The V4 Engine: Design, Pros, and Cons

The V4 engine configuration, a less common but distinct internal combustion engine layout, presents a unique approach to achieving power and compactness. Characterised by its two banks of cylinders set at an angle to form a "V" shape, the V4 engine has carved out a niche in automotive, marine, and industrial applications. While not as ubiquitous as its inline-four counterpart, understanding the V4's engineering principles reveals its specific strengths and weaknesses.

V4 Engine Design Fundamentals

At its core, a V4 engine is an engine with four cylinders arranged in a V configuration. This arrangement typically involves two cylinder banks, each containing two cylinders, angled relative to a central crankshaft. The specific angle between these banks, known as the V-angle, significantly influences the engine's characteristics, particularly its balance and overall dimensions.

Crankshaft and Firing Order

A key aspect of V4 engine design revolves around the crankshaft and how the pistons are connected to it. In many V4 engines, particularly those with a 90-degree V-angle, two opposing cylinders share a single crankpin. This shared crankpin design, while contributing to a shorter crankshaft, can lead to an uneven firing order. An uneven firing order means the combustion events do not occur at perfectly equal intervals, which can result in increased vibration and a less smooth operation. To mitigate this, engines may employ split crankpins, where each cylinder has its own dedicated crankpin. This split crankpin arrangement, often found in engines like the Ford Essex V4 and Ford Taunus V4, allows for an even firing order, resulting in a smoother running engine and potentially requiring a less robust flywheel to manage rotational inertia.

Balance and Vibration

The inherent balance of an engine is crucial for smooth operation and longevity. A V4 engine, especially when configured with a 90-degree V-angle and shared crankpins, can achieve perfect primary balance. Primary balance refers to the cancellation of forces that occur twice per crankshaft revolution. Furthermore, this configuration often offers better secondary balance, which addresses forces that occur four times per crankshaft revolution. This superior secondary balance helps to significantly reduce engine vibration. However, V4 engines with narrower V-angles, such as 60 degrees, may not achieve perfect primary balance without further design considerations. In such cases, similar to V6 engines, a balance shaft is often incorporated to counteract vibrations and ensure a smoother running experience.

Advantages of the V4 Engine

The V4 engine's design offers several distinct advantages that have made it a suitable choice for specific applications:

• Compactness: The most significant advantage of the V4 configuration is its remarkably short length compared to an inline-four engine. This makes it ideal for applications where space is at a premium, allowing for more flexibility in vehicle design and component packaging. The shorter crankshaft also contributes to increased stiffness, making it less susceptible to torsional vibrations and reducing frictional losses due to fewer main bearings.
• Potential for Good Balance: As mentioned, with specific V-angles (like 90 degrees) and crankshaft designs, V4 engines can achieve excellent primary and secondary balance, leading to reduced vibration.

Disadvantages of the V4 Engine

Despite its advantages, the V4 layout also presents several challenges:

• Width: The V-shape inherently makes the V4 engine wider than a comparable inline-four engine. This increased width can complicate the integration of auxiliary systems, intake manifolds, and exhaust systems, especially in tightly packaged engine bays.
• Complexity and Cost: Compared to an inline-four, a V4 engine typically requires two cylinder heads, two separate exhaust manifolds, and two valvetrains (including two sets of camshafts for overhead cam designs). This duplication of components naturally increases manufacturing complexity and cost.
• Uneven Firing (Potentially): Without careful design, particularly the use of split crankpins, V4 engines can suffer from an uneven firing order, leading to increased vibration and a less refined feel.

Historical and Modern Applications

The V4 engine has found its way into a variety of applications over the years:

Automobile Use

In the automotive world, the V4 engine has been employed by several manufacturers. Notably, Ford utilised the V4 engine in models like the Ford Anglia and Ford Corsair in the 1960s and early 1970s. These engines, often the Ford Taunus V4, were known for their compact size and distinctive sound. While not a mainstream automotive engine layout today, its historical presence highlights its viability in specific vehicle designs seeking a compact powertrain.

Motorcycle Use

The V4 configuration is a popular choice in high-performance motorcycles. Brands like Ducati, Honda, and Aprilia have produced iconic V4-powered superbikes and sport-touring machines. The V4's compact nature allows for a desirable chassis design, often contributing to excellent weight distribution and agile handling. The characteristic sound and power delivery of V4 motorcycle engines are also highly appreciated by enthusiasts.

Marine Applications

The V4 engine has also seen significant use in marine applications, particularly in outboard motors. The short engine length of the V4 configuration is a considerable advantage for outboard designs. In 1958, Johnson and Evinrude introduced V4 outboards that quickly proved their worth. Through continuous development, these engines saw substantial power increases over the years, benefiting from manufacturers' racing experience. Yamaha, for instance, introduced powerful two-stroke V4 outboards with advanced oil injection systems.

Other Industrial and Agricultural Uses

Beyond vehicles and boats, the V4 engine has served in industrial, agricultural, and stationary applications. The Wisconsin Motor Manufacturing Company produced V4 petrol engines for these sectors starting in 1935, with their engines being used in various farm equipment. Their largest V4 engine, the VR4D, offered a substantial displacement and torque for its time. Wisconsin continued producing V4 engines until 2019. In the UK, Turner Manufacturing produced diesel-powered V4 engines for industrial and marine use, which were even fitted to tractors like the Turner Yeoman of England. Mitsubishi Heavy Industries also developed the 4ZF, an air-cooled diesel V4 engine used in Japanese military vehicles.

Frequently Asked Questions

When was the V4 engine invented?
While specific invention dates can be complex, the V4 engine layout began to appear in practical applications in the early to mid-20th century. For instance, the Wisconsin Motor Manufacturing Company started producing V4 petrol engines in 1935. Early automotive and motorcycle applications also emerged in the decades following.

What are the main advantages of a V4 engine?
The primary advantages are its compact size, particularly its short length, and the potential for good primary and secondary balance, leading to smoother operation when designed correctly.

What are the disadvantages of a V4 engine?
Common disadvantages include increased width compared to inline-four engines, higher complexity and cost due to duplicated components (like cylinder heads and valvetrains), and the potential for uneven firing if not engineered with split crankpins.

Which cars used V4 engines?
Notable examples include the Ford Anglia, Ford Corsair, and Saab models like the Saab 96 and Saab Sonett. These often featured the Ford Taunus V4 engine.

Are V4 engines common in motorcycles?
Yes, the V4 configuration is quite popular in performance motorcycles from manufacturers like Ducati, Honda, and Aprilia, valued for its compact size and power characteristics.

How does a V4 engine compare to an inline-four engine?
A V4 is shorter but wider than an inline-four. It can offer better balance but is generally more complex and expensive to produce due to having two cylinder heads and valvetrains.

Conclusion

The V4 engine, with its distinctive V-shaped cylinder arrangement, offers a compelling blend of compactness and performance potential. While its increased width and complexity present challenges, its advantages in space-saving and balance have secured its place in various automotive, motorcycle, and marine applications. From the roar of a V4 superbike to the quiet efficiency of a V4 outboard motor, this engine configuration continues to demonstrate its engineering ingenuity.