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wynode
22-08-2003, 10:07 AM
The following information is only a summary and is as accurate as possible. For a detailed description, please follow the links

What is it?
VTEC is an acronym for Valve Timing and lift Electronic Control, and was first implemented by Honda in the late 1980s in the Japanese Domestic Market (JDM) Hondas.
VTEC allows an engine to have multiple cam profiles depending on engine RPM. That is, it provides a smooth idle at low RPM while having the ability to run the equivalent of a 'lumpy' cam at high RPMs.

How does it work?
When the engine reaches high RPM (usually around 6,000+rpm) a small oil filled solenoid gets activated (VTEC solenoid) and this engages a larger cam which pushes down on the valves causing them to lift higher off their seats. This increase in valve lift allows more air to enter the combustion chamber and this combined with more fuel via the injectors allows the engine to make more power.
At low RPM's however this is not feasible because high valve lift results in a rough idle and for everyday driving this is not desireable. Hence VTEC allows a smooth idle at low RPMs while allowing F1 style high lift at higher RPMs.

Here is as good article covering VTEC in more detail:

http://www.leecao.com/honda/vtec/whatsvtec.html

Has it got better?
Over time Honda have implemented a few variations of the VTEC system and have managed to achieve some great results. The most common VTEC system is the DOHC (Double Overhead Cam) system where each set of valves (Intake and Exhaust) has its own cam. DOHC VTEC configuration is optimised for high power output, and is capable of making upto 88kW per litre (as found in the current S2000).
The second impementation of VTEC is that of SOHC VTEC where both sets of intake and exhaust valves are run via a single cam. This mechanism is not for performance but for economy, while still making good power for practical everyday use. With SOHC VTEC, only the intake valves benefit from higher lift and not the exhaust valves.
The latest impementation of VTEC is that of i-VTEC where the system allows continuasly variable valve timing over the rev range which allows for upto 6kW more at peak power with improved torque and fuel efficiency.

Where is it found?
SOHC VTEC is primarily found in the early model Honda Civic Vti models (1993-1996) and the Accord Vti. These engines manage good fuel economy (6.5-7.0L/100km) while making a healthy 96kW of power from a 1.6L engine.

SOHC VTEC-E is found in a few of the early model Civic VEI's (1991-1993) and makes less power than the similar VTi but offers slightly better fuel efficiency.

DOHC VTEC is the ultimate performance monster and can be found in the Integra Vti-r (125kW), Civic Vti-r (118kW), Prelude Vti-r (147kW), Integra Type R (147kW), S2000 (176kW) and the NSX (206kW).

Cheatz
22-08-2003, 02:48 PM
Sweet... Good info :)

INFLYT
25-08-2003, 12:06 AM
It make's a great sound too. :lol:

Jnr Teggy
25-08-2003, 08:55 AM
meh! you don't need vtec to go fast!

wil
25-08-2003, 02:23 PM
u need this $$$$$$$$

wynode
25-08-2003, 03:39 PM
Keep it on topic please.

This IS the Tech section.

Calvo
25-08-2003, 08:25 PM
hey in the "where is it found" part, for SOHC ur forgettin the accord :D.
2.2L SOHC Vtc engines :P

wynode
25-08-2003, 08:59 PM
My bad.

Its fixed now :)

Calvo
25-08-2003, 09:01 PM
hehe thanks :D

Setanta
03-09-2003, 06:14 PM
I prefer this explanation I saw @ www.performanceforums.com :

k3nnis: Can you explain how VTEC feels like when it kicks in? Does it pin you back to the seat a little bit like a turbo?
sejanus: Imagine a incredibly tiny small turbo that for some bizarre reason takes 5500-6000rpm to make boost, and so small that it makes bugger all power, just an increase in noise

:twisted: :twisted: :twisted:

dc2r
03-09-2003, 09:02 PM
I know this is a tech thread, but is that guy just ignorant or what? he probably just got beat by a vtec so now he's knockin it, and he hasn't even tried it... he hasn't been in a type-r for sure....

Setanta
05-09-2003, 07:44 AM
I know this is a tech thread, but is that guy just ignorant or what? he probably just got beat by a vtec so now he's knockin it, and he hasn't even tried it... he hasn't been in a type-r for sure....

Ummm... it's humour :? :shock: :?

And no, somehow I don't think he was beaten by VTEC and got upset by it ;)

Personally, I think VTEC is over-rated by a lot of people, It's a means to an end for street cars to give them best of both worlds, but a turbo will do it better every day of the week and twice on Sundays :)

dc2r
05-09-2003, 12:38 PM
Well I can tell you that turbo is not everything. It's funny how a 4-cyl NA car can beat turbo powered cars in a straight line. I know vtec is over-rated, but it is also under-rated... if you know what I mean :)

Hadean
05-09-2003, 01:21 PM
Our family owns a couple of STi WRXs. One is a 2 door one and the only WRX i have driven.

