap control) combined.

The i stands for intelligent: i-VTEC is intelligent-VTEC. Honda introduced many new innovations in i-VTEC, but the most significant one is the addition of a variable valve opening overlap mechanism to the VTEC system. Named VTC for Variable Timing Control, the current (initial) implementation is on the intake camshaft and allows the valve opening overlap between the intake and exhaust valves to be continuously varied during engine operation.


i-vtec Diagram
i-vtec Diagram


VTEC (standing for Variable valve Timing and lift Electronic Control) does Honda Motor Co., Ltd. develop a system. The principle of the VTEC system is to optimize the amount of air-fuel charge entering, and the amount of exhaust gas leaving, the cylinders over the complete range of engine speed to provide good top-end output together with low and mid-range flexibility.
VTEC system is a simple and fairly elegant method of endowing the engine with multiple camshaft profiles optimized for low and high RPM operations. Instead of only one cam lobe actuating each valve, there are two – one optimized for low RPM smoothness and one to maximize high RPM power output. Switching between the two cam lobes is controlled by the engine’s management computer. As the engine speed is increased, more air/fuel mixture needs to be “inhaled” and “exhaled” by the engine. Thus to sustain high engine speeds, the intake and exhaust valves needs to open nice and wide. As engine RPM increases, a locking pin is pushed by oil pressure to bind the high RPM cam follower for operation. From this point on, the valve opens and closes according to the high-speed profile, which opens the valve further and for a longer time.

The basic mechanism used by the VTEC technology is a simple hydraulically actuated pin. This pin is hydraulically pushed horizontally to link up adjacent rocker arms. A spring mechanism is used to return the pin back to its original position.
To start on the basic principle, examine the simple diagram below. It comprises a camshaft with two cam-lobes side-by-side. These lobes drive two side-by-side valve rocker arms.

1) Better Fuel Efficiency.
2) High initial torque and relevant high power.
3) Lower emission.
4) Strong performance.


1) Cost is high.
2) Available in Honda Models only.

Currently i-VTEC technology is available In Honda products;
1) Honda CRV
2) Honda CITY
3) Honda Civic
4) Honda Amaze
5) Honda Mobilio
6) Honda Accord

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intelligent-VALVE TIMING AND LIFT ELECTRONIC CONTROL ( i-vtec ) Seminar Report Download 

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