How a Turbo works

this was my senior paper back in highschool, teacher didn't like it because "it wasn't following the format that was required". i had to use the term race-cars in some situations, i apologize.

Here I will explain how the basics of a turbo works along with the general knowledge of a normal combustion engine runs, I will also tell you the different parts and other information. Turbochargers and superchargers increase engine efficiency, effectively giving you more horsepower and torque. Turbochargers and superchargers are based on forced air induction. They basically cram your engine with more air. I will only refer to the word "turbocharger" in this paper, but understand that a supercharger works in a similar way, and the difference between them is the supercharger is belt driven (hooked on to the rest of your engines belts) rather than exhaust driven like a turbo charger.
First off, we need to have a basic understanding as to how an engine works. If you've ever used a lighter, you already know what happens when you combine a flammable substance with air and a spark (boom). Now if you add more air and more fuel with the same spark you'll get a bigger explosion (BooM). Finally if you add more fuel, more air and compress it into a small space, using the same spark, you'll get a rather large and powerful explosion (KABLAM).
Take that concept and apply it to the way your engine produces power. A gasoline engine combines air and fuel into a cylinder, seals it off, compresses it and ignites it. The force of the explosion pushes the piston down, which in turn pushes the connecting rod, turning the crankshaft, then to turning the drive shaft, and finally to the wheels turning them so you move.
Back to our concept of adding fuel and air to a relatively small space and igniting it... The more fuel and air you can get in the cylinder, the bigger the bang. Have you ever noticed that your vehicle drives better on a cool evening than on a blistering hot day? This is usually because cooler air has more molecules in a given area (they move slower so you can catch more in a certain area) than warmer air (moves faster so can’t catch as much). Cooler air means more air molecules compressed in your cylinder, means your in car computer (also commonly referred to as your ECU) will inject more fuel into the cylinder, means better combustion and power.

Parts to a Turbocharger
A turbo charger has two main parts all connected to the center section, the housing over the turbine (usually made of cast iron, on the side after the air flows through the engine.) and the housing over the compressor (usually made of cast aluminum, and is on the side bringing air into the engine). These are referred to as the "turbine housing" and the "compressor housing," respectively. Exhaust coming from your engine gets routed through the turbine section of the turbocharger, spinning the turbine wheel. The turbine wheel is connected to the compressor wheel by a rod, and when the turbine wheel spins, it spins the compressor wheel. The compressor takes in air from the outside (through the air filter) and forces it into the intake of your engine.
Some other parts must not be left out and are essential to a good running turbo. An Intercooler is a necessity because it cools down the pressurized air brought in from the compressor before the air actually enters the engine. A B.O.V. or otherwise known as a blow off valve prolongs the life of a turbo. During shifts the pressurized air can sometimes surge back into the turbo creating too much pressure. What the B.O.V. does is it releases the pressure during those shifts preventing that surge of unwanted pressurized air. A turbo by itself does not know how to regulate boost levels. Basically, a turbo system works like a loop meaning that the engine's exhaust spins the turbo which, forces more air into the intake making more exhaust which, in turn spins the turbo even faster. Without a way to regulate boost levels the turbo would keep producing higher pressures until the engine exploded. When the desired boost level is reached the wastegate opens and vents pressure from inside the manifold (connects the exhaust side of the engine to the turbine section) so the turbo won't spin any faster.
The "boost" you get from your turbocharger is measured in psi. Generally a turbocharger will give a boost of between 4-8 psi, though engines in racecars and high-end production cars can have up to 30 psi. With the added air going to your engine, the computer will inject more fuel in as well creating more powerful explosions in the cylinders. This means more power and engine output.

Down side to Turbo charging
Depending on boost levels, you will have to use higher octane (91+) fuel, this is to stop and/or avoid “knocking”. Knocking is also known as misfiring, it’s when the fuel and air mixture is too high from the compression and it ignites without the spark. Too much knocking can result in minor to major engine damage including a blown piston or even detonating the whole engine in extreme situations. So this could be the death to any engine but since the turbo is forcing (compressing) for air into each cylinder the risk is greatly increased if not taken care of. Racecars often replace the pistons and rods with high strength forged pieces strong enough to hold the extra pressure needed to run high boost under hard driving. Most factory cars that come from the factory turbocharged are designed to run day to day without any severe consequences.
A major downside is Turbo lag, which all turbos have, but vary due to the different sizes of the turbochargers. Turbo lag is when the fans are rotating but by the force of the turbine wheel (exhaust flow) this happens at low RPM until the compressor wheel can sustain the turbo from enough air being pushed into the engine to power the entire turbo, sort of like a self sustaining reaction. Usually the self-sustaining mark is around 3,000 RPM but that mark is reached sooner for smaller turbochargers, and takes longer for larger turbochargers. Then when that mark is reached is when the power is gained because of the more air into the engine. On smaller turbos the turbo lag is short because it spins up faster due to the smaller wheel and not much air is needed to push the fans. Even though the power is made quicker on a smaller turbo the down side is that it cannot hold that much boost/pressure so the power generated is limited. On a larger turbo the fans are larger so has more turbo lag because of the large amount of energy needed to push the larger fans, but the plus side is even though it doesn’t create much power until higher RPM once it does create power it creates a lot of it, and can sustain higher boost levels over a smaller turbocharger, drag cars and racecars often use larger turbochargers because of the large amounts of power generated from them. Sometimes if the financial side of things is good then a twin turbo charger set-up is an option. This set-up uses two different turbochargers, one smaller one and one larger one so you can get boost through out the entire RPM range.

Car Companies that Have turbocharged cars from the factory
Different car companies use different brands of turbochargers. Some of the brands are independent and some are made by the Auto manufacturer themselves. In the import scene some companies make their own turbo kits to put on existing models like Hondas, Mazda, Nissan, Toyota, and others. This list is for the different turbochargers that come on the engines straight from the auto manufacturer.
Audi: KKK/BorgWarner KO-series
Dodge: Mitsubishi TD-series and Garrett T25
Mazda: Mostly in house Turbos
Mitsubishi: Mitsubishi TD-series and Garrett T25
Nissan: Garrett T25 ad T28
Subaru: IHI
Toyota: Toyota CT-series and Mitsubishi TD series
Volkswagen: KKK/BorgWarner KO- series

Turbo over view

Turbo chargers have been around since the 1920’s where they were put into a limited amount of fighter aircrafts looking for increased speed over rival nations. Since then the turbo has been used on a variety of different applications such as diesel engines, boats, rotary engines, and piston engines. The turbochargers’ first patent was in 1905 when the Swiss engineer Dr. Alfred J. Buchi developed a practical version, not much unlike that of what we see today. In recent years turbochargers have had a sharply increased in popularity because of the popular underground racing culture started or rather brought to the spotlight by the movie “Fast and Furious” who’s cars seemed to make obscene amounts of horsepower in almost an alter reality. Over night people began to see the possibilities for turbo charging small displacement engines to create great amounts of power. Honda was the base platform and soon companies swarmed the market with custom turbo kits that the public swallowed with great enthusiasm. Now more and more companies are coming up with new innovative ideas and increasing the efficiency of turbochargers. Turbo charging is a unique art that provides a lot of power out of a smaller engine.

 

yes it was for English class, and know it wasn't well written, i was just trying to get the information across.

and yes i got off easy......however there were a couple of other final papers due. (current issue debates, that kind of thing.)

hope it helps someone on here