The Engine has always been an area of great misconstruction. As such, knowing more about engine models and designs is essential. Not only does it help with your general knowledge, but it also gives you a clear picture of what you are getting when you want to buy a car.
V8 is a common phrase in the automotive industry, no surprise you have heard it and even used it. Pull up a chair and hone in as we breakdown and make plain everything about this Engine.
No doubt next time you walk into a dealership, you'll be in the know when they start throwing around engine-related terms.
The Basics of the V8 Engine
The engine size is usually determined by the number of cylinders an engine packs. It is apparent why the V8 Engine is called so: it has eight cylinders.
These eight cylinders are arranged in two banks (4 cylinders in each) set at an angle: usually, 90° to resemble a V shape hence the designation of the letter V in the engine name. However, some V8 engines take other angles such as 45°, 60°, and 72°.
The eight pistons drive the same crankshaft. The piston numbering alternates between the banks. It starts on the low end. If the low piston in the right bank is 1, the piston in the left bank at the same low position will be 2. The second-lowest on the right bank will be three and so forth till the 8th.
For a V8 90° Engine, a piston will be fired at every 90° crankshaft rotation. The V8 can be pictured as two straight-four engines sharing a crankshaft. This engine configuration results in the smooth running of the vehicle.
History of the V8 Engine
The first V8 Engine was built in 1902 by a French engineer & inventor Léon Levavasseur. He patented his work and named the gasoline injected engine 'Antoinette'. This Engine was used in aircraft and speedboats then. He continued working and making improvements on the engine model.
Enjoying approval, the Engine began making its way into cars. By 1904 Renault and other automobile manufacturers had introduced race cars using the V8 Engine. The next few years saw other cars and aero-engine manufacturers build and use the V8 Engine to power their vehicles.
First was Darracq in 1905 (in a bid to break the world speed record), then Rolls Royce in 1906. However, Rolls Royce went back to inline-six design. A year later, Hewitt Motor company installed a V8 engine to their touring car.
The company (Hewitt Motor) believed that the 8-cylinder V Motor they had manufactured was better and lighter than the 6-cylinder. The 8-cylinder Motor had all the best features from the six cylinders and took less space. It made use of a four-throw crankshaft and was fed from a carburettor.
Complications in starting large engines hindered mass production of the V8 Engine. However, the development of electric starters overcame this challenge.
Henry Ford came up with the one-piece Engine by 1932 which was the breakthrough for mass production of the Engine.
Angle Designs
The 90° engine design has banks displaced at a right angle. V8 engines of this kind are wide. Most V6 engines are built from this model by cutting off the two cylinders resulting in a 90° V6 Engine. These engines, however, are prone to vibrations.
Balance shafts having eccentric weights are used to reduce these vibrations. They have a rotation opposite to that of the crankshaft.
Despite the 90° V8 engine being the most common configuration, there are other configurations. They include the 72° V8 engine that has featured in racing and the 60° Rolls Royce Meteorite Engine. Lancia also developed a shorter and narrower V8 engine that had a cylinder bank angle of 14°.
Crankshaft Designs
The crankshaft of a 90° V8 engine can be made in two forms:
- Single-plane (flat-plane)
- Two-plane (cross-plane)
1. Flat-plane
The single-plane crankshaft, also known as the flat plane was the most common used crankshaft during the early days of V8 engine development. This is because designing the cross-plane crankshaft was troublesome.
The crankpins in this design are at a straight-line angle (180°). During operation of the Engine, two pistons are moved together. The result is secondary vibration that is half as frequent as cross-plane. The vibration is, however, twice as energetic.
Counterweights are not used for this design because it has plane balance. Flat plane V8 engines are not common in road cars. Some manufacturers have still come up with flat-plane V8s for road cars. They include Ford, TVR, Ferrari, Lotus, and McLaren.
For racing cars, however, the flat plane design is perfect. Cosworth's Double Four Valve is perhaps the most notable Engine that was built with this design.
2. Cross-plane
This configuration derives its name from the appearance. The first & last crankpins, as well as the second & third crankpins, are at 180° to each other. The pairs are perpendicular to each other. Viewed from the end, the crankshaft appears to form a cross.
Because of the plane imbalance posed, counterweights are used to counter the vibrations. Cross-plane produces secondary vibration twice as frequent to those of a flat-plane. Additionally, the vibration is half as strong as a flat plane.
Larger displacements can be achieved using the cross-planes without undesired vibration due to the secondary vibration vantage. Note that the inclusion of the counterweights in this engine design reduces the speed up and slow down rate.
The cross-plane design is a complex one and hence wasn't initially used. Even after its proposal in 1915 at an auto engineering conference, it took eight years before its production began.
Working
Each of the V8 cylinders has four strokes Intake, Compression, Power and Exhaust in that order. After every 180° rotations, two cylinders are fired.
Each cylinder has a piston moving up and down to mix up air and the fuel. Combustion of the mixture created by a spark produces a downward push on the cylinder. As a result, motion is developed, which propels the vehicle.
To balance the V8 Engine, weights are added onto the crankshaft. These weights adjust the rocking vibrations caused by the piston movement.
Advantages of the V8 Engine
The V8 engine has several upsides that make it preferred to other engine configurations.
- It is short and easier to fit in engine compartments compared to inline engines
- It has a higher displacement (above 3.0L) hence more powerful
- Has minimal vibrations thus provides smooth running.
- Provides better acceleration
Disadvantages of the V8 Engine
Despite the advantages the V8 offers, it has drawbacks too. They include
- Complex than the inline-six engines and thus make repair challenging
- The 90° big-bore V8 engine is generally limited to rear-wheel-drive vehicles and a few trucks due to its wide and long dimensions.
Applications
Large automobiles have engines that make use of the cross-plane configuration.
V8 engines are mostly found in powerful automobiles with the common types being sports cars, pick-up trucks, and SUVs. Muscle cars to use this Engine
Race cars have specially configured V8 engines to fit their power and speed requirements. They make use of the flat-plane design for faster acceleration. Also, the design has an efficient exhaust set-up.
The V8 has also been applied in other areas such as aviation & motorcycle (during the early days) and marine (small engines though).
The choice of Engine you prefer depends on what you are after performance or efficiency. The V8 offers you more power, but it is at a cost.
Author - Sam O