can any one explain the difference between vtec and i-vtec engine? i heard i-vtec isn't as good as vtec engine. why?

 

what's vtec?

 

I'll keep things simple. Honda's preschool definition/formula of i-VTEC is this: VTEC + VTC = i-VTEC.

The major difference of VTC (variable timing control) is that instead of having just one point of engagement (at a specified RPM) on the intake and exhaust cams like the traditional VTEC has, i-VTEC uses VTC to make the intake cam constantly variable. It allows more seamless acceleration and a smoother torque curve, which normally aspirated 4-cylinder engines aren't traditionally known for.

Utilizing i-VTEC in the K-series engines has great advantages over the traditional VTEC engines of the 1990s. More flexible powerbands, smoother transitions on and off the "high cam" profile, and increased economy are just a few of the points of advantage. They also have more power potential when it comes to available power and torque without the use of forced induction.

Do we need to go further into detail? I can if we need to, but then we have to get pretty technical (and long-winded).

 

answering my own question

care of www.howstuffworks.com....

If you have read How Car Engines Work, you know about the valves that let air into the engine and let exhaust out of the engine. You also know about the camshaft that controls the valves. The camshaft uses rotating lobes that push against the valves to open and close them. This animation from How Camshafts Work can help you understand how the camshaft opens and closes the valves:






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. Several of the links below go into the actual mechanics of the VTEC system if you are interested. Several engine manufacturers are experimenting with systems that would allow infinite variability in valve timing. 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...

 

Bottom line, Ivtec is better.
It's got regular Vtec in it plus variable valve timing.

 

I miss those old VTEC screams from DC2s and S2Ks.

 

This is the only downside I've heard of with i-VTEC and even the newer VTEC applications. Many of us liked the old "kick in the pants" transition. But Honda knows what they are doing. Every year their engines seem to be more powerful yet more efficient at the same time.

Slats

 

I have a VTEC and I love the kick and sound I hear at 5.5k rpm.... WOW!!! LOVE IT!!!! I'm gonna be sad when I own an I-vtec one day....but its too be expected.

 

Even though that kick in the pants is great...the i is better because its basically gives you v-tec plus a stronger power brand throughout. I'm sure you've realized the extremely low amounts of power in honda engines in low rpms, i-vtec takes some of that big boost a distributes it so we have more power throught out the range.

Vtec is like eating fast food for lunch and steak for dinner

I-vtec is like eating homemade raviolis all day long

(insert food preferences as you see fit)

 

I have driven dc5 Ivtec, and the Ivtec kick is quick apparent, nothing smooth.
Mine EuroR, is a little smoother, but still a difinete change in kick,noise and power.

 

hmmm ..... i-VTEC is like...getting a date with a hottie that's waaay outta your leage!

Slats

 

 

Yeah... I too somewhat miss the VTEC kick from the H22A1 on my 5th gen Prelude.

Though with the iVTEC on the TSX, I can still feel a kick (less abrupt) at 6000rpm, only complaint is that there're only a bit more than 1000rpm to the redline. Boy, does it scream to the redline very quickly (not a bad thing of course). So I can't wait to get Hondata on mine, so the kick takes place at 5000rpm instead

 

i vtec is more intellgent

 

So if we called you i-dzuy, would we get less trout slappage?

 

Not necessarily, you just would notice it less. You'd have infinitely variable troutslaps.

 

:troutslap