How does a Supercharger Work?

Answer

A supercharger works by using a belt driven pulley to turn a turbine that forces air into the combustion chamber of an engine. The increased amount of air allows an increased amount of fuel to be injected in the engine, the result is a substantial in

&A Related to "How does a Supercharger Work?"  How do Superchargers Work ? A supercharger is a great way to add more horse power to your car. The better a car can breathe meaning air intake the faster it will be able to go.http://answers.ask.com/Vehicles/Autos/how_do_super...

  how does a supercharger work on a motorcycle? The supercharger uses a compressor to draw far more air into the cylinders of the motor than would enter them at normal atmospheric pressure (as in the case of a carburetor or fuelhttp://www.ehow.com/facts_7605100_supercharger-wor...

  How does a supercharger in a car work ? Basically it is a compressor that is forcing more air into your engine. However, it is not that simple. When you add more air you have to add more fuel to burn that extra air. So

Overview and need of a supercharger

Since the invention of the internal combustion engine, automotive engineers, speed junkies and racecar designers have been searching for ways to boost its power. One way to add power is to build a bigger engine. But bigger engines, which weigh more and cost more to build and maintain, are not always better.Another way to add power is to make a normal-sized engine more efficient. You can accomplish this by forcing more air into the combustion chamber. More air means more fuel can be added, and more fuel means a bigger explosion and greater horsepower. Adding a supercharger is a great way to achieve forced air induction.

What is a Supercharger?

A supercharger is an air compressor used for forced induction of an internal combustion engine .

Supercharger

The greater mass flow-rate provides more oxygen to support combustion than would be available in a naturally-aspirated engine, which allows more fuel to be provided and more work to be done per cycle, increasing the power output of the engine.

Power for the unit can come mechanically by a belt, gear, shaft, or chain connected to the engine's crankshaft.

When power comes from an exhaust gas turbine a supercharger is known as a turbosupercharger - or more usually simply turbocharger - and common usage is to restrict the use of supercharger to mechanically driven units.

Supercharged Engine:

Types of Supercharger

There are two main types of superchargers defined according to the method of compression: positive displacement and dynamic compressors. The former deliver a fairly constant level of boost regardless of engine speed (RPM), whereas the latter deliver increasing boost with increasing engine speed.

Advantages & Disadvantages of a Larger Supercharger

By Richard Rowe , last updated March 13, 2012 There isn't an engine on the planet that really needs a supercharger. The fact is that these holdovers from the first days of hot-rodding don't do anything that a couple of turbos couldn't do better; they just look, feel and sound cooler while doing it. But before you go cutting a hole in your hood, it might be a good idea to decide on the right size supercharger for your application.

Advantage -- Greater Power Potential

Superchargers are just like engines: all else being equal, a larger-displacement one will produce more power than a smaller-displacement one. And the relationship is fairly linear, too. An 8-71 Roots-type supercharger is capable of flowing twice as much air as a 4-71, and its power potential is roughly double regardless of the engine it's used on. Bear in mind, though, that this relationship does assume that all else is equal. Top Fuel engines typically use 14-71 Roots-type blowers and produce about 10,000 horsepower; far out of proportion to what a street engine with a 6-71 blower would, owing mainly to the fueler's use of nitromethane.

Advantage -- Low RPM Efficiency

A compressor's efficiency map tells you how good the compressor is at compressing air without heating it. The compressor chart looks like a bull's-eye; the vertical plane on the chart is the compressor's boost in pounds per square inch, the horizontal its airflow in cubic feet per minute. The center of the "bull's-eye" is the compressor's peak efficiency. Positive-displacement Roots or Screw-type compressors tend to center the bull's-eye at low boost and low airflow. So, all else being equal, your engine will make more efficient use of its fuel by using a larger compressor and turning it slower.

Advantage -- Octane Tolerance

This is something that few besides professional racers think about, but it is a crucial factor when it comes to keeping your engine alive. This factor is related to the compressor's efficiency map. Hot air reduces your engine's octane tolerance, meaning that you'll end up running closer to your engine's detonation threshold while running the same boost and using the same fuel. This can have a direct affect on power, because it means that you'll have to run less ignition advance and less compression to use the same octane fuel.

Disadvantage -- Parasitic Drag

Parasitic drag is the primary disadvantage to running a larger supercharger, but it is a big one. The supercharger's job is to pump air; the more air you have to pump, the more power you need to pump it. As a frame of reference, the huge 14-71 blower on a Top Fuel engine takes more power just to run at the engine's redline than most super-car engines produce -- somewhere between 500 and 700 horsepower isn't uncommon. The blower's parasitic drag means that you effectively wind up with less power, especially at low rpm when the engine winds up struggling just to turn the blower.

Applications

While a bigger blower has many advantages, in the end you'll need to balance those advantages with the potential parasitic drag involved. In practical terms, this means running the smallest blower you can get away with without overspeeding it just to keep up with engine demand and power goals. If you're looking at a Roots blower, the displacement of the blower is a pretty good guide. The 4-71 blower tends to work best with a four-cylinder. Six cylinders usually work best with a 4-71 to 6-71, and V-8s work best with a 6-71 to 8-71. For a centrifugal blower, multiply your engine displacement by about 1.5 to get a rough naturally aspirated cfm measurement. Then divide your desired boost in psi by 14.7, and multiply that by your NA cfm. This will give you a target boost/cfm range for selecting the supercharger.