what's VTEC?

[urasula]

hey all honda owners! what's is VTEC? i read some where that it stands for something like variable timing electric lift or something, but what does all that mean? can someone explain it to me?

i'm not a honda owner but i still like to understand that VTEC is cuz everyone is oh..VTEC this VTEC that, and i wonder how many really understand the mechanics behind it besides just what it stands for.

[DVSNCYNIKL]

All VTEC is, is a higher lobe cam in the engine. When you hit the gas really hard, and the rpm's are reaching the upper range, the car get's like a sudden burst of acceleration or power. Most people like it because of the sound it makes especially if you have a CAI installed. But if you know what variable valve timing is, that is VTEC.

[texan]

To add to/clarify what DVS said, variable valve timing is any system which can vary either cam phasing (retarding or advancing the cam timing), lift or duration of the valve events while the engine is running. Most current systems on the market vary only cam phasing, such as BMW's Vanos system or Toyota's VVTi setup (which are basically eletronically controlled cam gears changing cam phasing throughout the RPM range). In contrast, VTEC actuates a 3rd lobe on the camshaft for each set of intake and/or exhaust valves, which actually changes the profile of the valve events. Both lift and duration can be varied, but cam phasing is not available.

In the newest and very best systems, such as Honda's i-VTEC or Toyota's VVTL-i, you get both cam phasing control and alternate cam lobes. The goal of all these systems is to of course maximize engine power and/or fuel economy (and possibly emmisions), the differences are as follows...

-cam phasing systems are not as ultimately powerful as actually having a seperate, optimized set of cam lobes for low and high RPM (because valve lift and duration are not changeable). They are however "infinitely variable", which means they work throughout the RPM range to smoothly increase power, fuel economy and minimize emmisions.

-variable lift/duration systems are usually two stage setups, meaning two cam lobe profiles for two large RPM ranges. This works pretty damn well as far as maximum power output is concerned, but generally has a noticeable step to the power curve as the big lobes engage. Anyone who has been in a Prelude VTEC, S2000 or Type R is well aware of this abrupt jump in power.

-combining both technologies is currently the furthest anyone has gone in valve actuation technology on production cars, and is the best of both worlds. Power output is maximized from a particular engine over an incredibly large RPM range, which is why Honda and Toyota have both moved to such setups in their newest, highest performance compact car motors. The abrupt jump in power can be minimzed if not completely removed from such systems.


Hope this helps explain things, peace.

[F20C]

Hey Texan is that you? I am 9000RPM from Superhonda.

[texan]

Hey, sup man!! How'd you find this place, through SCC? I've been here for months. If only we could get the whole of SHO over here instead of on that unreliable board (plus Igor, the webmaster here is ULTRA cool and always involved), this place would be the only board I would visit.

[F20C]

Moppie a member I got to know a bit from SHO told me about this forum. Anyways this board is quite nice. But there isn't a lot of dicussion going on. I see forums with threads that date back to May. They need more people on it. Do you know what is going on with SHO?

[texan]

Yeah I know Moppie well, I directed him here awhile back to look at some articles I have written for this site. And no I don't know what's up with SHO, it's the same old BS prolly. We'll be lucky if the board comes back with any posts still on it.

[urasula]

texan,

okay, VTEC = cam phasing. however, cam phasing doesn't automatically adjusts the valve overlap when the engine is in high and low RPMs, right? u said they're "infinitely variable" which works throughout the rpm range. doesn't other cars without vtec work throughout the rpm range? can u explain "infinitely variable" in greater detail cuz i don't really understand it.

i understand that these small and compact engines r designed to produce more power at a higher rpm where more valve overlap is needed. now, i can understand how variable lift/duration systems will help produce more power, but i'll still don't understand how vtec helps.

[F20C]

A lot of them are here. http://clubs.yahoo.com/clubs/shooverflow

[Jay!]

I think you two would make quite persuasive recruiters.

BTW, "VTEC" is the sticker you go pay $28 for when you had to buy a Civic DX. LOL! :hehehe:

[F20C]

I wish Mike had given all the moderator a warning of what he was going to do with the board. We got a whole lot of users asking and we can't give a damn answer.

[Moppie]

Originally posted by Silver S2000
I think you two would make quite persuasive recruiters.

A good idea. Email guys from SHO that you know, and get them here.

And its good to see you here 9000RPM, or F20C, or what ever.
Id always heard bad things about SHO and its poor managment.
But its deffinitly not a problem here. Igor is heavily involved in the site, it really does make a big diffrence. I get the impression hes doing it for the love of it, as well as for any possible financial reward.

[F20C]

Hi Moppie you brought me here remember :sun:. Haven't seen you on SHO in a long time so what's up?

[Moppie]

Originally posted by F20C
Haven't seen you on SHO in a long time so what's up?

Lack of time mostly. I tried there a few times and it was down. But i didnt poke my head in here for a while either. Now PH is down, (similar probs to SHO I think (igor be warned nothing is easy) with bandwidth constraints, and a owner unprepared to tell anyone anything about it).
So im here for bit more. Ill always come here though, its pretty damn cool site, just needs a few more ppl to fill up some more of the Forums.

[Dezoris]

It is a nice outlet