1.What is the firing order of a four stroke engine?
Its the way the cylinders ignite the air/fuel mixture. The energy that's left turns the crankshaft and is shared with the pistons. The pistons in a Four stroke engine need to have two revolutions to complete the cycle with the firing order in sequence so that there is a equal load on the crankshaft.
2.What is the difference between a S.I and C.I engine?
S.I : the spark from the sparkplug ignites the air/fuel mixture when the cylinder is at TDC.
C.I : Hot air is introduced to the cylinder on the compression stroke and at the top of the stroke fuel will then be introcduced to the hot air. This mixture then expands and ignites.
3.Is there any difference between a S.I and C.I piston if so what?
C.I pistons have a deep groove so that when air is compressed the fuel can be injected with the piston being larger so that it can handle more pressure.
4.What year was the diesel engine invented and by whom?
1897 by Rudolf Diesel
5.What is the purpose of the oil jet on the connectng rod, and where does it spray?
The purpose of the oil jet is to lubricate between the piston and the bore. The oil jet sprays oil onto the cylinder wall.
6.On the connecting rod where is the big end and little end?
Big End : Connects to crankshaft
Little End : Connects to piston
7.What is the purpose of the thrush washers on the crankshaft?
Thrush washers stop unwanted movement. There is a hole on the thrust washer that lines up with the hole on the connecting rod. This is where oil travels throught and sprays the piston and the bore for lubrication.
8.On a diesel engine whats the difference between direct injection and a indirect injection type?
Direct injection: Fuel is simply injected directly to the combustion chamber.
Indirect injection: Fuel goes to the prechamber. The prechamber is linked off the combustion chamber, the combustion chamber starts the prechamber and then the fuel spreads to the combustions chamber.
9.Explan the term valve timming?
The timing of when the valve opens and closes. It is controlled by the camshaft. The timing of the valves is important to be right so that the air/fuel mixture enters the combustion chamber so the exhaust exits.
10.Why do we have valve clearance?
Vakve clearance makes the valves open and close properly, its important that the clearance is correct because if there is too little gap the valve wont close completly and if the gap is to large the valve wont open to fully.
Monday, April 18, 2011
Thursday, April 14, 2011
Engines
What is taper and ovality in the bore, how is it caused how do you check it? The wear of the cylinder bore. caused when the piston moves up and down the cylinder. If it is tapered you can measure the diameter in three places. The top, bottom and middle. When checking the ovality you have to measure the circumference of the bore. The bore will be oval instead of being round.
What is side clearance on a piston and how is it checked? The purpose of the piston ring is to close the gap that is under pressure that makes compression in the cylinder. It is the gap between the piston and the cylinder. Checking the side clearance for the piston: put the piston ring into the piston. Using a feeler gauge put it between the piston and cylinder.
How can you tell the difference between a inlet and exhaust vavle and why? The size of the valves are different. The inlet is larger than the exhaust. The inlet is used for the air/fuel mixture to go to the engine. The exhaust's use is to disguard the left over substances mostly burnt fuel/oil.
What sort of tempatures do the inlet and exhaust valves get upto?
Inlet Maximum: 250 degrees
Exhaust maxumim : 750 Degrees
What temperatures and speeds must the piston be able to cope with?
The handle rotations can reach 7500RPM so the piston needs to be able to hold tempretures up to 300 degrees.
Why do we have piston ring end gap clearance ? The piston ring needs to be able to expand when under heat. The end gap clearance allows this to happen.
What could the result be if the piston ring end gap is too small? The rings could bend or break, close the end gap, cause damage to the bore.
Why do aluminum cylinder heads usually have a steel shim (washer) between the valve spring and the cylinder head surface ? It will bring the tension of the spring up to spec because over time the valve loses tension.
What is meant by the terms S.I and C.I in a four stroke engine?
S.I : stands for Spark Ignition. The spark plug is used to ignite the air/fuel mixture.
C.I : Stands for Compression Ignition. Highly compressed hot air to ignite the fuel, air only is introduced into the combustion chamber at the top of the stroke, then the fuel is injected to the compressed air.
What is the purpose of the margin on the valve? Exhaust valves have a larger margin than the intake valves because they have more heat produced to them. The margins on a valve are to help with the heat because if the valve gets to hot it will burn.
What is the purpose of a core plug? they are used to remove sand from casting when the engine block is cast.
What is end float and run out on a crankshaft, hows is measured?
What is side clearance on a piston and how is it checked? The purpose of the piston ring is to close the gap that is under pressure that makes compression in the cylinder. It is the gap between the piston and the cylinder. Checking the side clearance for the piston: put the piston ring into the piston. Using a feeler gauge put it between the piston and cylinder.
