Techniquest Glyndr’s ZR engine with intelligent variable valve timing, shown in a cutaway view.
Toyota created the variable valve timing technology known as VVT-i, or variable valve timing with intelligence, for use in automobiles. The Toyota VVT-i system takes the place of the Toyota VVT, which was available on the 4A-GE engine’s 5-valve per cylinder starting in 1991. The VVT system is a two-stage cam phasing mechanism that is hydraulically regulated.
VVT-i, which debuted on the 2JZ-GE engine in 1995 for the JZS155 Toyota Crown and Crown Majesta, modifies the interaction between the intake camshaft and camshaft drive (a belt or chain). An actuator is subjected to engine oil pressure in order to change the camshaft position. Engine efficiency is increased by adjusting the gap between the opening of the intake valve and the shutting of the exhaust valve. [1] Subsequent variations of the system include included VVTL-i, Dual VVT-i, VVT-iE, VVT-iW, and Valvematic.
In This Article...
A VVT-i engine: is it good?
advantages of VVT Utilizing VVT has a lot of advantages and hardly any disadvantages. One advantage is a 25 percent increase in maximum engine speed, which results in more peak power. Additionally, low speed torque is boosted, improving driving dynamics. You might believe that having an overlap between the intake and exhaust valves is unproductive because it signifies that exhaust gases are reentering the cylinder. Exhaust gas recirculation (EGR), on the other hand, is a crucial component of emission control and can be improved with VVT. The engine becomes more efficient when operated at medium speeds with a light engine load, such as when traveling on a highway, where maximum overlap typically occurs. The exhaust gas recirculation lowers the quantity of fuel required to power the engine, increasing the crucial MPG figure.
The extra expense and complexity of installing VVT in an engine is the sole negligible disadvantage. There are various approaches of adding VVT, and each manufacturer has a unique modificationsome are easier and less expensive to implement than othersthat they use. Regardless of design, improved fuel economy and power output are more advantageous in the long run than any up-front costs, especially when considering the multi-year investment in an automobile.
Does the typical motorist understand anything from all of this fancy talk? Most likely not, but it might offer you a question to put to the salespeople the next time you’re looking for a car. Fans of racing and high-performance vehicles will undoubtedly be curious to learn how various VVT technology might impact the output of their engines. One thing is certain: manufacturers will continue to come up with innovative and affordable ways to incorporate VVT into regular cars as the requirements for fuel efficiency are further mandated.
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What makes VVT and VVT-i different from one another?
VVT-i is a smart application of the VVT technology that I previously described, employing microprocessors to control the VVT functionality through a few actuators. Toyota created VVT-i, which began using it in 1996 and brought changes to the timing of the intake and exhaust valves. The Toyota VVT technology, which was introduced in 1991 for 4A-GE engines, was intended to be replaced with this variable valve timing technology for automobiles, which is somewhat comparable to BMW’s VANOS.
By adjusting the mechanisms between the camshaft drive (belt, chain, etc.) and the intake camshaft, the technology is to blame for differences in the timing of the intake valves. The engine oil pressure that is applied to the actuator to change the camshaft position serves as the adjustment’s medium. Higher engine efficiency is the result of adjustments made to the gap duration between the opening of the intake valve and the shutting of the exhaust valve. Since the release of VVT-i, a number of variations of this system have been developed, including VVTTL-i, Dual VVT-i, VVT-iE, and Valvematic.
What does the VVT-i sensor do?
A part of the variable valve timing system that controls oil flow based on engine speed and load is the variable valve timing solenoid. Performance and fuel economy are improved by a functioning VVT solenoid.
How can I tell whether my VVT is functioning?
The engine will also misfire or appear to stumble if your VVT switch is malfunctioning while your car is carrying extra weight, going up hills, or when you press hard on the accelerator to accelerate quickly. This is frequently brought on by a switch’s electrical malfunction rather than always by the switch itself. It’s likely that the variable valve timing switch won’t need to be replaced if you identify this issue and call a nearby ASE-certified repair to evaluate the situation. However, a correct diagnosis is required to confirm that it is an external issue. The likelihood of future engine damage will rise if you ignore the issue.
