What exactly is VTEC?

Got a '93 Intregra with this same (I guess?) system and was wondering what exactly it is..in psuedo gearhead terminology.... I know on the Acura, the motor "kicks in" around 5600 rpm and a similar deal happens on the VFR at around 7K rpms.


gracias!

 

(Heavy sigh.......) Here we go again. LOL!

The engineering behind the VTEC system is fairly complicated,but basically it's just a fancy way of saying the ECU is switching the engine from "two valve" to "four valve" mode.

Here's an edited reprint of an old post of mine which explains what the VTEC system is and how it works on the VFR800 Dodge,enjoy.

 

Well, Mr. Dodge,


congrats on the new car! Acuras are a good one methinks

However, I believe that the Vtech installed on these motorbikes is not very similar to the one in your car. I THINK that the cars driven with Vtech have "variable valve timing". Other Japanese car companies have come up with their own version of this, I believe my Nissan is dubbed "constantly controlled valve blah blah blah":frown:

The system actually leaves the intake valves open longer in order to get more air in the cylinder before the BANG.

In the VFR motorcycle, it is called Vtech, but it is a little different. The valves are all timed the same. At a certain RPM, however, an extra set of intake valves activates and gives the engine more GUSTO. There is no manipulation of the timing of the valves (no "variable" valve timing), but an extra SET of valves is activated.

Hope this muddles everything up for you LOL:chaingun:

here's to your new Acura:cheersaf:

 

FIXT.

Sorry for waggin' the finger at'cha MTB. :nono:

No offense intended my friend,you were ooooooh so close though.

 

My kid has a computer that has VTECh in it

 

Good summary Stosh-thanks. Did do the google thing and the Wiki page has quite a bit of info on it. Does appear that the VTEC systems do different things cars vs. the bikes.

 

Well fer da cripes sakers don't leave us hangin' here Crusty. :hangme:

Does it switch from two valve to four valve mode at 6400 or 6800 RPM? :lol:

 

What's a valve?

Don't feel bad about not knowing Dodge. I had no idea mine had these when I bought it in 06. Dodn't know until I opened the bich up a couple weeks later and shit my pants when I heard the roar. And I still didn't know what it was. For that matter, other than what I have read here, I had very little idea what it was until I read this thread. And frankly don't give a shit either. All I know is I like what it does. I will leave the techy stuff up to those who are far moretalented in these things than I. Just ride...and ride a lot and ride safe.

 

it goes into dual drive at 3Gbz and man to hear the roar of the disk drive turning...its quite impressive

 

So the exhaust valves are effected as well as the intakes??? IE, you go from an 8 valve motor to a true 4 valve/cyl (16V) motor when this system kicks in? Still breaking this motor in, but on one occassion it hit 7K and jumped sorta...

 

Yes! :nod:

Correctomundo Dodge,you've got it! :whoo: :bravo::high5:arty2:

That is exactly how the VTEC system works on the 6th gen. VFR800 engine.

 

OK...next question...can the ECM be programmed to allow the VTEC to activate at a different rpm?
I keep hearing about this PCIII thing.
Spent lots of time remapping (using a pair of wide-band 02 sensors) the fuel/ignition tables on my Buell using a free piece of software (ECMSpy) to log data, and Megalogviewer software to create the new maps. Ecmspy allows you to view all the engine data in real time and also allows you to disable the 02 sensor (I run the Buell in open loop), reset TPS and a whole bunch of other stuff-a very cool program to say the least. You can even access the ecm remotely using a bluetooth module to connect to your pc. But, back to VFRs...

thanks again for the VTEC info... Still thinking this bike should get better MPG figures in cruising mode if there was a way to adjust A/F values and ignition settings.

Will this PCIII unit allow you to do this..does it have to remain on the bike?

 

I love it when the "2nd set" of valves gets into it.. it reminds me of the power band on the old dirt bikes...only a teeny bit faster :crazy:

 

Is the mileage on these really that bad if you don't keep opening up the second set of valves though? I really have nothing to compare to other than my big assed fucking truck.

 

Vtec: something else to go wrong

If it adds power when the second set of valves kick in then it would be nice to have extra at lower rpm.

Sounds like it is something to do with emission control.

 

Man why dis me tinker, I think you should read the rules in the forum. You do not know what I know and I do not know what you know.

I point out that a lot of others said that when the 4 valves kick in they can feel it. My bike has no hump in the powerband it starts about 4000 and builds smoothly. From what I have gathered the early bikes are not particularly slower than the vtec ones. I have not ridden one although I had a Vmax about 20 years ago and it was a hoot, didn't have vtec although it had a flapper valve between the banks of carbs, I doubt if it needed it.

Vtec probably is for low emissions. Not that there is anything wrong with low emissions.