How to install a turbocharger in four easy steps

Turbo Installation Instruction

Pre-Installation

• Service air cleaners and eliminate all restrictions and leaks.
• Inspect and remove all foreign material from air inlet and exhaust manifold before installing.
• Replace all oil pressure and drain lines which could be kinked, broken or internally damaged.
• Change engine oil and oil filters.
• Replace all contaminated crankcase and compressor filters.

Pre-Lubrication

• Do not start engine before attaching new oil drain line to turbocharger, crank engine until oil flows from oil drain hole in bearing housing.
• Attach new oil drain line to turbocharger.

Installation

• Mount turbocharger and exhaust manifold using new gasket and avoid usingsealing material.
• Inspect exhaust system; remove any restrictions which might cause excessive back pressure before connecting to turbocharger.
• Attach new oil inlet line to turbocharger.
• Align bearing housing drain hole to not more than 30 deg. From verticalcenter position.
• Tighten clamps, cap screws or nuts to recommended specifications.
• Connect air pipage system to turbocharger.

Operation

• Idle engine for 5 minute.
• Check all systems for oil, air or exhaust leaks.
• Always have operated idle engine for 1 minute prior to shutdown for longer turbocharger life.

Turbo blow off valves

Turbo charged engines operating at wide open throttle and high rpm require a large volume of air to flow between the turbo and the inlet of the engine. When the throttle is closed compressed air will flow to the throttle valve without an exit (i.e. the air has nowhere to go).
This causes a surge which can raise the pressure of the air to a level which can be destructive to the engine e.g. damage may occur to the throttle plate, induction pipes may burst. The surge will also decompress back across the turbo as this is the only path that the air can take. This sudden flow of air will often cause turbulence and a subsequent whistling noise as the air passes past the compressor wheel.

The reverse flow back across the turbo acts on the compressor wheel and causes the turbine shaft to reduce in speed quicker than it would naturally. When the throttle is opened again, the turbo will have to make up for lost momentum and will take longer to achieve the required speed, as turbo speed is proportional to boost/volume flow. (This is known as Turbo Lag) In order to prevent this from happening, a valve is fitted between the turbo and inlet which vents off the excess air pressure. These are known as an anti-surge, bypass, blow-off or dump valve. They are normally operated by engine vacuum.

The primary use of this valve is to prevent damage to the engine by a surge of compressed air and to maintain the turbo spinning at a high speed. The air is usually recycled back into the turbo inlet but can also be vented to the atmosphere. Recycling back into the turbo causes the venting sound to be reduced and can actually help keep the turbo spooled while changing gears. The benefits of venting to the atmosphere are simply the ease of installation (because there is no need to run an extra hose to plumb the charge back into the system) and that it makes a sound considered desirable by some. There are no/little performance benefits for venting to the atmosphere, but because a Dump Valve is present the Turbo will slow down naturally rather than forcefully and will shorten the time needed to "spool-up" to counteract any turbo lag.

Working principle

A turbocharger consists of a turbine and a compressor linked by a shared axle. The turbine inlet receives exhaust gases from the engine exhaust manifold causing the turbine wheel to rotate. This rotation drives the compressor, compressing ambient air and delivering it to the air intake manifold of the engine at higher pressure, resulting in a greater amount of the air and fuel entering the cylinder.
The objective of a turbocharger is the same as a normal supercharger; to improve upon the size-to-output efficiency of an engine by solving one of its cardinal limitations. A naturally aspirated automobile engine uses only the downward stroke of a piston to create an area of low pressure in order to draw air into the cylinder through the inlet valves. Because the pressure in the cylinder cannot go below 0 psi (vacuum), and because of the relatively constant pressure of the atmosphere (about 15 psi), there ultimately will be a limit to the pressure difference across the inlet valves and thus the amount of airflow entering the combustion chamber. This ability to fill the cylinder with air is its volumetric efficiency. Because the turbocharger increases the pressure at the point where air is entering the cylinder, and the amount of air brought into the cylinder is largely a function of time and pressure difference, more air will be forced in as the inlet manifold pressure increases. The additional air makes it possible to add more fuel, increasing the power and torque output of the engine, particularly at high engine rotation speeds.
Because the pressure in the cylinder must not go too high to avoid pre-ignition and physical damage, the intake pressure must be controlled and this is done by a wastegate, which controls boost by routing some of the exhaust flow away from the exhaust side turbine. This controls shaft speed and regulates boost pressure in the inlet tract.

The application of a compressor to increase pressure at the point of cylinder air intake is often referred to as forced induction. Centrifugal superchargers operate in the same fashion as a turbo; however, the energy to spin the compressor is taken from the rotating output energy of the engine's crankshaft as opposed to exhaust gas. Superchargers and turbochargers use output energy from an engine to achieve a net gain, which must be provided from some of the engine's total output. In the case of superchargers, either directly or from a separate smaller engine, perhaps electrically driven from the main engine's generator.

Turbo Wastegate

By spinning at a relatively high speed the compressor turbine draws in a large volume of air and forces it into the engine. As the turbocharger's output flow volume exceeds the engine's volumetric flow, air pressure in the intake system begins to build, often called boost. The speed at which the assembly spins is proportional to the pressure of the compressed air and total mass of air flow being moved. Since a turbo can spin to RPMs far beyond what is needed, or of what it is safely capable of, the speed must be controlled. A wastegate is the most common mechanical speed control system, and is often further augmented by an electronic boost controller. The main function of a wastegate is to allow some of the exhaust to bypass the turbine when the set intake pressure is achieved. Most passenger cars have wastegates that are integral to the turbocharger.