HOW A TURBOCHARGER WORKS
A significant difference between a turbocharged diesel engine and a traditional
naturally aspirated gasoline engine is the air entering a diesel engine is compressed
before the fuel is injected. This is where the turbo charger
is critical to the power output and efficiency
of the diesel engine.
It is the job of the turbo charger to compress more air flowing into the engine’s
cylinder. When air is compressed the oxygen molecules are packed closer together. This
increase in air means that more fuel can be added for the same size naturally aspirated
engine. This then generates increased mechanical power and overall efficiency
improvement of the combustion process. Therefore, the engine size can be reduced for a
turbocharged engine leading to better packaging, weight saving benefits and overall
improved fuel economy.
How Does a Turbocharger Work?
A turbo charger is made up of two main sections: the turbine and the compressor. The
turbine consists of the turbine wheel (1) and the turbine housing (2). It is the job of
the turbine housing to guide the exhaust gas (3) into the turbine wheel. The energy from
the exhaust gas turns the turbine wheel, and the gas then exits the turbine housing
through an exhaust outlet area (4).
The compressor also consists of two parts: the compressor wheel (5) and the
compressor housing (6). The compressor’s mode of action is opposite that of the
turbine. The compressor wheel is attached to the turbine by a forged steel shaft (7),
and as the turbine turns the compressor wheel, the high-velocity spinning draws in air
and compresses it. The compressor housing then converts the high-velocity, low-pressure
air stream into a high-pressure, low-velocity air stream through a process called
diffusion. The compressed air (8) is pushed into the engine, allowing the engine to burn
more fuel to produce more power.
Better Fuel Efficiency Through a Better Oil Pump
As the market and government regulations push automakers to improve emissions and
fuel consumption, they are evaluating all opportunities in the engine system to reduce
losses. The oil pump
important component that consumes engine power as it protects engine components from
frictional wear and overheating by delivering oil at the correct pressures.
Fixed-displacement oil pumps currently circulate oil in most automobiles. Designers
typically oversize the pumps to handle the harshest engine operating conditions. Most of
the time, they consume more power and deliver significantly higher oil pressure than
needed. They contain pressure-relief valves as a crude, cost-effective, and reliable way
to avoid excessively high oil pressures. But these designs are inefficient, losing
significant amounts of energy at high oil flows typical in internal-combustion engines.
Providing Customized Oil Flow
Variable-displacement oil pumps help to minimize energy losses. Their active control
matches the oil flow and pressure the engine needs, eliminating excess oil flow,
significantly reducing the parasitic load on the engine crankshaft, and ultimately
In variable displacement pumps, changing the displacement volume controls the flow
rate. Vane-pump designs have hydraulic and electrical controls and actuators that move
the pump housing and vary the eccentricity of the rotor. Electronic control signals and
solenoid control valves vary the pressure set points as operating conditions dictate.
Automobile OEMs adopted these types of pumps in 2011, applying them in engines for
high-end vehicles in Europe. Although research has evaluated the fuel-economy benefits
of reduced oil flow from a torque-reduction perspective, the industry lacked information
about its control, use, and thermal interactions with other engine systems.
As part of an industry- and university-consortium project partially funded by the UK
Technology Strategy Board, researchers at the University of Bath, Bath, UK, and Ford
Motor Company, Detroit, MI, thermally tested variable-displacement oil pumps to gain
insight about performance and oil pumping speed. The group evaluated vane and rotor pump
designs in an active 2.4-L diesel engine on an engine stand at many different operating
conditions and found that fuel economy benefits warrant the pump expense.
Understanding Oil Coolers
When engine output rises beyond a certain threshold per liter of displacement, an oil cooler
important, critical even. There is a lot to the selection and installation of an oil
cooler, so to find out more, we caught up with Zac Beals, a technical sales
representative with Setrab USA, a Swedish company that specializes in a full range of
heat exchangers and radiators for OEM applications, and oil cooling for motorsport.
There are right and wrong ways to add an oil-cooling system, based on application and a
number of other factors, but there are two key tenets to follow when adding an oil-
cooling system: get expert help and don’t skimp on materials.
“Oil is the only thing preventing metal-to-metal contact, and any high-performance
engine is designed with its own optimal oil temperature range based on how much work the
oil is doing in that system,” Beals said. “The demands on the oil in a high-revving
turbocharged four-cylinder are different from the demands on the oil in a naturally-
aspirated V-8, and the differences only get more specific from there.
