We’ve all seen a “VTEC just kicked in, yo!” meme at some point while browsing the internet, and here’s an excellent demonstration of Honda’s Variable Valve Timing and Lift Electronic Control system in operation.
This video comes courtesy of Dan M Henderson, who shot it by mounting a camera in the engine bay of his friend’s Honda NSX, which has been modified to feature individual throttle bodies (ITBs) in place of the stock induction system for the 3.5 litre naturally-aspirated DOHC VTEC V6 engine under the bonnet.
The minute-long clip is purely to meant to satisfy the ears of those who enjoy hearing the transitional phase of the VTEC system, with the ITBs making it even more audible as the engine switches to a more aggressive camshaft profile at higher engine speeds.
If you’re curious how VTEC works, an engine’s camshaft has lobes that control how much the valves open to let air in. The greater the lobe’s height, the more the valve will lift to allow more air into the combustion chamber, and with more air, the engine can use more fuel to make more power.
The VTEC system features multiple lobes that allow for separate camshaft profiles, with the lower profile meant for low engine speeds to provide efficiency. This is shown in a video by Engineering Explained, where the two rocker arms representing the lower profile, pushes on the valves and are disconnected from the centre rocker arm.
However, at higher engine speeds where the higher profile is required, oil pressure forces a piston to lock the centre and outer rocker arms together, enabling the higher cam profile that allows more air into the engine. This transition is where you hear that signature VTEC sound.
Modern Honda cars now come with i-VTEC (Intelligent Variable Valve Timing and Lift Electronic Control), which adds on Variable Timing Control (VTC) to the VTEC system, allowing the intake camshaft to be continuously variable to further improve efficiency.
This system is found even on lower-end Honda models, although the difference in cam profiles isn’t as glaring as it used to be, which dilutes the “VTEC scream” and kick in the back feeling of earlier VTEC systems.
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