Yes, I did a search on this, and I found plenty of topics on 'VTecs' but my question is... What does it do, as opposed to a regular Honda engine. Yes, I have a VTec, and I know what it stands for (Valve Timing Electronic Control), I know a lot about Civics, but this has been buggin' me.

Another thing, I have the d16z6 motor, I believe its abotut 125 HP, my brother has a 91 Teggy GS, its a DOHC Honda motor, I think its about 135 HP, obviouly my car weighs about 500-600 lbs less. I've never raced my bro, but would the VTec help me that much?

 

bump

 

Vtec makes you go fast yo. Seriously, I have a pretty good idea what it does but I know someone on here has a more technical description that I do. The basic theory is that when vtec engages you're intake valves open more and the car dumps more fuel in. I believe on a b-series the exhaust side also opens more in vtec. I'm sure there is a lot more to it but that is the basics.

 

search is your friend..........
that being said,


It turns out that there is significant relationship between the way the lobes are ground on the camshaft and the way the engine performs in different rpm (rotations per minute) ranges. To understand why this is the case, imagine that we are running an engine extremely slowly -- at just 10 or 20 rpm, so it takes the piston seconds to complete a cycle. It would be impossible to actually run a normal engine this slowly, but imagine that we could. We would want to grind the camshaft so that, just as the piston starts moving downward in the intake stroke, the intake valve would open. The intake valve would close right as the piston bottoms out. Then the exhaust valve would open right as the piston bottoms out at the end of the combustion stroke and would close as the piston completes the exhaust stroke. That would work great for the engine as long as it ran at this very slow speed.

When you increase the rpm, however, this configuration for the camshaft does not work well. If the engine is running at 4,000 rpm, the valves are opening and closing 2,000 times every minute, or thirty to fourty times every second. When the intake valve opens right at the top of the intake stroke, it turns out that the piston has a lot of trouble getting the air moving into the cylinder in the short time available (a fraction of a second). Therefore, at higher rpm ranges you want the intake valve to open prior to the intake stroke -- actually back in the exhaust stroke -- so that by the time the piston starts moving downward in the intake stroke, the valve is open and air moves freely into the cylinder during the entire intake stroke. This is something of a simplification, but you get the idea. For maximum engine performance at low engine speeds, the valves need to open and close differently than they do at higher engine speeds. If you put in a good low-speed camshaft, it hurts the engine's performance at high speeds, and if you put in a good high-speed camshaft it hurts the engine's performance at low speeds (and in extreme cases can make it very hard to start the engine!).

VTEC (which stands for Variable Valve Timing and Lift Electronic Control) 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.

For example, imagine that each valve had a solenoid on it that could open and close the valve under computer control rather than relying on a camshaft. With this type of system, you would get maximum engine performance at every rpm range. Something to look forward to in the future...

(howstuffworks.com)

 

when u reach a certain speed more valves open engine roars and u get alot more fuel.
car pulls harder and accelerates quicker
overall like nitrous effect but not as dramatic and alot safer

 

Alright, here is a not that complicated answer.

Basicly, in your engine, you have the cam which i'm assuming you know what that is. The cam has the different height ridges on it. There are usually a cluster of smaller height ovals on the cam and larger height ovals on the cam gear. When all the conditions are right, (I think the engine hase to be a certain temp, certain rpm, and some other stuff), then the engine switches over to VTEC mode. When this happens, oil pulses into the "vtec channel" (i know thats not the official name) and pushed these pins over which connects all the cam lobes together so now instead of the intake and exhaust valves being opened by the smaller cam height, they all open by being pushed by the higher cam height, which basicly pushes the valves open more so more air flows in and out. This is what happens. Some of my names are probably off but the concept I think is there. Anybody else can correct that.

So all in all, while use sohc d16y7 people are in high rpms with low rpm flow, you lucky vtec people get to use an extra cam lobe to get some higher valve lift, you lucky bastards....

All in all, I have a d16y7 and vtec kicks my all... enough said...

 

Wow, very good. Thanks a lot man.

 

dammit, I was the only person posting when I saw this and now, there are three ahead of me, oh well, at least you know now.

 

really not worth it to bump this topic!!!

 

this is where i learned. http://auto.howstuffworks.com/question229.htm

 

in relation to this topic when does vtec actually kick in, on my stock D16Y8 it seems like it kicks in at about 5700 revs. am i wrong or what cuz that's when i hear the sound difference in the engine bay

 

VTEC for n00bs ----> http://www.teamdelsol.com/tech...c.htm