The V8 engine is also known as the Eight-Cylinder engine. These Eight-cylinder engines have the cylinder setting either of V-type or vertical straight. The V8 is the engine that represents American motoring, but it is loved all around the world.
The V8 engine gets their name from having a cylinder block in the shape of a “V” and it is having eight cylinders.
In the V8 engine, the eight-cylinder is setting in two sets of 4 cylinders in lines making the V. In this Two cylinders operate from a single crank because it allows faster acceleration and more efficient exhaust system designs.
The angle is V is 90°. When piston N0.1 on the left is at T.D.C. the piston No.1 on the right is completing half of its downward stroke.
Although the primary inertia forces are balancing in V-8 engines, the secondary forces are out of balance and tend to induce a horizontal vibration which generally requires the use of a friction damper on neutralizing it.
Different V-8 manufacturers number their cylinder differently and thus firing order numbering systems are different. This engine operates under the same basic principles as any other gasoline four-stroke engine.
How Each Cylinder Works
Let’s focus on how one cylinder works.
- First, the piston draws in air and fuel, as it moves downward.
- Then it compresses that air and fuel. As the piston moves upwards.
- Next, a spark plug sparks ignite the air-fuel mixture and forcing the piston downward.
- Finally, the piston pushes out the exhaust gasses on its way back up before the cycle repeats itself.
Now in the V8 engine, this cycle is happening in eight different cylinders at different times. With this 8 cylinders firing for every 90 degrees of the crankshaft revolving. It means that at any point in time there are two cylinders on the power stroke.
Methods of Numbering Cylinders in V8 Engines
The fig shows three methods of numbering cylinders in V-8 engines. The arrangement as at A is using in Motorcars, in which the firing order is
1 – 8 – 4 – 3 – 6 – 5 – 7 – 2
The Oldsmobile has the firing order,
1 – 8 – 7 – 3 – 6 – 5 – 4 – 2
The cylinder arrangement as at (B) is using in Ford, Mercedes and Lincoln with a corresponding firing order of,
1 – 5 – 4 – 8 – 6 – 3 – 7 – 2
1 – 5 – 4 – 2 – 6 – 3 – 7 – 8
The cylinder arrangement as at (c) is using in Buick engine with a firing order of,
1 – 2 – 7 – 8 – 4 – 5 – 6 – 3
In the straight type arrangement, the eight-cylinder is arranging vertically in line, using a crankshaft with the throws set at 90° from each other.
Four crank throws are in the horizontal plane and four in the vertical plane, forming a cross in the side view.
The power impulse is at every 90° movement of the crankshaft. The firing order in American straight engines is,
1 – 6 – 2 – 5 – 8 – 3 – 7 – 4
Other orders of firing may be,
1- 7 – 3 -8 – 4 – 6 – 2 – 5
1 – 5 – 2 – 6 – 4 – 8 – 3 – 7
The straight-8 engines are more compact in width than V-8 engines. They are balancing for both primary and secondary inertia forces.
Advantages of ‘V’ type engines over inline engines:
Although inline 8 cylinder engines were once widely used in automobiles, they have been replaced by V8 engines due to having some advantages:
V8 engine permits a shorter, lighter and more rigid engine. The more rigid engine allows higher running speeds and higher combustion pressure with less difficulty from flexing or bending of the cylinder block and crankshaft. Flexing forces the engine out of line increases frictional losses and wear, and it may also set up internal vibrations.
The shorter engine permits more space for a passenger on the small wheelbase. The lighter engine provides the vehicle to be light.
It permits the use of intake manifold that assures relatively even distribution of the air-fuel mixture to all cylinders since all cylinders are relatively close together.
It permits lowering of the hood line and thus a lower car profile. This is due to the carburetor and other parts are rested between the two rows of cylinders so they do not take up headroom above the cylinders.
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