What is Inline Engine? – Working, Types and Applications

The engine is a vital part of the vehicle. Engines have changed dramatically in recent years, with new innovations appearing almost every year. However, the basic design of the engine is almost the same. There are multiple types of engines, and an inline engine is one of them. The inline engine is also known as a straight engine. This article mainly explains the various aspects of an inline engine.

What is an Inline Engine?

An inline engine is a very simple and traditional engine design. In the inline engine, the cylinders are oriented installed in a single straight row. Therefore, it is also known as a straight engine, or I engine.

inline engine

The term “inline engine” is usually used for aircraft engines. In vehicles, the term “inline engine” uses to represent the straight engine (engines with a single row of cylinders). However, in aircraft, the term “inline” may also use to represent the engines that don’t have straight configurations such as horizontally opposed, W, or V engines.

These types of engines contain the multiple number of cylinders, such as two, three, four, five, six, or eight cylinders. However, the maximum engine manufacturer refers to an inline four-cylinder engine as an inline 4 engine. These engines are denoted by L4 or I4.

The inline engine is the most common engine type in vehicles with a displacement of up to 3.0 l. These engines have simple design and operation. They have a small size and require a very low area for installation.

Therefore, they have easy manufacturing. They have less cost than a ‘V’ engine or horizontal engine. With this design, the engine’s camshaft is typically mounted to the cylinder block in a tappet and pushrod arrangement. The manufacturer places the engine valve inside the block or cylinder head next to the piston.

The main advantage of the inline engines is that they are more balanced than the V engine due to their even weight distribution. However, the V engines produce more torque than the inline engines at a lower speed.

Read More: Types and Use of V Engines

Inline Engine Configurations

The inline or I engine has the following configurations:

1) Inline or Straight

This engine has a single row of cylinders placed at a specific angle but is usually upright or upside down.

2) V

An engine that has 2 rows of cylinders angled less than 180 degrees between them and typically drives a common crankshaft that is inverted or upright.

3) Horizontal or O

This engine has two cylinder rows angled at 180 degrees. All of these cylinders drive a common crankshaft installed almost universally as a horizontal cylinder’s rows for aircraft or a vertically mounted crankshaft for helicopters.

4) W

Three rows of engines drive a common crankshaft, with the first and last rows spaced 180° apart or less.

5) X

A multi-row engine with four rows around a common crankshaft, typically evenly spaced.

6) Fan

For engines with more than three rows, the angle between the first and last rows is 180° or less, similar to the W engine.

7) U

An engine that powers two sets of cylinders side by side and drives separate crankshafts connected to a single output.

8) H

An engine with four sets of cylinders drives two crankshafts connected to an output. Actually, two opposing engines are combined and mounted horizontally or vertically.

9) Opposed piston

Two-stroke engines (typically diesel/compression ignition engines) have a single bank of cylinders driving two crankshafts, with the pistons moving toward each other to form a single combustion chamber.

Inline Engine Vs V Engine

The cylinders of an inline engine are arranged in a single row, while the cylinders of the V engine are arranged in two rows.

The inline engine cylinders extend vertically up from the crankcase and are aligned with the main bearing of the crankshaft. However, the V-type engine has two rows of cylinders, usually crating 60 degrees or 90 degrees radius between the two rows.

The manufacturers place their engines inline to achieve maximum efficiency and affordability. According to a mechanical point of view, the I engine has low manufacturing cost, simple design, and high efficiency.

In contrast, V engine manufactures if you have a low installation area and want high power. Due to the arrangement method, a V-shaped engine has the ability to pack maximum pistons into less space, have higher displacement, and generate more torque at a slow speed.

The I engines are more balanced than V-engines due to their even weight distribution. It’s also easy to play with as it usually only has a cylinder head and exhaust manifold.

One more advantage of inline engines is that they can easily handle odd-numbered pistons, which a V-shaped configuration cannot do. The odd number of cylinders in a V engine can vibrate if the number of cylinders at both ends is not evenly balanced for trade, and the electricity supply is also not uniform. It’s almost impossible to make it smooth because it’s expected.

V-set pistons share the same crank or crankshaft via connecting rods. These motors require less space than parallel motors of the same power. V engines with the same number of cylinders are usually half the size.

Because the power stroke comes from both sides of the crankshaft, the V engine produces more torque at lower revs.

An inline engine is easier to build than a V engine.

Advantages and Disadvantages of Inline Engine

Advantages of Inline Engine

  1. These engines have easy construction.
  2. They have easy construction than V engines
  3. The inline engines have an easy operation.
  4. They have low cost than the V engines.
  5. They have small in size.
  6. They have a compact design.
  7. It has lightweight.
  8. It has just one cylinder head and one exhaust manifold.
  9. It less moving parts than a V engine. This means that it reduces less energy than a V engine.
  10. They require very low manufacturing and maintenance costs.
  11. These engines are more balanced than V-engines due to their even weight distribution.

Disadvantage of Inline Engine

  • They have a high center of gravity than some other types, such as H4.
  • They are not much rigid as V6 and V8 engines.
  • The inline engine has cooling and overheating issues.
  • It requires a large nose which generates issues related to bumper-to-bumper traffic.

Applications of Inline Engine

  1. These engines are most commonly used in aircrafts and planes.
  2. The straight engines are used in motorcycles.

FAQ Section

Why is it called an inline engine?

It is known as an inline engine because all the cylinders of this engine are arranged in a single straight row.

What are the configurations of Inline Engines?

The inline engines have the following configurations:

  • Inline or Straight
  • V
  • Horizontal
  • W
  • X
  • Fan
  • U
  • H
  • Opposed piston

What are the parts of the Inline Engine?

The inline engine has the following major parts:

  1. Cylinders
  2. Piston
  3. Housing
  4. Camshaft
  5. Crankshaft
  6. Connecting rod
Read More
  1. Different types of Engines
  2. Types of Wankel Engines
  3. Types of IC Engines
  4. Working of Stirling Engine
  5. Difference between 2-stroke engine and 4-stroke engine
  6. Types and working of Petrol Engine
  7. Working of Diesel Engine

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