The main change between Perodua Viva and it’s predecessors (Perodua Kelisa and Perodua Kancil) would be their engines. Then it came the term of DVVT, and Perodua claiming their 1.3l DVVT saves fuel and provide power as same as normal 1.5l engines.

Let us get back to the basics, DVVT or it’s full name Daihatsu Valve Variable Timing is based (copycat) on Daihatsu mother company Toyota engine, which is VVT-i (Variable Valve Timing – intelligence). We believe that DVVT is just VVT-i’s engine brand name for Daihatsu cars.

DVVT and VVT-i is based by Yamaha’s YPVS (Yamaha Power Valve System). Yamaha was bought over by Toyota for it’s YPVS because Toyota afraid of losing to Mitsubishi’s MIVEC and Honda’s Vtec. Yamaha has been provinding Toyota and Daihatsu engines since.

DVVT and VVT-i engines are always put together to be compared with V-tec (Variable Valve Timing and Lift Electronic Control System), i-DSI (intelligent Dual and Sequential Ignition) that is developed by Honda earlier.

All of the Vs (DVVT, VVT-i, i-DSI, Vtec, CVCC, MIVEC, CVVT…) was meant to increase fuel efficiency which is to use less fuel and produce more power from the engine. The objective is the same, the only difference would be their methods.

DVVT and VVT-i

Normal engines is good in the low RPM. However, when the RPM reaches higher level, the amount of power produced per fuel is lesser. This is because the air from outside the engine couldn’t get into the combustion space in a short period of time. That’s what Yamaha sees, and they developed YPVS, VVT-i and DVVT.

DVVT and VVT-i valve works like a normal engine while in low RPM. However, as the RPM increases, the valve timer shifts the time of opening of the valve a little bit earlier. The higher the RPM goes, the earlier the valve opens.

By doing this, air would hav enough time to go into the ignition room, thus making the fuel burning in high RPM more efficient than conventional internal combustion engine.

Vtec

Vtec have the same idea with DVVT and VVT-i. It acts like a normal fossil combustion engine in low RPM, however when the user revs until certain limit (usuall 5000rpm). The valve timer would activate (this is what people usually calls Vtec change) and produce a noisy sound.

It sounds a little bit like a 2-stroke motorcycle engine revs high. You feel like the torque suddenly increases and you have more power to accelerate.

What actually happens is that the valve intake open longer than normal. Allowing more air to come into the combustion chamber. The more air in the chamber, the more efficient the fuel burns.

i-DSI

i-DSI is a new technology by Honda. Instead of changing the valve timing of an engine, Honda put two spark plugs on each piston. The reason is the same.. to burn the fossil more efficiently.

These spark plugs however have the main and secondary plugs. The main plugs usually sparks first, followed by the secondary plugs to burn the remaining gas in the chamber.