VTEC is NOT about Variable Valve Timing - its about valve lift!

[Atlblkz06]

STOP mixing VTEC with VVT!

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.

It's true that the engine's valve timing changes, but that's a secondary to the primary objective of VTEC - which is valve lift.

i-VTEC: (intelligent-VTEC) introduced continuously variable camshaft phasing on the intake cam of DOHC VTEC engines. The technology first appeared on Honda's K-series four cylinder engine family in 2001 (2002 in the U.S.). In the United States, Honda first debuted the technology on the 2003 Honda Civic Si EP3 with the economy version. Valve lift and duration are still limited to distinct low- and high-RPM profiles, but the intake camshaft is now capable of advancing between 25 and 50 degrees (depending upon engine configuration) during operation. Phase changes are implemented by a computer controlled, oil driven adjustable cam gear. Phasing is determined by a combination of engine load and rpm, ranging from fully retarded at idle to somewhat advanced at full throttle and low rpm. The effect is further optimization of torque output, especially at low and midrange RPM.

Finally! You can now have real VVT without a change in active cam profiles !

Toyota's VVT was a 2 mode CAM PHASING system (no lift) and eventually progressed into VVT-i which allowed true variable timing.
Toyota's VVTL-i (Variable Valve Timing and Lift intelligent system) included what the original VTEC had - 2-mode valve lift adjustment.

So there you have it, VTEC IS NOT VVT. Honda calls it Variable Valve Timing because technically the valve timing changes. You cant change valve lift efficiently without changing timing.

[Z0_o6]

I think I love you.



[Hondabuilder]

[RBS]

cool

[5speed]

I already knew this.

[e30pwr]

STOP mixing VTEC with VVT!

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.

[I]It's true that the engine's valve timing changes, but that's a secondary to the primary objective of VTEC - which is valve lift.

wait a minute, VTEC by their definition does change the valve timing? Even if its a secondary function it still performs it correct? excuse the lack of knowledge on the topic.

[5speed]

wait a minute, VTEC by their definition does change the valve timing? Even if its a secondary function it still performs it correct? excuse the lack of knowledge on the topic.

Yes, it is a secondary function. It is only done in order to cause the primary function.

[Atlblkz06]

wait a minute, VTEC by their definition does change the valve timing? Even if its a secondary function it still performs it correct? excuse the lack of knowledge on the topic.

Well, it does not "change" valve timing. It pretty much swaps between two different and discrete cam profiles. Since its a completely different lobe, the timing happens to be different.

Thanks for the support! I'm just sick of people talking about VTEC like its just another system like VANOS (BMW) that simply changes the valve timing while completely ignoring the valve lift part which is what VTEC is about. Here are a few videos to illustrate:

How VTEC Works:
http://www.youtube.com/watch?v=AcT_ZyY3F0k
(http://www.youtube.com/watch?v=AcT_ZyY3F0k)
Toyota's Variable Valve Timing (does not modify valve lift, only timing):
http://www.youtube.com/watch?v=iKo28HMLhK0&feature=related
Another very similar system by Kawasaki:
http://www.youtube.com/watch?v=dSZXepU7Sks&feature=related
(http://www.youtube.com/watch?v=dSZXepU7Sks&feature=related)

One crucial thing to understand is that "Engines with a fixed valve timing can only operate most efficiently and one specific speed". This is why V8 engines with aftermarket "high performance" cams lope at low speeds - they lope because they are tuned for high(er) speeds and are inefficient at idling since they do not employ VVT (First 3 gen Vipers, all Corvettes, Mustangs etc).

To have the ultimate engine that idles well, develops crazy power, and keeps emissions down - it will need ALL of the technologies out there working in sync: Direct Injection, Variable Valve Lift, Variable Valve Timing, and couple it with a pair of small turbos. Or if you're SAAB, you can throw money at Variable Compression as well (good try but..it failed :( )

[speedminded]

Valve Tick Engine Crack

*EDIT*
Throw in BMW's VANOS and Dual VANOS and you'll throw everyone off lol!

[Atlblkz06]

I prefer busting on DSM* Mitsubishi Induced Volatile Eccentric Crankwalk
Thats the best I could come up with. Reps to those who can make up something better :cheers:

*: DSM or Diamond-Star Motors IS to be confused with Mitsubishi corp.

[Kevykev]

So why is i not called VVTaLEC or V-TLEC

















or VLEC?




















:D

[punkr6]

I already knew this.

you are not alone, my friend....

[5speed]

Because Vtec sounds better and it's a Honda.


you are not alone, my friend....

Reps

Edit: I must spread my reps lol

[Theycall_Metue]

most people already know this.
vtec is just easyer to say
v+v+t+l+i v.s v+tec

im not saying i go around telling everybody , example, yeah my toyota celica gts has vtec etc...
to your close buddies vtec is just easier to say instead of v+v+t+l+i etc.....





just stating my point
the end

[egpower904]

I prefer busting on DSM* Mitsubishi Induced Volatile Eccentric Crankwalk
Thats the best I could come up with. Reps to those who can make up something better :cheers:

*: DSM or Diamond-Star Motors IS to be confused with Mitsubishi corp.
i definitely got one.

Mitsubishi's Imitation Vtec Except Crappier.

:D

[Atlblkz06]

i definitely got one.

Mitsubishi's Imitation Vtec Except Crappier.

:D

Nice! :lmfao:

[egpower904]

haha ive been saving that one for the right time.

[egpower904]

haha ive been saving that one for the right time.

thats what she said

[00 blk G20t]

since all the "vtac" talk is going on.....heres a few facts from the nissan NEO VVL wiki.

NEO VVL:This engine was used by Nissan from 1997 to 2001
One difference from Honda's VTEC system is that NEO VVL engages the change of intake and exhaust cams independently for a flatter, more consistent power band. On the SR20VE, the intake camshaft is switched at 5000 rpm, and the exhaust at 6500 rpm. However this trait was not included on the newer '20V' version, as both camshafts engage at the same RPM.
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so nissan had its own version of "i-vtec" before honda did in 2001.

[speedminded]

since all the "vtac" talk is going on.....heres a few facts from the nissan NEO VVL wiki.

NEO VVL:This engine was used by Nissan from 1997 to 2001
One difference from Honda's VTEC system is that NEO VVL engages the change of intake and exhaust cams independently for a flatter, more consistent power band. On the SR20VE, the intake camshaft is switched at 5000 rpm, and the exhaust at 6500 rpm. However this trait was not included on the newer '20V' version, as both camshafts engage at the same RPM.
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so nissan had its own version of "i-vtec" before honda did in 2001.Why don't you try stepping it back even further to 1987 when Nissan introduced the N-VCT aka N-VCS ;)

http://en.wikipedia.org/wiki/N-VCT