Sure, turbo is great. But punting it around town is a headache. The turbo takes too damn long to spool. Sure, it makes up for it and then some, but you'd wait all day doing it. I had an old EF civic that was more responsive than that slug.

I like how people say there is such thing as 'vtec' lag. What lag? The car is N/A responsive already, N/A is more responsive than ANY turbo.

In a perfect world, you'd want a turbocharged car to have the responsiveness of the N/A AND have the linearity of power delivery of it as well. The reason why turbocharged vehicles give you that shove in the seat is because of non-linearity of the power delivery. It gives you more than what you expect. That's fine in the case of just driving around and perhaps the occasional traffic light GP, but for racing that is extremely undesireable.

It's really up to the buyer to decide what they want and what they prefer. We can talk about turbo vs n/a ALLLL day...

wynode
05-09-2003, 01:40 PM
It's really up to the buyer to decide what they want and what they prefer. We can talk about turbo vs n/a ALLLL day...

Exactly.

So lets keep this purely technical and VTEC related only.

Thanks.

dc2r
05-09-2003, 02:48 PM
Sorry, I knew that this was the tech thread, hence why my very first post in this had my apology. Anyone wanna make a Turbo vs NA thread? Let us know which section it should be in :D

Hadean
05-09-2003, 03:32 PM
Let's not... it's an eternal debate.

LatinoHatchCrap
10-09-2003, 12:32 PM
VTEC and turbo in the same line doesnt exist,,,turbo is different kettle of fish altoghether...VTEC its ok, but too many kids reckon its the ultimate :?

EG_2_TEG
26-09-2003, 02:04 AM
i know its a little off topic, but i'm a bit confused

i dunno whether its all VTEC engines, but in particular the B18C2 engine. many ppl say that you don't hear VTEC kick in, instead you hear the secondaries. :?

wynode
26-09-2003, 09:55 AM
Yeah, the B18C is more 'refined' than the b16 in that the VTEC change over is much smoother than the b16, where you feel VTEC kick in at 5,800 RPM.

EG_2_TEG
26-09-2003, 01:42 PM
i'm quite sure i read it on team-integra, but they say with the B18C, VTEC engagement point is somewhere along the lines of 4500rpm, and secondaries kick in at 5600rpm :?

wynode
26-09-2003, 02:17 PM
Yes, the initial engagement is at 4,500 RPM.

fried
31-10-2003, 02:35 PM
everyone says *oOoOoOoO dont u love thte sound of vtec rah rah rah*

im not sure i can hear *vtec*...? like to me, its a mind thing, i know i have vtec, so when i engage at certain revs, i feel confident knowing i ahve vtec, but i cant neccessarily *hear* it....

i do notice that the engine does get louder, but isnt that jsut cos its cranking higher revs etc?

can anyone explain this *vtec* noise? or yeah.... dum di dum di dum....

wynode
31-10-2003, 03:13 PM
Your exhaust is stock Eric. Once you have a loud(er) exhaust you'll notice it more ;)

Rowie
31-10-2003, 03:15 PM
yeh, you will hear VTEC for sure if you upgrade your exhaust and air intake :twisted:

joneblaze
31-10-2003, 07:45 PM
...i think those are two subtle hints eric....... :D *ahem*...EXHAUST......

MRJDM
17-08-2004, 01:01 PM
i was reading a article from doug (owner of hondata) he said once tuned you shouldnt really feel the vtec kick in. this is how apatos' car pulls now that it is tuned.

onabuzz
28-08-2004, 01:06 AM
ahh time for mini-me conversion :$

jords
26-06-2009, 12:18 AM
Damn old thread, good VTEC info!

ewendc2r
26-06-2009, 08:57 AM
Correct regarding VTEC transition once tuned --- Realistically there should be a tune of the Non-VTEC (dyno run) then a run of the VTEC Lobe only (Dyno run) then the two graphs compared. Where the lines cross, basically that is the best point for the VTEC crossover point as it maximises the area under the curve. This has an effect of softening the VTEC (instead of a kick) however rest assured, it is faster.

hectic_filo
26-06-2009, 10:24 AM
nice post there wynode.. keep it up

nice to know bout Vtecs

I have the SOCH VTEC 2.2 in my cd5 aerodeck Vti
and my dad has the vei EG VTEC-E 1.5 engine

Mice
01-07-2009, 08:50 AM
My engine makes a little tapping sound at idle, could it be these valves? Would driving it at higher rpm help it?

reedyek4
01-07-2009, 10:18 AM
VTEC....the fruits of brilliant engineering

cris88
15-07-2009, 07:17 PM
b18cr=tuff crossover :)

hectic_filo
23-07-2009, 11:41 AM
Yeah, the B18C is more 'refined' than the b16 in that the VTEC change over is much smoother than the b16, where you feel VTEC kick in at 5,800 RPM.

Where does the F22B1 or 2 not sure which 1 2.2ltr for the accord Vtec kicks in? at what RPM?