How Honda's VTEC Engines Work and How VTEC Can Kick In, Yo

Illustration for article titled How Hondas VTEC Engines Work em/emand How VTEC Can Kick In, Yo

Honda’s Variable Valve Timing & Lift Electronic Control system, known as VTEC instead of the more accurate VVTLEC, is one of those things that various parts of automotive pop culture have glommed onto, and as a result, almost everyone with even a passing interest in cars is aware of VTEC and its propensity to kick in, yo. While it’s widely understood that it has to do with valve timing, do you know exactly how it works? Engineering Explained does, and they’re here to, you know, explain.


Fundamentally, VTEC is a technology that deals with an engine’s intake and exhaust valves, controlling the volume (and speed) of the gases that enter into and exit the cylinders. The ‘V’ in VTEC means “variable” because unlike most engines that have a set amount the valves open, VTEC-equipped engines can choose between two different amounts that the valves open.

Illustration for article titled How Hondas VTEC Engines Work em/emand How VTEC Can Kick In, Yo

The way VTEC does this is via a camshaft that has two different cam profiles that open the valves. At lower speeds and engine revolutions, the two small outer cams actuate the valves, but at higher speeds/RPMs higher oil pressure is used to force a piston to lock rocker arms together and, when locked, have a surface that contacts the high-speed center cam, which provides for greater valve opening sizes.

It’s all explained an animated very well here, so you may as well just watch it:

I suppose the big takeaway here is that, since VTEC is essentially a binary low/high variable cam system, there sort of is a point where VTEC can actually “kick in” at least if you define “kicking in” as “oil pressure getting high enough to force a piston to move into a position where the rocker arms are actuated by the center cam of the three-cam group per cylinder on the crankshaft.”


Senior Editor, Jalopnik • Running: 1973 VW Beetle, 2006 Scion xB, 1990 Nissan Pao, 1991 Yugo GV Plus, 2020 Changli EV • Not-so-running: 1977 Dodge Tioga RV (also, buy my book!:

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Hayden Lorell

I think everyone has gone over how VTEC works about 50,000 times on youtube. Can we cover another VVT system? Like Toyota and their old Celica engines from the early 2000s? People used to describe those as having a normal cam and a power cam but is that actually how the system worked? Or what about the VVT they implemented on the 2JZ, what made that special?