VTEC Vs. I-VTEC (The Definitive Duel)?

[Honda Enthusiast]

Dear friends,

My Dad recently purchased a 2006 Honda CRV Sports with a powerful I-VTEC engine inside...we've gone on a few family cruises and I've noticed how different the I-VTEC engine is to my 3.0 Litre V-6 VTEC engine and that of my friend's 4 Cyclinder Prelude's VTEC engine.

First of all, have to let you know that I do not know much about engines let alone the technicalities of VTEC...however, the following are what I've noticed first hand between the two and hope people can discuss this topic futher so we all can learn...

OK, now, VTEC is obviously a engine that is very dynamic because it has Variable Timed Piston-shifting technology to maximise Torque and power...with my modded Accoord, upon changing gears from 2-3 - one can actually feel it kick it...literally VTEC kicks in and gives you like 1 second of VTEC blast...feels and flies great!! However, with the I-VTEC engines like that of my friends Honda EURO and my Dad's CRV...this kick-in doesn't happen and you hardly notice the gear change, especially on an automatic.

I've met a few friends, and they all claim that with the new I-VTEC engines, because it's designed to make the ride more smoother and the change of gears less aggressive; has toned down on it's VTEC power...hence, many believe the old VTEC engines that are in the 4,5 and 6th Generation Accords are by far-more dynamic, powerful and capable of reaching highspeeds faster and more aggressively...well, the above are just my personal opinions...hope to hear everyone else's reply!

Thanks all!!

Sky Nguyen

[EuroDude]

The CRV i-VTEC is missing VTEC on the exhaust CAM, so its not as powerful as the Euro's. But both have VTC so Variable timing is always active, which means that the VTEC "kick-in" is not as prodominant (and doesnt really need to be) as like the classic VTEC engines.
So instead of all the power kicking at a certain RPM, i-VTEC smooths out the VTEC power delivery over the whole RPM range and is less noticable, despite being considerably more torquey especially at low RPM.


So basically the practical difference being~

VTEC = Need to rev high to get decent power, not good for traffic and engine longetivety.
i-VTEC = Decent power delivery over the whole RPM range, useful for traffic. Whilst providing VTEC y0 up high when needed.

[Honda Enthusiast]

The CRV i-VTEC is missing VTEC on the exhaust CAM, so its not as powerful as the Euro's. But both have VTC so Variable timing is always active, which means that the VTEC "kick-in" is not as prodiminant as the classic VTEC engines.
So instead of all the power kicking at a certain RPM, i-VTEC smooths out the VTEC power delivery over the whole RPM range and is less noticable, despite being considerably more torquey especially at low RPM.


Arrh....I see.... like I said, I am no engine expert by far...but from a pratical point of view... that kick in...damn, I like the classic engines better... apparently, the engineers at honda created I-VTEC to smooth out transmission and gear changes...however, I kinda like the classic ones better as you can actually and physically feel the "kick in"...damn, Honda's are groice...all other vehicles do not have this 'kick in" effect... Holden's Alloytech engines, although quite powerful, does not have this technology!

Would it be fair to say the aggressive power in the old engines are missed by some??

Sky

[CUL8R]

you gotta take a seat in a properly tuned honda mate, power is not about how it feels its being able to linearly transfer it to the ground. and well tuned NA honda should have minimal "kick" so to speak. honda detuned some of their cars (prelude for example) to have a violent high cam crossover so to lure people into thinking it is quicker than it really is.

[EuroDude]

The i-VTEC engines still have the kick in, but Honda decided to make it kick in at very high RPM - mainly because it wont make any significant power improvement if VTEC kicked in earier.

But if you change the VTEC CAM to a more aggressive profile and lower the VTEC engagement RPM, then you have the best of both worlds. Torquey performance over the whole RPM range, plus that classic VTEC kick-in. The JDM Euro-R's 2.0L iVTEC engine is tuned this way. Our 2.4L iVTEC's are more conservative.

