Since the late 1980s, carburetors have been almost completely replaced by fuel injection, a far more sophisticated and effective system of mixing fuel and air. Aluminum weighs far less than iron — typically, an aluminum engine weighs half what an iron one weighs. But they also make engines far more complicated, and can make them tricky for weekend mechanics to work on. The benefit to the overhead cam setup is that it allows for more intake and exhaust valves, meaning fuel, air and exhaust can move more freely through the engine, adding power. On an overhead cam setup, the camshaft is much smaller and is inserted above the cylinder head itself, rather than in the engine block. There’s one on a single overhead cam (SOHC) engine, while a DOHC engine has two. The term refers to the number of overhead camshafts above each cylinder in the engine. The drawback of having overhead cams is that they increase complexity and cost. They do have drawbacks in terms of their increased complexity. In some ways it makes gasoline-powered engines more similar to diesel engines, which have always used a form of direct injection. Next up: Let’s learn why diesel engines aren’t the smoky, noisy, low-power oil burners of the past.

Next up, we’ll discuss why carburetors have practically become a thing of the past thanks to fuel injection. Computer-controlled fuel-injected engines are easier to start, especially on cold days, when carburetors could make things tricky. However, they have become the industry standard for fuel delivery, and it doesn’t look like carburetors will be making a comeback anytime soon. The ECU makes sure processes like ignition timing, the air/fuel mixture, fuel injection, idle speed, and others operate the way they’re supposed to. Many engines now incorporate some form of variable valve timing, often controlled by the engine’s on-board computer. Despite these issues, direct injection is the hot new technology in the automotive world right now. In this next section, we’ll discuss the next step in fuel injection technology known as direct injection. By making the engine run more efficiently, engine computers can result in greater fuel efficiency and easier diagnosis of problems. Sometimes, direct injection engines can exhibit the buildup of carbon deposits on the intake valves, which could cause reliability issues. On a direct injection engine, fuel is sprayed directly into the combustion chamber, not into the air intake manifold. That mix is brought into the combustion chamber by valves on each cylinder during the intake process.

Fuel injectors spray gasoline into the air intake manifold, where fuel and air mix together into a fine mist. Road salt is just a non-purified version of regular salt, with more minerals in the mix. This makes an engine more flexible and allows it to deliver peak performance in a variety of conditions. It’s made of durable, dishwasher-safe plastic and comes in a variety of colors. Many early aluminum block engines had problems with cylinders warping, leading to concerns over durability. Camshafts are part of your car’s valvetrain, which is a system that controls the flow of fuel and air into the cylinders. These chemicals are a significant threat to the health of our rivers, lakes, and streams — and to individual health too. Taking water directly from streams or purpose built dams are a common means of supplying water to farms in New Zealand. There are times when an engine requires more air flow, like during hard acceleration, but a traditional engine often does not allow enough air to flow, resulting in lower performance. In addition, high-performance cars like the Porsche 911 Turbo or Corvette ZR-1 use forced induction to achieve tremendous gains in power.

Other computers in the car control things like electrical systems, airbags, interior temperature, traction control, anti-lock brakes and the automatic transmission. Toyota has one they call VVT-i, for variable valve timing with intelligence, and BMW has a system called Valvetronic or VANOS, which stands for variable Nockenwellensteuerung, meaning variable camshaft control. Next we’ll learn more still about how valves affect performance when we talk about variable valve timing. Large infestations (more than 10 square feet or 0.9 square meters) might require professional mold removal. Today the majority of all new small engines use aluminum instead, though many large V8 engines still use iron blocks. More and more companies are starting to increase their use of direct injection, but it has yet to become the standard. For countries within the European Union, water-related European Union directives are important for water resource management and environmental and water quality standards. And with fuel economy and emissions standards getting stricter, many carmakers are turning to forced induction on smaller engines instead of building larger engines. As we learned earlier, direct injection engines boast an increase in power and fuel economy over stand fuel injection systems.