1. 1、How a Turbo System Works

Turbos provide enhanced fuel economy and performance. A turbo is a basic "air pump" that pushes a volume of air into the engine, which increases the power output. This turbo is driven by a turbine in the exhaust system, connected by a direct shaft to an impeller in the intake system. The more exhaust that flows, the more air is pumped into the engine. In most automotive and some other applications, a wastegate is provided which opens as intake system pressure is raised to a preset level by the turbo.
Engine power is proportional to the amount of air and fuel that can get into the cylinders. All things being equal, larger engines flow more air and as such will produce more power. If we want our small engine to perform like a big engine, or simply make our bigger engine produce more power, our ultimate objective is to draw more air into the cylinder. By installing a turbocharger, the power and performance of an engine can be dramatically increased.

So how does a turbocharger get more air into the engine? Let us first look at the schematic below:

	1 Compressor Inlet 2 Compressor Discharge 3 Charge air cooler (CAC) 4 Intake Valve 5 Exhaust Valve 6 Turbine Inlet 7 Turbine Discharge

The components that make up a typical turbocharger system are:

• The air filter (not shown) through which ambient air passes before entering the compressor (1)
• The air is then compressed which raises the air’s density (mass / unit volume) (2)
• Many turbocharged engines have a charge air cooler (3) that cools the compressed air to further increase its density and to increase resistance to detonation
• After passing through the intake manifold (4), the air enters the engine’s cylinders, which contain a fixed volume. Since the air is at elevated density, each cylinder can draw in an increased mass flow rate of air. Higher air mass flow rate allows a higher fuel flow rate (with similar air/fuel ratio). Combusting more fuel results in more power being produced for a given size or displacement
• After the fuel is burned in the cylinder it is exhausted during the cylinder’s exhaust stroke in to the exhaust manifold (5)
• The high temperature gas then continues on to the turbine (6). The turbine creates backpressure on the engine which means engine exhaust pressure is higher than atmospheric pressure
• A pressure and temperature drop occurs (expansion) across the turbine (7), which harnesses the exhaust gas’ energy to provide the power necessary to drive the compressor

 2、What are the components of a turbocharger?

The layout of the turbocharger in a given application is critical to a properly performing system. Intake and exhaust plumbing is often driven primarily by packaging constraints. We will explore exhaust manifolds in more detail in subsequent tutorials; however, it is important to understand the need for a compressor bypass valve (commonly referred to as a Blow-Off valve) on the intake tract and a Wastegates for the exhaust flow.

1. 3、How to fit a turbo

A/Ascertain why the old unit failed.
To avoid the same problem to recur and damage the new unit. You can find help in our trouble shooting.
B/Ensure you are replacing like-for-like. The part number should be shown on the old turboon dataplate. If you have difficulty reading the part number, LMturbo is the effective turbo export that can help you find the right unit from the Vehicle Identification Number.
C/Check for cleanliness.
The smallest particles of dirt can do irrevocable damage to a turbocharger so check the engine intake/exhaust and aftercooler systems for cleanliness and obstructions, carefully removing oil, pieces of gasket, dust, dirt and other debris. Replace the air filter.
D/Check that the oil inlet and oil drain flanges are clean and free from obstruction
internal carbon and sludge, removing them to clean if necessary. If in doubt, replace with new.
E/Replace the oil and filter
including the prime filter, ensuring that only qualified recommended parts and specified oil are used. Check the exhaust mounting flange is flat and free from cracks and carbon debris, and the studs are in good condition.
F/Check that the manifold casting is not cracked on the outside or breaking up internally.If in doubt, replace with new.
G/ Mount the turbocharger on the exhaust flange
checking that the turbine inlet gasket fits correctly to give a gas tight seal.
H/ Align the end housings with all other connections and ensure that all fastenings are tightened to the specified torque. Check that any rings are not trapped when orientating the compressor cover as this may lead to a leakage.
I/Connect the oil drain pipe, using the gaskets supplied. Do not use any liquid gasket product on turbocharger connections. Sino Turbocharger supplies a gasket set with every turbocharger.
J/Fill the turbocharger oil feed hole with clean engine oil and rotate the rotor by hand.
K/Connect all external fittings to the turbocharger. On older engines, pull out the fuel stop and crank on the starter to develop oil pressure. On modern engines, start and idle for two minutes, checking that the oil warning light has gone out and that all air, gas, and oil connections are tight and free from leakage, using soapy water to help detect gas leaks. Tighten any fastenings as appropriate.
4、Why do turbochargers need to be balanced ?
All high speed machinery needs to be balanced to fine limits. In the case of the turbocharger this has traditionally been achieved by careful balancing of individual components which normally ensures an adequate level of balance for heavy duty applications, typically large diesels.
The advent of the passenger car turbocharger has brought with it a more demanding requirement because of the higher rotational speeds and the more exacting demands of the installations. The typical car engine is light in construction and hence susceptible to vibration sources, which cause noise, and the vehicle driver will not tolerate even modest noise levels.
For these reasons the car turbocharger requires balancing to much finer limits and this cannot be achieved by balancing of individual components alone. Assembly tolerance stack-up means that even carefully balanced components, when assembled in a group, can give a cumulative imbalance which is unacceptable, while geometric errors in shaft straightness, squareness of faces etc., can also considerably influence the total assembly. This problem is exaggerated when parts are re-used in reconditioned units, and modern high-speed turbochargers are particularly sensitive.
The solution to this problem is to achieve a more precise state of balance which can only be attained by balancing the complete assembly over a speed range close to the maximum operating speed of the unit.
If this balancing process is not carried out, the result can be a turbo which will be noisy in operation and will suffer failure prematurely. 
THE HIGH SPEED BALANCING PROCESS

 KEY       
_____As the turbo is tested after assembly. Peak vibration 4.4 g-pk
_____ After balancing, peak vibration is reduced to under 1.0 g-pk

(Results from a typical Garrett GT15 on balancing machine)