answersLogoWhite
Auto Parts and Repairs
Mechanical Engineering
Combustion Engines

Difference between SI Engines CI Engines?


Top Answer
User Avatar
Wiki User
Answered 2010-07-25 19:09:31

SI is SPARK IGNITION - Otto (4-stroke) and Day (2-stroke) cycle

CI is COMPRESSION IGNITION (DIESEL) also in 4- and 2-stroke variants

The SI spark plug is timed to start combustion at the ideal moment, usually some degrees before the piston reaches the top (TDC or Top Dead Centre). The burning mixture then drives the piston down for the power stroke.

The CI fuel is injected (sprayed) into the cylinder at the ideal moment - this too is usually some degrees before TDC, and the red-hot air in there then starts the fuel burning. This then drives the piston down for the power stroke.

SI is limited in maximum compression ratio (the amount the air or mixture is compressed as the piston rises in the cylinder), or it can start to behave like CI (Dieselling).

CI uses the highest compression ratio possible to improve ignition - and - improve efficiency too... The expansion ratio is the inverse of the compression ratio, and the more that the burning gas is allowed to expand whilst doing work, the better the efficiency.

CI is also an 'excess air' cycle, potentially. A full cylinder of air is compressed each time, and the amount of fuel injected is varied to change power - this is beyond the lean burn that can be achieved with SI.

567
๐Ÿ™
0
๐Ÿคจ
0
๐Ÿ˜ฎ
0
๐Ÿ˜‚
0
User Avatar

Your Answer

Still Have Questions?

Related Questions

Why si engines are quantity governed engines and ci engines are quality govrned?

All engine are whether CI or SI are quantity governed. what is quality governed?? You have discovered it or wht??


Why for the same power CI engines are larger and heavier than SI engines?

for ci engines it requires large cylinder becoz ci itself means compression ignition engine, where as si engine(spark ignition) engine requires small cylinder so, the ci engine is heavier than the si engine.


What is the difference between a SI engine and a CI engine?

An SI engine ignites the fuel with a spark (SI = Spark Ignition) whereas the CI engine ignites the fuel with heat generated from compression (CI = compression ignition)


Why CI engines are used in trucks and other heavy vehicles but not why SI engine?

Compression ignition (CI) engines use diesel is as the fuel, while spark ignition (SI) engines use petrol. SI engines are lightweight and achieve high speeds while diesel CI engines although heavier and slower engines, are more robust and have a higher thermal efficiency. Their robust build (and fewer parts) makes diesel CI engines ideal for heavy machinery.


What is SI engine and CI engine?

An SI engine is a spark ignition engine. A CI engine is a compression ignition engine. SI engines use spark plugs to ignite fuel in the combustion chamber. CI engines use compression in the combustion chamber to ignite the fuel.


What will happen if SI engines is used in place of CI engines in trucks?

we can use si engines in place of ci engine in trucks.. Bt as u know in trucks heavy power is required to carry such high loads.. Nd also the cost of petrol is higher than diesel so to obtain high mechanical power nd less running cost diesel engines are used..!


Where is fuel and air mixed in an engine on a newer car?

Mixing of fuel and air depends on type of the engine whether SI or CI. In carburetted versions of SI engines the charge mixes in the carburetion chamber and the mixture is let into the engine. There are direct injection SI engines(GDI) where the injection takes places at various stages of charge compression stroke. In CI engines the fuel is mixed with air in the combustion chamber itself. It is to be borne in mind that these mixing phenomenon are the same be it a new or old car.


What is the difference between the Honda Civic DX engine and the Honda Civic Si engine?

The difference between the two engines is a Honda civic dx stock engine is 1.6L single overhead cam nonvetch motor and the Honda civi si stock engine is a 1.6L doul overhead cam vetch motor. I'm not positive about the exact number but the difference is about 70 horse power between the dx and si motors


What are si and ci engines?

SI engine means Spark Ignition Engine where combustion products(air,fuel)are ignited in combustion chamber by means of spark from spark plug which is located on cylinder head..CI engine means Compression Ignition Engine,here combustion is take place by means of compression..


What are stages of combustion in CI engines?

Intake, compression, power/combustion, exhaust. Same as a standard SI (Spark Ignition) CI (Combustion Ignition) is how diesel operates. They contain no spark plugs. The compression heats the fuel to the point of SELF COMBUSTION .


Why can a CI engine be more easily pressure charged compared to SI engines without fear of detonation?

because it only compresses/pressurized air (without the mixture of fuel)


What is the difference between Si and SI?

SI is Sulphur and Iodine, Si is Silicon. Tehy are both different elements on the peridoic table


Difference between Honda civic SE and SI?

...the difference is in the second letter... ;)


Whats the difference between a Honda si and an lx?

hatchback


The difference between the Metric System and SI?

the SI (systeme internationale) uses the metric system for measurements


Working principle of a four stroke engine?

Are we talking about the CI or the SI version, as they both operate differently. CI version


What is CI unit of speed?

If you mean "SI", that would be meters/second.


What was the difference between watt and horsepower?

watt is the si unit of power


What is the difference between the metric system and SI units?

There is no difference they are the same thingAnswerSI is the current version of the metric system.For example, the centimetre, the calorie, and the litre are examples of metric units, but they are not SI units.


What is the difference between SI units and the customary system?

The difference is the tranguillary measurements of the two said units


What is the difference between volt and ampere?

Volt is the SI unit for pootential difference 1V = 1J/1C Ampere is the SI unit for current 1A = 1C/1sec.


What are the difference between Ge and Si diode?

GE diode is made up of germanium and Si diode is made up of silicon and there is a difference in break down voltages also for Ge it is 0.7v and for Si it is 0.3


What is the Difference between Si and Ge diodes?

The significant operational difference between a Si diode and a Ge diode is that Si diodes have a knee voltage of 0.7V needed to allow current flow and Ge diodes have an operational voltage of 0.3V to allow current flow.


What are the difference between si and ge diode?

the energy required to break covalent bond in si is 1.1ev and in ge is 0.7ev


What are the types of combustion chambers in SI engines?

swirl


Still have questions?