Intake, induction or suction: The intake valves are open as a result of the cam lobe pressing down on the valve stem. The piston moves downward increasing the volume of the combustion chamber and allowing air to enter in the case of a CI engine or an air fuel mix in the case of SI engines that do not use direct injection. The air or air-fuel mixture is called the charge in any case.
Compression: In this stroke, both valves are closed and the piston moves upward reducing the combustion chamber volume which reaches its minimum when the piston is at TDC. The piston performs work on the charge as it is being compressed; as a result its pressure, temperature and density increase; an approximation to this behavior is provided by the ideal gas law. Just before the piston reaches TDC, ignition begins. In the case of a SI engine, the spark plug receives a high voltage pulse that generates the spark which gives it its name and ignites the charge. In the case of a CI engine the fuel injector quickly injects fuel into the combustion chamber as a spray; the fuel ignites due to the high temperature.
Power or working stroke: The pressure of the combustion gases pushes the piston downward, generating more work than it required to compress the charge. Complementary to the compression stroke, the combustion gases expand and as a result their temperature, pressure and density decreases. When the piston is near to BDC the exhaust valve opens. The combustion gases expand irreversibly due to the leftover pressure?in excess of back pressure, the gauge pressure on the exhaust port?; this is called the blowdown.
Exhaust: The exhaust valve remains open while the piston moves upward expelling the combustion gases. For naturally aspirated engines a small part of the combustion gases may remain in the cylinder during normal operation because the piston does not close the combustion chamber completely; these gases dissolve in the next charge. At the end of this stroke, the exhaust valve closes, the intake valve opens, and the sequence repeats in the next cycle. The intake valve may open before the exhaust valve closes to allow better scavenging.
Each fuel has its supporters and detractors. Experts automotive industry can give many reasons for allowing the selection of a suitable fuel for our car. However, not always the cheapest solution turns out to be the best for driver or car owner. For example, if you want to consider the option of supplying gas in our car, we must know that it is necessary to install proper installation. This is connected with considerable costs, but on the other hand, avoids the higher fees in the future. However, a group of drivers who decide to change their system already installed in your car, however, is quite sparse.
What to buy a gift for fans of the automotive industry? Contrary to appearances, the possibilities are really a lot. We can decide to choose the professional literature, which concerns a favorite of the recipient by the model or brand of the car. When you want to select a small gift, certainly a great idea is to choose a key ring or other gadget that the person receiving the gift from us can be attached to keys to the car. Very nice idea on the web, but also a fun gift for a fan of the automotive industry is a shirt with an appropriate inscription. Here we can choose a really different graphics and manufacture of t-shirts with fun prints more than one person can really surprise. This t-shirt is a cool gift for a friend, brother or boyfriend.