How VTEC works

The DOHC i-VTEC system (one of the two cams shown). Found in the Honda/Acura K series, F20C and F22C1 engines, the i-VTEC system uses roller rockers, continuously variable intake cam timing (VTC, not shown) and three separate cam profiles for both the intake and exhaust valves of each cylinder. These features improve power and efficiency of the engine across its entire rpm range.

Below 5,800 rpm the offset and low lift of the valves aids in fuel atomization. This provides improved low end torque and fuel efficiency by creating a powerful swirl in the cylinder and by keeping the intake air charge at high velocity. Above 5,800 rpm a high lift, long duration cam profile is engaged by the synchronizing pistons to provide greatly improved high rpm power and torque.

Category:

Autos & Vehicles

Tags:

• Honda
• VTEC

[gonerogue]

Is it normal for 2 "like" valves (intake or exhaust) in a 4 valve configuration to be on different timing? The reason I ask is because before VTEC kicks in for this demo, the valve lift from the two smaller lobes is on different timing. After VTEC kicks in, the lifting is in sync.

[idontcare80]

The lift and timing between the two intake valves is offset. The reason for this is in the video description. It is a feature that is unique to VTEC engines and possibly some of the other engines equipped with a cam changing VVT system.

[notyourfriendbuddy]

@idontcare80

I recently bought a '99 civic w/ a recycled LKQ engine from an '01. The previous owner claimed it's VTEC. How do I know for sure, short of taking it to a shop? Would a Haines Manual have the info?

Your knowledge and expertise is needed.

[idontcare80]

@notyourfriendbuddy

LKQ engine?

You can just pull the valve cover and look for the VTEC rockers.

[Fauket]

This sistem is the VTEC-E

[idontcare80]

It's i-VTEC. It has rollers and has three lobes per cylinder, per cam. Only one cam is shown here.

[wildbloodydragon]

Best demonstration ever. No article could ever explain it any better then this.

[civicturbo1976]

but japs got it right

[MikeHawk1234567890]

No words needed, because I don't want to listen to some asshole shitting out words.

[BRYAWN]

@gonerogue

it is to make swirl (I don't know why, I want to answer on youtube tonight...)

[man710r]

11 people don't have VTEC

[pepene93]

@xXxDANMANxXx well, the low RPM cam profiles create better low-end torque, and much better fuel economy. on some cars, it does kick in lower, and i suppose you could make it come in whenever you want if you knew what you were doing (not sure about that one)

[drekotrance]

Nice demontration of the system

[xXxDANMANxXx]

ooohh i think i get it now, hard to explain my question before but i always wondered, why not just make the vtec come in at like 4,000 rpm? or a lot lower ( i know theres a good reason for it but im not quite sure why )

[Robcicle]

@wildbloodydragon video explination is always better

[0spaceboy]

that lsv and b20v bullshit ant all that if it was honda would had dont it a long time ago.

[Blackgam3r]

As long as the logo stays the same, so will Ford's image of how they used to make crappy cars.

I don't have a problem with the current logo but a logo change with a different Font and similar colors would get people to notice a "new Ford".