IC Engine Question -- Starting sequence for 4-stroke engine

In summary, the conversation discusses the process of starting an IC engine and how it is initiated by a kickstart. The expert highlights the different strokes involved in the process and explains how the engine may not start on the first compression stroke, but rather after a few turns of the crankshaft. They also mention a real-life example of how multiple starters are used to ensure that a diesel-powered machine starts within a specific time frame.
  • #1
Swap123
Hi , Everyone…

one very general question regarding ic engine is

suppose our vehical (Ic engine) Is at rest ,and we are ready to start vehical , when we kicked the kick By our legs then there is compression stroke..,right?,
then when air fuel mixture is sucked in cylinder ( When there is suction stroke initialy)?
 
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  • #2
The four strokes are in order, intake, compression, power, exhaust. A four stroke IC will not start without at least one intake stroke.
 
  • #3
A kickstart turns the engine over a few times.
 
  • #4
You mean to say
when we kicked

1)st there is suction ,then
2) Compression
initially
how?
 
  • #5
xxChrisxx said:
A kickstart turns the engine over a few times.
Not universally so. When I was a kid I got an exotic Italian bike from a kid too small to survive the kickback when it caught on the initial kick in the compression stroke. It didn't even turn once, less than a quarter of a turn. When the MG would pop it would toss him onto the roof of an adjacent automobile.
 
  • #6
Doug Huffman said:
Not universally so. When I was a kid I got an exotic Italian bike from a kid too small to survive the kickback when it caught on the initial kick in the compression stroke. It didn't even turn once, less than a quarter of a turn. When the MG would pop it would toss him onto the roof of an adjacent automobile.
Sounds like something from a cartoon.
 
  • #7
Doug Huffman said:
When I was a kid I got an exotic Italian bike...

Perchance... a Ducati ?

When the MG would pop...

MG ?... A magneto?... with or without an impulse coupling ?... I've hand propped a J-3 Cub, many a time... too many... lol
 
  • #8
Firing on the very first compression is fairly rare, and certainly should not be considered as typical.

The more common situation is that the initial kick (or starter engagement) starts the crank shaft turning. At some point, sooner or later, at the top of a compression stroke, the engine fires. If enough energy is imparted to the system (chemical burn energy plus remaining kinetic energy from the initial kick), then the engine starts and you are off to the races.

How many times the engine has to turn before it fires is different in just about every situation, depending on mixture temperature, engine oil temperature (affects oil viscosity), and a host of other variable.

Many years ago, I worked on standby diesel power systems for nuclear power plants. These are intended to supply emergency power to the core cooling pumps if primary power is lost. It is absolutely essential that these standby units start when required. The machines my employer built were powered by diesel locomotive engines. They were equipped with six starters on the flywheel, working in pairs. Four of these were compressed air starters, working in pairs. When the signal to start was received, the first pair would attempt to start the engine. If after about 2 seconds the engine had not fired, the first starter pair were disabled and the second pair attempted to start. If that failed also, the first pair were energized again to attempt a start, and if that failed, then the second pair would try again. If all that failed to start the engine, the third pair were energized. These were different. The had an explosive charge serving as a high pressure gas generator, and thus were a one-shot only, last ditch resort. The expectation was that, within 15 seconds after the initial signal to start, the engine would be started, the speed stabilized at running speed (900 rpm), the field applied to the generator, the speed stabilized again, and the load motors on the pumps would be started. That was a very demanding spec to meet!
 
  • #9
OldEngr63 said:
The machines my employer built were powered by diesel locomotive engines.

ALCOs... by any chance ?

Maybe similar to... this ?
 
  • #10
I know that we used ALCo engines on a few other machines, but I am not aware of any ALCos going into nuclear standby service. Most of the nuke jobs used EMD 645 engines, either 16 or 20 cylinders and 180 hp/cylinder. One really big machines had two 20 cylinder EMDs, one on each end of the generator shaft. It was a LONG machines (two 20 cylinder engines with a large generator in between). The ground shook when that machine cranked!
 
  • #11
OldEngr63 said:
The ground shook when that machine cranked!

:oldsmile:
 

Related to IC Engine Question -- Starting sequence for 4-stroke engine

1. What is the purpose of the starting sequence for a 4-stroke engine?

The starting sequence for a 4-stroke engine is designed to initiate the combustion process and get the engine running smoothly. It involves a series of steps that prepare the fuel-air mixture, ignite it, and ensure that the engine is receiving enough fuel and air to sustain combustion.

2. What are the steps involved in the starting sequence for a 4-stroke engine?

The starting sequence typically involves four steps: intake, compression, power, and exhaust. During the intake stroke, a mixture of air and fuel is drawn into the combustion chamber. In the compression stroke, the mixture is compressed to increase its pressure and temperature. The power stroke is when the spark plug ignites the mixture, creating a controlled explosion that produces the power to move the piston. Finally, in the exhaust stroke, the burned gases are expelled from the cylinder.

3. How does the starting sequence differ between a 4-stroke engine and a 2-stroke engine?

The main difference between the starting sequence for a 4-stroke engine and a 2-stroke engine is the number of strokes required to complete a full cycle. In a 4-stroke engine, the intake, compression, power, and exhaust strokes are completed in four separate strokes of the piston, whereas in a 2-stroke engine, these strokes are completed in just two strokes of the piston.

4. Are there any variations in the starting sequence for different types of 4-stroke engines?

Yes, there can be variations in the starting sequence for different types of 4-stroke engines, depending on their design and purpose. For example, diesel engines have a slightly different starting sequence due to their use of compression ignition, while rotary engines have a unique starting sequence due to their rotary design.

5. What are some common issues that can occur during the starting sequence for a 4-stroke engine?

Some common issues that can occur during the starting sequence include a weak or faulty spark, a clogged fuel filter, or a malfunctioning carburetor. These issues can result in difficulties starting the engine or rough idling. It is important to regularly maintain and troubleshoot these components to ensure smooth operation of the engine.

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