Having never owned a supercharged car before, and not knowing much at all about them, can someone point me to a good primer to learn all there is to know about how superchargers work?

The supercharger essentially draws mass quantities air into the engine combustion chamber, correct?

I've read in the "detailing 101" threads that some MCS owners run forced water into the Supercharger (among other liquids!) to clean it--surely you can't just flood the supercharger with water from a hose WHILE THE SC is still attached to the engine--can you???

Do you have to remove it from the engine before doing this for a thorough cleaning? If the SC forces air directly into the engine combustion chamber, then what keeps stuff like rain water from ingesting into the engine through the same route as the air?

Also, any other very basic stuff a new owner of an MCS should know, having to do specifically with the supercharger? I'm sure keeping it free of debris (leaves and bugs and whatnot) is essential but anything else to keep it running tip-top shape? What is this I hear about an "oil catch can"? Is that a component of the supercharger as well?

Thanks a lot for your input.

-boognish

 

Supercharger Basics

A supercharger is any device that pressurizes the air intake to above atmospheric pressure. Both superchargers and turbochargers do this. In fact, the term "turbocharger" is a shortened version of "turbo-supercharger," its official name. [FONT=arial,helvetica] [/FONT][FONT=arial,helvetica]
[SIZE=-2]Photo courtesy HowStuffWorks Shopper[/SIZE]
[SIZE=-1]A twin-screw supercharger[/SIZE][/FONT]
The difference between the two devices is their source of energy. Turbochargers are powered by the mass-flow of exhaust gases driving a turbine. Superchargers are powered mechanically by belt- or chain-drive from the engine's crankshaft.
An ordinary four-stroke engine dedicates one stroke to the process of air intake. There are three steps in this process:

1. The piston moves down.
2. This creates a vacuum.
3. Air at atmospheric pressure is sucked into the combustion chamber.

Once air is drawn into the engine, it must be combined with fuel to form the charge -- a packet of potential energy that can be turned into useful kinetic energy through a chemical reaction known as combustion. The spark plug initiates this chemical reaction by igniting the charge. As the fuel undergoes oxidation, a great deal of energy is released. The force of this explosion, concentrated above the cylinder head, drives the piston down and creates a reciprocating motion that is eventually transferred to the wheels.

[SIZE=-1]A basic engine with the addition of a supercharger.[/SIZE] Getting more fuel into the charge would make for a more powerful explosion. But you can't simply pump more fuel into the engine because an exact amount of oxygen is required to burn a given amount of fuel. This chemically correct mixture -- 14 parts air to one part fuel -- is essential for an engine to operate efficiently. The bottom line: To put in more fuel, you have to put in more air.
That's the job of the supercharger. Superchargers increase intake by compressing air above atmospheric pressure, without creating a vacuum. This forces more air into the engine, providing a "boost." With the additional air in the boost, more fuel can be added to the charge, and the power of the engine is increased. Supercharging adds an average of 46 percent more horsepower and 31 percent more torque. In high-altitude situations, where engine performance deteriorates because the air has low density and pressure, a supercharger delivers higher-pressure air to the engine so it can operate optimally.
In the next section, we'll take a closer look at how superchargers work.
How It Works

Unlike turbochargers, which use the exhaust gases created by combustion to power the compressor, superchargers draw their power directly from the crankshaft. Most are driven by an accessory belt, which wraps around a pulley that is connected to a drive gear. The drive gear, in turn, rotates the compressor gear. The rotor of the compressor can come in various designs, but its job is to draw air in, squeeze the air into a smaller space and discharge it into the intake manifold. [FONT=arial,helvetica]
[SIZE=-2]Photo courtesy Muscle Mustang[/SIZE]
[SIZE=-1]ProCharger D1SC centrifugal supercharger[/SIZE]
[/FONT]
To pressurize the air, a supercharger must spin rapidly -- more rapidly than the engine itself. Making the drive gear larger than the compressor gear causes the compressor to spin faster. Superchargers can spin at speeds as high as 50,000 to 65,000 rotations per minute (RPM).
A compressor spinning at 50,000 RPM translates to a boost of about six to nine pounds per square inch (psi). That's six to nine additional psi over the atmospheric pressure at a particular elevation. Atmospheric pressure at sea level is 14.7 psi, so a typical boost from a supercharger places about 50 percent more air into the engine.