Regardless of the exact cause, you should always be proactive and get in touch with a qualified mechanic as soon as you observe any of the aforementioned warning signs or symptoms. The possibility that a problem can be fixed without resulting in further harm to other engine components greatly improves if you identify it as soon as the symptoms appear. As soon as you see any of these symptoms, call a local YourMechanic experienced mechanic.
Dual VVT-i: What is it?
Toyota consistently incorporates new technological developments into all of their products. Dual VVT-i (Variable Valve Timing with Intelligent) technology is their most recent use. The use of technology could increase engine efficiency and eco-friendliness.
The system, which serves as an automatic timing controller for the engine’s inlet and exhaust valves, is mounted on the cylinder head. Modern 4-stroke engines have intake and exhaust valves to regulate the flow of the fuel and air mixture into the combustion chamber and out the exhaust pipe.
The valve timing could be modified based on engine needs by using VVT-i. This technique was formerly solely used on intake valves. It later added the ability to control the exhaust valve. And so the Dual VVT-i system came into existence.
Engine performance will improve as a result of managing air flow, emissions, and the inlet and exhaust pipes under any circumstance. As an illustration, when starting the engine, it might maximize the control to get the engine to the right temperature. The ability to instantly access engine power and torque is a benefit. However, the catalytic converter could reach a hot temperature more quickly, allowing it to filter emissions more effectively and environmentally friendly.
Not to be forgotten is the possibility of adjusting the exhaust valve with engine rotation after the engine has reached operating temperature. Of course, the scene should alter depending on whether we are cruising down the highway or stuck in a traffic congestion.
It is hardly surprising that, despite having a similar capacity, Toyota’s power source today offers higher performance and efficiency. For instance, the 2ZR-FE 1.798 cc four-cylinder 16-valve engine in the Toyota Altis can now produce 190,2 Nm of torque and 151 dk of power at 6.400 rpm. more potent, but more affordable and environmentally friendly
Which is preferable, VVT-i or VTEC?
The intake and exhaust valves in an automobile engine are moved by a camshaft. The configuration of the lobes that move the shaft determines the timing, lift, and duration of the valve. Lift describes how much a valve is opened, whereas timing describes the angle at which it is opened or closed in relation to the position of the piston.
While VVTi simply employs the timing aspect of the valves, i-VTEC uses both the timing and the lift aspect.
VVTL-i, a technique created by Toyota that uses timing and lift aspects, is comparable to Honda’s i-VTEC.
In 2001, Honda debuted i-VTEC technology to their four-cylinder K-series engine family. This technique allows
- When the engine is running, the intake camshaft might advance by 25 to 50 degrees.
- A computer-controlled, oil-driven adjustable cam gear implements phase changes.
- Phasing can be totally retarded at idle to considerably accelerated at full throttle and low RPM depending on the engine load and rpm.
- Further torque output optimization results, particularly at low and middle RPM.
- There are still only two separate low-RPM and high-RPM profiles for valve lift and duration.
- By altering the connection between the intake camshaft and camshaft drive (belt, scissor-gear, or chain), the timing of the intake valves can be changed.
- An actuator is subjected to engine oil pressure in order to change the camshaft position.
- Engine efficiency is increased by adjusting the gap between the opening of the intake valve and the shutting of the exhaust valve.
How reliable are Toyota dual VVT-i engines?
Variable Valve Timing with Intelligence is referred to as VVT-i. Toyota created the technology to automatically and constantly change the intake valve timing to enhance engine performance. The capacity of the system to recognize driving circumstances, such as acceleration or travelling up or down hills, is referred to as the “intelligent element of VVT-i.
Dual VVT-i technology from Toyota improves system performance and helps to further reduce emissions by adjusting both the intake and exhaust valves.
More power, better responsiveness, better mileage, and lower pollutants are the practical results for the driver. Another example of how advancements in engine technology are making cars stronger, cleaner, and more effective is VVT-i.