ok...i am new to honda and starting to learn different aspects of honda engines but have come to a very confusing road.....what is vtec?????how is it different from reg engine....and also what the heck is vtec..please help

 

hey whats up LH. well i'm going to keep this simple. I actually just finished a long thread about vtec at purehonda.com. its in the accord forum under the thread "not feeling vtec"

basically inside your engine you have a cam shaft. this camshaft rotates above the cylinders and opens and closes the valves. the valves are what let air in and air out. so this cam shaft is opening the intake valve to let air in, then closes the intake valve and the spark plug ignites the fuel and air mixture, pushing the piston down. so at this point we have the leftover hot gases still in the cylinder so as this cam shaft is still rotating it opens the exhaust valve that lets all of this exhaust gases out. these gases flow into your headers then down into your exhaust piping. back to cam shaft. this cam shaft has what we call "lobes". for a visual representation think of a pencil. this pencil is the cam shaft and it's just rotating around and around. on this pencil are "bumps". These bumps, depending on how big the bump is determines how long the intake/exhaust valve stays open. On a SOHC (single overhead cam) there will be two bumps per cylinder (could be more but keeping it simple). one bump as it rotates around opens up the exhaust valve and the other bump opens the intake valve. now if you put a larger bump, which is actually a lobe, it will make these valves stay open longer. staying open longer means the ability to put more air into the cylinder, which with more fuel can create a more combustable explosion. so why not have larger lobes for more air in and out? well it will hurt low rpm performance. if you have small lobes which will help low rpm performance then high rpm performance will suffer. so what honda did is made two sets of lobes for each valve. at low rpm the engine is using the smaller lobes, then at a certain time (depending on circumstances, vtec doesnt actually kick in at a certain rpm) the computer decides to engage the larger lobes for high rpm performance. honda called this system vtec.

all vtec is, is two sets of lobes on a camshaft. what makes it unique is honda really got this system to work very well. they were not the first to do it, but they were the most successful.

go to http://www.howstuffworks.com and look under camshaft. you'll love it. look at how the engine works also. i love that site.