![]() ![]() When the engine is cold, timing can be delayed and late fuel injection is designed to be combined with earlier valve openings so that the catalytic converter can reach operating temperature more effectively. The spark occurs at a point between 0.002 seconds and 0.0002 seconds, which is 10 to 100 times faster than a single hummingbird wing flap. This timing all happens in such short order that you can’t actually see it in action unless you’ve got the vehicle torn apart and know what you’re looking for. This usually advances during the lighter load operations so that lean air-fuel mixtures don’t create knocks in the engine. Ignition timing is another part of this equation. High RPM and tremendous power combine to deliver impressive low-end torque that’s just as impressive as the performance that you’re getting. In a dual system, the exhaust valves are activated in addition to the intake, which helps minimize stop/start pressures and ensures premium performance.Īdjusting the overlap sequences between your intake and exhaust valves also allows you to enjoy maximum scavenging of the intra-cylinder charge. With dual or single timing, the same thing happens. When the VVT activates, oil pressure will be exerted on an actuator that presses the camshaft slightly, helping engage the “performance” setting. The VVT has an economy profile (below 6,000 rpm) and a performance profile (over 6,000 rpm). Even a single VVT, though, can be an economical upgrade to help save on fuel emissions and help the engine “breathe” more effectively. At high speeds, you’ll enjoy premium horsepower without the excess noise and vibrations that some older vehicles have.ĭual VVT also offers reduced emissions at the same time it’s providing you with excess power, so it gives you the best of both worlds. It also offers greater torque at low speeds without the risk of engine knocking. By adjusting the timing of the valves, you can generate more power, better fuel efficiency, and even reduced emissions. Dual VVT: Varies the timing of the intake camshaft and the exhaust camshaft.Įssentially, the dual VVT system creates a solution that helps the engine breathe more efficiently.Single VVT: Continuously varies the timing of your intake camshaft (only).Below, you’ll see the two main types of VVT engines and what each entails. When you adjust the valve gears and controls, the adjustment will change the duration of valve lifts, which are responsible for controlling the intake and exhaust. However, oil pressure makes it easy to separate the gears, allowing them to change their relative speeds and help change the speed of the camshaft. When normal driving conditions are engaged, the cogs are meshed together and turn at the same rate. The system is comprised of gears that are placed one inside the other, an inner gear that connects to the camshaft, and an outer gear that connects to the chain or drive belt. When you add in modern electronics, controls to optimize valve events, and premium fuel injection, it all comes down to precision that can’t be more than a millisecond off or it could ruin the entire engine’s operation. The engine needs to monitor timing in order to handle all the variables of combustion, and without a conventional time scale, you can see just how quickly things actually move when you fire up the engine. In addition to sensors, there are physical mechanisms that help control the characteristics and behavior of the valves. In order to monitor all of this, various sensors are responsible for feeding information to the ECU, or the computers onboard. Finally, VVT also affects the valve lift, which is how far the valves actually open. ![]() Then, there’s the duration, which refers to how long the valves remain open (or closed). It’s responsible for valve timing, or when the valves open and close based on the points in the piston’s movement. Variable valve timing is responsible for controlling three elements of the intake and exhaust valves. Variable Valve Timing, Car and Driver, 2021 What Does VVT Control? The whole system seems complex at first, but it’s not really that difficult to understand.įirst, let’s take a look at this graphic from Car and Driver that shows what a VVT engine looks like. Making adjustments in the overlap time between when the intake valve opens and the exhaust valve closes can help improve your engine efficiency. The system might rotate the camshaft either forward or by slowing it. There may be other actions that occur during this process. Over the years, manufacturers have developed several different designs and technologies related to this system to help control the timing and impact how long the exhaust and intake valves remain open. In this instance, variable valve timing, or VVT for short, is used primarily for emissions control and performance. The timing system in a vehicle is responsible for ensuring that the engine fires properly.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |