Twin Spark Tech

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By:Shivu R Reddy


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For making the combustion of fuel as fast as possible can be

done by using two spark plugs which spark alternatively at a certain time

interval so as increase the diameter of the flame & burn the fuel

instantaneously. The technology used is known as Twin Spark Technology.

This report gives the basics fundamentals of twin spark

ignition engine and working of 4 stroke twin spark ignition engine.

It also gives the recent developments like Digital twin sparktechnology, DTS-i, DTS-Si, EFI and DTS-Fi technologies used in modern

two wheelers.


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Twin spark technology was used first time in Alfa Romeo

grand prix car in 1914 to enable it to achieve a higher power

output from its engines.

And in the early and middle 1980s, Alfa Romeo incorporated

this technology into their road cars.

A conventional 4 Stroke engine has a Single Spark Plug

whereas two spark Plugs are used in this technology.


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The Twin Spark name comes from the fact that there are two

spark plugs per cylinder.

The two sparks on the Twin Spark engines do not fire at exactly

the same time.

Less ignition advance, as there are 2 symmetrically placed

sparks plugs are used

Also, leaner mixtures can also be tolerated for better fuel

economy.


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Suction stroke

During suction stroke, the pistonmoves downwards by the crankshaft

movement.

The inlet valve is open and

exhaust valve is closed during thisstroke.

The downward movement of

piston sucks the fresh air fuel mixture

in the cylinder from the carburetorthrough open inlet valve.

At the end of suction stroke the

inlet valve closes.


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Compression stroke

During this stroke, the piston movesupward, thus compressing the charge.

Ignition and much of compression also

takes place during this stroke.

The mixture under compression is

ignited by spark produced by two

sparkplugs.

The first sparkplug sparks and after twomicroseconds the second sparkplug

sparks.

The inlet valve and exhaust valve

remains closed during compression

stroke.


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Power stroke

The expansion of gases due to heat ofcombustion exerts pressure on cylinder

and piston.

Under this impulse the piston moves

downward thus doing the useful work.

Pressure and temperature decrease

during expansion.

Both valves remain closed during this

stroke.


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Exhaust stroke

During this stroke, the inlet valve isclosed and exhaust valve opens.

The greater part of burnt gases escapes

because of their own expansion.

The piston moves upwards and pushes

remaining gases out of open exhaust

valve.

The exhaust valve closes at the end of

the exhaust stroke and some residual

gases remain in the cylinder.


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DTS-iDTS-i stands forDigital Twin Sparkignition.

DTS-Si

The DTS-Si stands forDigital Twin Spark-Swirl ignition.

EFI

The EFI stands forElectronic Fuel Injection.

DTS- Fi

The DTS- Fi stands forDigital Twin Spark- Fuel

injection


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Spark plug & valve Combustion Process


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TWIN SPARK SI ENGINE SINGLE SPARK SI ENGINE

Burning of Air fuel mixture is

fast and complete

Burning of Air fuel mixture is slow

and incomplete

Two Spark plugs are used ineach cylinder

Single Spark plug are used in eachcylinder

Rate of combustion is fast Rate of combustion is slow and

insufficient

Complete combustion of air

fuel mixture and gives max

power

Incomplete combustion of air fuel

mixture and less power developed is

less as compared twin spark engine

Reduction of travel of flame,

thus decreases knocking

Since the flame travels long distance

more chances of knocking

Lower hydrocarbon Emission Higher hydrocarbon Emission


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Uniform power delivery in all operating conditions.

Long service life.

Lower emission rate.

Better fuel efficiency

High specific power.

Increased volumetric efficiency.

Better starting of engine in winter and cold starting conditions

because of increased compression ratio.

Decreases knocking due to better combustion.

More effective combustion in low load and at idling speed. Sparkplug tip temperature is reduced which in turn reduces pre-

ignition.

Life of vehicle increases.


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Carbon or soot in sparkplug.

Maintenance cost of sparkplug is increased.

Better design of cylinder head is needed foraccommodation of two sparkplugs.

Cost of engine is increased.

Only overhead combustion chamber need to beused.


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Twin spark engines are implemented in ALFA ROMEO cars of version ALFA ROMEO GT

ALFA ROMEO 145

ALPA ROMEO 146

DTS-i and DTS-Si are Bajaj Auto exclusive technologies in India.

DTS-i was first introduced in the Pulsar 150/180/200 models in 2003.

The DTS-Si technology came in the XCD 125 in 2007 and currently also

available on Platina 125 and XCD 135.

The DTS- Fi technology was introduced in the pulsar 220 models. Bajaj

displayed the 220 DTS-Fi in 2006.


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Twin spark ignition engine has more advantages from

single spark ignition engine.

Emissions and knocking of engines are one of the majordrawbacks of automobile engines. These factors are reduced by

using twin spark engines.

Hence Twin spark ignition engines should be used widelyin automobiles which in turn increase the performance of the

vehicle.


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Twin Spark Tech