Honda Car Forum

disadvantages?

vtec controls the engine's valve timing. vtec engines will have a larger hp gain then non vtec engines.vtec does not mean it is more performance tuned. vtec makes the engine cycle more efficient. In the case of the new 2006-2007 non-si honda civic. v-tec engages at low rpms for more efficient gas usage.

The V-Tec engine is more performance tuned than their economical engines... that and there is a million stage-one snap on mods for those engines.Personally, I don't think it really matters... it's kind of a performance thing that wanna-be street racers enjoy boasting about

Honda's VTEC system is a simple method of endowing the engine with multiple camshaft profiles optimized for low and high RPM operations. Instead of one cam lobe actuating each valve, there are two: one optimized for low-RPM stability & fuel efficiency; the other designed to maximize high-RPM power output. Switching between the two cam lobes is controlled by the ECU which takes account of engine oil pressure, engine temperature, vehicle speed, engine speed and throttle position. Using these inputs, the ECU is programmed to switch from the low lift to the high lift cam lobes when the conditions mean that engine output will be improved. At the switch point a solenoid is actuated which allows oil pressure from a spool valve to operate a locking pin which binds the high RPM cam follower to the low rpm ones. From this point on, the poppet valve opens and closes according to the high-lift profile, which opens the valve further and for a longer time. The switch-over point is variable, between a minimum and maximum point, and is determined by engine load; the switch back from high to low rpm cams is set to occur at a lower engine speed than the up-switch, to avoid surging if the engine is asked to operate continuously at or around the switch-over point. The DOHC VTEC system has high and low lift cam lobe profiles on both the intake and exhaust valve camshafts.The VTEC system was originally introduced as a DOHC system in the 1989 Honda Integra and Civic CRX SiR models sold in Japan and Europe, which used a 160 bhp (119 kW) variant of the B16A engine. The US market saw the first VTEC system with the introduction of the 1990 Acura NSX, which used a DOHC VTEC V6 with 270 hp. DOHC VTEC engines soon appeared in other vehicles, such as the 1992 Acura Integra GS-R (B17 1.7 liter engine). And later in the 1994 Honda Prelude VTEC (H22 2.2 liter engine) and Honda Del Sol VTEC (B16 1.6 liter engine).Honda has also continued to develop other varieties and today offers several varieties of VTEC: iVTEC, iVTEC Hybrid and VTEC in the NSX and some Japanese domestic market cars.































en.wikipedia.org

Basically, VTEC is more powerful and gives an extra boost during high RPMS while a non vtec doesnt. VTEC usually has more horsepower then a non vtec conterpart.VTEC is an electronic and mechanical system in some Honda engines that allows the engine to effectively have multiple camshafts. As the engine moves into different rpm ranges, the engine's computer can activate alternate lobes on the camshaft and change the cam's timing. In this way, the engine gets the best features of low-speed and high-speed camshafts in the same engine.

Honda's VTEC system allows the engine to have two cam timing profiles, for different RPM ranges.The low-RPM profile maximizes fuel economy while providing enough torque for the engine to idle smoothly. The normal cam profile would limit high-end power, so above a certain RPM, the engine switches to...The high-RPM profile features increased intake and exhaust valve duration and overlap, giving the engine a higher air flow rate, and thus, more power. A performance cam profile that is good at high RPM will cause the engine to idle poorly.An engine with a single, fixed valve profile (not to be confused with a single overhead cam engine) must be designed as a compromise. It won't idle quite as efficiently, it won't have quite as much low-end torque, and it won't have quite as much top-end power.

(*laughter*) Based on my experience the vtec kicks in and you're going much faster than you intended...unlike with the non-vtec. This is, at least, according to the nice deputy who pulled me over and wrote me a ticket.