There are a variety of techniques used to increase the volumetric efficiency of an engine. Variable Valve Timing (VVT) is one of them, that accounts for varied timing of the intake and exhaust valves, relative to the engine requirements, with conduciveness. This is solely responsible for the optimised performance, when in cruising, high load, etc., This results in more efficient power delivery.
The valve timings vary in a VVT engine while keeping in sync with the engine speed ensuring the valves opening as per the need of the engine load. All this, actually brings about a change and improvement in the engine efficiency, power, and performance.
DIFFERENT VVT MECHANISMS
Nowadays, VVT is available in all over the spectrum of cars. Each and every automobile manufacturers have their own version of variable valve timing. With some minor tweaks that is best suited for their requirements, they roll-out this technology mainly considering the efficiency boost that VVT has to offer. Patents of some car manufacturers that roll out their product in India are listed below.
- Variable Timing Valve Train (VTVT) – Hyundai
- Variable Valve Timing (VVT) – Maruti Suzuki
- Twin independent Variable Camshaft Timing (Ti-VCT) -Ford
- Variable Valve Timing with Intelligence (VVT-i) – Toyota
HOW VTEC IS DIFFERENT FROM VVT?
VTEC is an acronym for Variable valve Timing and End lift Control. It is quite catchy, but we have to admit that it is a tortured one, though. As its name suggests, it is a combination of Variable Valve Timing (VVT) and Valve lift control. VTEC was first introduced in ACURA NSX in America (and as HONDA NSX to the rest of the world) in the year 1989. This made them pioneer in that field. Even now, only BMW and PORSCHE have their own technology for valve lift control. It is very much efficient when compared to normal VVTs.
WHAT VTEC ACTUALLY IS?
To explain VTEC better, we have to jump right into the basics of automotive valve system. Generally, ICE are Air-breathing devices. It requires adequate air to impart power to the vehicle. Both the intake and the exhaust waste gases are controlled by the valves. These are in turn actuated by camlobes present in the cam shaft. Crankshaft drives the camshaft by a belt-drive mechanism. These lobes are eccentrically shaped and have high points that opens the valve. This determines how long the valves gonna open and how much its going to open.
This cam lobe is the key to determining the engine performance characteristics. It sets the parameter with which the engine’s going to breathe.
Here, VTEC uses THREE cam lobes per cylinder on the intake side. The two cam lobes that are present on the either sides are called PRIMARY CAM LOBES. This is with which the engine operates at lower RPM range i.e., generally upto 5000 rpm. Once it exceeds the limit, hydraulic oil pressure gets surged inside the cam shaft and pushes the pin to connect all the three lobes together. Now, the VTEC lobe present in the middle pushes these lobes down. This leads to wider opening of the valves at higher RPM mode. Hence, better power is obtained.
VTEC EVEN HAS GOT MEMES!!
The two things that VTEC engines gave that others didn’t were
This was revolutionary when the time it was launched. All of a sudden, camaros and mustangs were getting heat from CIVICs!! It got famous within a short period of time. This is probably the only automotive technology that has got memes!! 😉