“What we do know for sure is that most generally, temperatures in excess of a
normal operating range will break down the ability of the oil to do its traditional
lubrication job,” Beals added. “A rule of thumb is that every 20 degrees in excess
heat will half the life of the oil. This has a related effect on every internal
component the oil touches.”
An oil-cooling system consists of the fittings and hoses to get the oil out of the
engine to the cooler itself and back into the engine. It seems pretty simple, right? Not
Belt driven fan clutches have been used as standard equipment on many vehicles for
decades. However, the automotive clutch market is diminishing as other more efficient
options are hitting the market and being demanded by consumers. Fan Clutches are ‘fluid
’ coupling devices that provide air flow through the radiator by using the water pump
shaft to power the fan blade. When the pump is cool or at normal operating temperature,
the fan clutch
partially disengage. However, due to only partially disengaging they will always be
spinning at about 30% of the water pump speed at all times. When compared to an electric
fan, fan clutches are quite inefficient.
In simple terms, the cylinder head
is just a casting that tops off the engine block, holds the
valves and forms the combustion chambers. Working in combination with the camshaft(s),
induction and exhaust systems, the head determines how the engine breathes, the engine’
s power curve and personality. The “right” cylinder head will deliver peak power in
the preferred rpm range, providing good throttle response and producing the kind of
torque and horsepower numbers your customers demand.
Using the wrong head can ruin your reputation.
Some people pick a set of cylinder heads based on previous experience,
reputation or simply brand recognition. Some look for highest airflow claims while
others take the price path. The best selection process, of course, is rarely so simple.
The core of the engine is the cylinder, with the piston moving up and down inside
the cylinder. Single cylinder engines are typical of most lawn mowers, but usually cars
have more than one cylinder (four, six and eight cylinders are common). In a multi-
cylinder engine, the cylinders usually are arranged in one of three ways: inline, V or
flat (also known as horizontally opposed or boxer), as shown in the figures to the left.
So that inline four we mentioned at the beginning is an engine with four cylinders
arranged in a line. Different configurations have different advantages and disadvantages
in terms of smoothness, manufacturing cost and shape characteristics. These advantages
and disadvantages make them more suitable for certain vehicles.
Let's look at some key engine parts
in more detail.
The spark plug supplies the spark that ignites the air/fuel mixture so that
combustion can occur. The spark must happen at just the right moment for things to work
The intake and exhaust valves open at the proper time to let in air and fuel and to
let out exhaust. Note that both valves are closed during compression and combustion so
that the combustion chamber is sealed.
A piston is a cylindrical piece of metal that moves up and down inside the cylinder.
Piston rings provide a sliding seal between the outer edge of the piston and the
inner edge of the cylinder.
What Is A Brake Booster And What Does It Do?
The brake booster
used to amplify the force applied on the
brake pedal when transferring that force to the brake master cylinder. Brake systems
that have them are often called “power brakes.”
The brake booster is used on almost all cars with hydraulic brakes — you won’t see
them on vehicles that use pressurized air systems as their primary brake circuits.
BRAKE ROTORS/BRAKE DISCS
What they are: Sometimes called brake rotors, sometimes called discs, this brake
part is one of the main components of disc brakes. When brake pads press against the
disc/rotor on each side, it causes the system to slow down or stop.
How long they last: As with all brake
, it can vary, but brake rotors/discs tend to last anywhere from 30,000 to
70,000 miles. You can also extend their life with brake resurfacing. They should be
inspected every 12,000 miles, however.
When to replace: The surface is where this brake part wears down. Over time, grooves
or ridges can develop where the brake pads press down on them. If the brake pads
can't maintain an even contact surface, you may experience grinding, meaning
it's time to resurface or replace the rotors or discs. It's recommended to
replace brake rotors/discs in pairs.
Excessive Steering Play / Loose Steering
If your steering rack
and pinion wear out, the steering will feel loose. You will also notice that the
car wanders at high speed, and it is hard to keep it in the lane.
Also, every road imperfection causes your car to easily move left to the right
instead of staying in a straight line.
You may also notice that steering is harder at lower speeds. On top of all these
symptoms, you will also notice that the wheels don't return to a straight position