How can you tell the difference between a inlet and exhaust vavle and why? The size of the valves are different. The inlet is larger than the exhaust. The inlet is used for the air/fuel mixture to go to the engine. The exhaust's use is to disguard the left over substances mostly burnt fuel/oil.
What sort of tempatures do the inlet and exhaust valves get upto?
Inlet Maximum: 250 degrees
Exhaust maxumim : 750 Degrees
What temperatures and speeds must the piston be able to cope with?
The handle rotations can reach 7500RPM so the piston needs to be able to hold tempretures up to 300 degrees.
Why do we have piston ring end gap clearance ? The piston ring needs to be able to expand when under heat. The end gap clearance allows this to happen.
What could the result be if the piston ring end gap is too small? The rings could bend or break, close the end gap, cause damage to the bore.
Why do aluminum cylinder heads usually have a steel shim (washer) between the valve spring and the cylinder head surface ? It will bring the tension of the spring up to spec because over time the valve loses tension.
What is meant by the terms S.I and C.I in a four stroke engine?
S.I : stands for Spark Ignition. The spark plug is used to ignite the air/fuel mixture.
C.I : Stands for Compression Ignition. Highly compressed hot air to ignite the fuel, air only is introduced into the combustion chamber at the top of the stroke, then the fuel is injected to the compressed air.
What is the purpose of the margin on the valve? Exhaust valves have a larger margin than the intake valves because they have more heat produced to them. The margins on a valve are to help with the heat because if the valve gets to hot it will burn.
What is the purpose of a core plug? they are used to remove sand from casting when the engine block is cast.
What is end float and run out on a crankshaft, hows is measured?
Sunday, April 10, 2011
How does a four stroke engine work?
How does a four stroke engine work?
the four strokes are:
-Intake
-compression
-power/combustion
-exhaust
Each of these have one full stroke of the piston and a completed cycles is 2 revolutions of the crankshaft.
Head gasket: The head gasket sits between the block and head of the engine. It creates the full compression needed and prevents leaks from either oil or cooland into the cylinders.
Piston: they are attached to the crankshaft by the con rods and create compression of the air/fuel mixture that will ignite then the force from that turns the crankshaft.
Piston rings: these are the open ended rings around the pistion that seal the combustion chamber. they also transfer head from the piston to the cylinders wall and control the oil consumption.
Cambelt: controls the timing of the engines valves.
Flywheel: Keeps the crankshaft tunring from the energy that is made by the power stroke.
What is the bore and the stroke?
- the bore is the diameter of the chamber
- stroke is when the piston moves up and down the combustion chamber from TDC to BDC
the four strokes are:
-Intake
-compression
-power/combustion
-exhaust
Each of these have one full stroke of the piston and a completed cycles is 2 revolutions of the crankshaft.
Name cycles and what the piston is doing and the valves on each stroke.
For Intake the piston moves down getting an intake of a air/fuel mixture the exhaust valve is held shut.
Compression: As the flywheel pushes the piston up the the poppet valve shuts from the pressure of the cylinder. both valves are closed
power/combustion : Spark plug ingites the compressed fuel and when the fuel is burning it drives the piston downwards. both valves are closed.
Exhaust : the piston travels to TDC intake valve is closed and exhaust valve closed/
Who and what year was the four stroke engine invented?
Invented in 1876 by Nikolaus Otto
What is the purpose of the crankshaft?
its the up and down movement of the pistons which converts to a rotational movement of the crankshaft
camshaft: the camshaft is connected to the crankshaft by the timing belt. It controls the inlet, outlet valves and the air/fuel mixture
Valve collets: They work in pairs and hold the exhaust and inlet valves in the engine.
Valve stem seals: It controls the amount of oil that goes to the valves and the combustion chamber for the lubrication.
Head gasket: The head gasket sits between the block and head of the engine. It creates the full compression needed and prevents leaks from either oil or cooland into the cylinders.
Piston: they are attached to the crankshaft by the con rods and create compression of the air/fuel mixture that will ignite then the force from that turns the crankshaft.
Piston rings: these are the open ended rings around the pistion that seal the combustion chamber. they also transfer head from the piston to the cylinders wall and control the oil consumption.
Cambelt: controls the timing of the engines valves.
Flywheel: Keeps the crankshaft tunring from the energy that is made by the power stroke.
What is the bore and the stroke?
- the bore is the diameter of the chamber
- stroke is when the piston moves up and down the combustion chamber from TDC to BDC
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