As the air is compressed, it gets hotter, which means that it loses its density and can not expand as much during the explosion. This means that it can't create as much power when it's ignited by the spark plug. For a supercharger to work at peak efficiency, the compressed air exiting the discharge unit must be cooled before it enters the intake manifold. The intercooler is responsible for this cooling process. Intercoolers come in two basic designs: air-to-air intercoolers and air-to-water intercoolers. Both work just like a radiator, with cooler air or water sent through a system of pipes or tubes. As the hot air exiting the supercharger encounters the cooler pipes, it also cools down. The reduction in air temperature increases the density of the air, which makes for a denser charge entering the combustion chamber.




Heres the origonal link http://auto.howstuffworks.com/supercharger2.htm

 

Oh, and to clean the intercooler, you must remove it from the car. It is not possible to clean it while on the car.

...Well the inside.

 

Thanks qwertmonkey, that's great information.

So the MSC is an air-to-air supercharger, yes? Meaning it is air-cooled, not connected to a separate water source (radiator) for cooling?

Is it easy to remove for cleaning...I see just 4 bolts on top. Is it equally easy to put back on (sometimes things are easy to remove, and a bear to replace!)

rock on,

-MB

 

Well, not quite. The intercooler (which is the radiator-like thing that is mounted on top of everything) is an air-to-air implementation. If you are into modding your car, you can get a water-to-air intercooler.

The intercooler is relatively strightforward to remove and replace. Supercharger removal is another matter.

Out of curiousity, why are you wanting to clean the intercooler and/or supercharger?

 

Intercoolers get an oil buildup on the inside which can decrease the effiency. So some people will clean their intercoolers from time to time. Or you can install an oil catch can which will help keep the oil from accumiliating int he intercooler.

 

Where is the reference that someone washed the inside of their supercharger? I really doubt that.

Also, a supercharger is parasitic meaning it takes HP from the engine to drive it. The intercooler merely helps keep the air temp down since the colder the air, the more dense it is.

An oil catch can (OCC) help trap oil that "might" accumulate in the IC. MINI didn't provide one so chances are you dont need it. Some ppl like them to gain the last "ounce" of performance. While it might collect some oil, its very doubtful (IMHO) that you will ever feel the effect in terms of power loss.

 

Boognish, a big for doing your homework and studying your car. Keep working on it and all this stuff will start to be second nature.

 

I completely agree. Unless you have a heavily modded engine, it is doubtful that you will experience a performance degradation from any residual oil fumes that might make their way to the intercooler. And, if you do experience a performance degradation, it will come after a significant number of miles have been run.

 

it's not in the detailing forum, but i read this thread yesterday, so i knew what he was referencing...
https://www.northamericanmotoring.co...an+intercooler

 

Yucca is talking about, I believe, taking the IC cover off and cleaning the inside of the IC (get any oil residue out). That not the supercharger.

 

sorry for the dumb question. is the intercooler the black square thing that sits on top of the engine?

 

did some quick googling... i think this might help....
intercooler

but how it cools on top of the engine is beyond me... is there airflow there?

 

If what you are referring to looks like a radiator (cooling fin matrix), then yes, that is the intercooler. Your reference to black color could be the cover/trim piece to the intercooler. If you go to webbmotorsports.com, or any of the other performance vendors that advertise on NAM, you will see an example of the intercoolers they sell.

 

There are two basic types of ICs, Top mounted (TMIC) and Front Mounted (FMIC). FMIC will be obvious because its looks like a radiator and clearly air flows through it. MINIs is top mounted. Air flows through the air intake across the IC. The black is just a trim piece.

 

Just for the record...

As the air leaves the supercharger, it's compressed making it very hot. This air flows into the left side of the intercooler. The intercooler uses outside air (coming in from the hood scoop) to cool the compressed air back down ideally to the outside temp. This air flows out the bottom of the intercooler into the engine compartment, and eventually out of the car. The intercooler allows a higher density to be put into the engine. From the right side of the intercooler, air flows into the cylinders.

That's my best explanation without going into a Thermodynamic analysis of the system

 

They probably placed the MINI Intercooler on the top of the engine for packaging reasons. I believe in 99.99% of all cases (and I'm talking out my butt here so feel free to correct me)...anyway, in the vast majority of cases a similarly sized FMIC will outperform the TMIC. The TMIC has to deal with all that heat under the bonnet! You could always do like one of the classic Mini owners in the UK did and just mount the IC on *top* of the bonnet. Looks goofy as hell, but the car was sure fast!

 

I would think that the TMIC approach was selected due to cost reasons - less costly to do a short airpath routing with a TMIC.