[Honda Enthusiast]

The i-VTEC engines still have the kick in, but Honda decided to make it kick in at very high RPM - mainly because it wont make any significant power improvement if VTEC kicked in earier.

But if you change the VTEC CAM to a more aggressive profile and lower the VTEC engagement RPM, then you have the best of both worlds. Torquey performance over the whole RPM range, plus that classic VTEC kick-in. The JDM Euro-R's 2.0L iVTEC engine is tuned this way. Our 2.4L iVTEC's are more conservative.


That makes sense and sound logical... I've heard your explaination a few times from friends... that's right, the new I-VTEC engines 'kick-in' on higher RPMS... something like 6k's whereas with the older Accords, I can start to feel VTEC 'kicking in' ar around 4-5k RPM's!

Without getting Turbo, is there a way I can fine tune my engine to make it more powerful?

[EuroDude]

Yes you can install more aggresive CAM(s) and Intake/exhaust system, and a retuned ECU to get the most out of the engine.

[Chris_F]

have a read - i'm not sure that you understand what i-vtec is exactly, and it takes time to explain.

thurough explanation
http://www.k20a.org/forum/showthread.php?t=74&highlight=i-vtec

[Honda Enthusiast]

have a read - i'm not sure that you understand what i-vtec is exactly, and it takes time to explain.

thurough explanation
http://www.k20a.org/forum/showthread.php?t=74&highlight=i-vtec

Cheers mate...but the link doesn't work as you have to signup! Can you paste a extra or something in here?

[EuroDude]

There's a wiki: http://en.wikipedia.org/wiki/VTEC

VTEC adds aggressive CAM profile lobes (or an economy profile).
VTC adds variable CAM timing in the CAM gear.

[Honda Enthusiast]

There's a wiki: http://en.wikipedia.org/wiki/VTEC

VTEC adds aggressive CAM profile lobes (or an economy profile).
VTC adds variable CAM timing in the CAM gear.


Cool, thanks for that! Very informative!

So personally, do you think VTEC or IVTEC is better?

[EuroDude]

Well because i-VTEC is the latest honda engine tech and basically a VTEC engine with the addition of VTC, i-VTEC is most beneficial generally.

Although at the moment there are only a few i-VTEC engines, so it depends on the application

[aaronng]

Read this too: http://ozhonda.com/forum/showpost.php?p=748047&postcount=12

I wrote it.

[Honda Enthusiast]

Read this too: http://ozhonda.com/forum/showpost.php?p=748047&postcount=12

I wrote it.


Thanks mate!

[Honda Enthusiast]

VTEC Yo'all!!

[EuroDude]

VTEC Yo'all!!

Spam belongs in the Spam thread (http://www.ozhonda.com/forum/showthread.php?t=49128) y0!

[WhiteAP1]

And this thread belongs in the lounge

[Honda Enthusiast]

How come different cars have different VTEC kick-in RPM ranges?

[EuroDude]

Its the optimal RPM for VTEC, all model engines are different in terms of:

Sports vs economy
Displacement (engine size)
DOHC vs SOHC
Intake and exhaust differences
Gearbox ratio's

[SHIFTY]

Sorry 2 'blow-in' but i got SOHC VTEC-E and i would like 2 know if i can remove the "pins" so both valves are constantly open (so it is performance rather then econamy) thanx.... hope u understand this thought came from reading this:

"SOHC VTEC-E
Honda's next version of VTEC, VTEC-E, was used in a slightly different way; instead of optimising performance at high RPMs, it was used to increase efficiency at low RPMs. At low RPMs, one of the two intake valves is only allowed to open a very small amount, increasing the fuel/air atomization in the cylinder and thus allowing a leaner mixture to be used. As the engine's speed increases, both valves are needed to supply sufficient mixture. A sliding pin, which is pressured by oil, as in the regular VTEC, is used to connect both valves together and allows the full opening of the second valve."

[Honda Enthusiast]

Guys, I came across this article quite an interesting read for those interested.

http://auto.howstuffworks.com/question229.htm