Indian automobile manufacturers these days are increasingly focusing on making cars with 3 cylinder engines. There is a very rampant misconception among the people that 3 cylinder engines are inferior to 4 cylinder engines. Hence it is strongly believed that they are only suited for entry-level budget cars. However, the reality is the stark opposite. 3 cylinder engines have different functionality in comparison to 4 cylinder engines but are in no ways outright inferior. Ford uses a 3 cylinder engine on the Ecosport which is in no ways an entry-level car. So here, we will bust some myths and take a look at the differences between a 3 cylinder engine and a 4 cylinder engine. We will also list the intricate pros and cons of each.
Also Read: The Working of the Engine Explained
As strongly obvious as it is, the main difference between a 3 and a 4 cylinder engine is the number of cylinders. But that’s not all. Because of the number of cylinders, a 3-cylinder has a very different firing order to maintain balance. In the case of a 4 cylinder engine, power is generated every 90-degree rotation of the crankshaft. In a 3 cylinder, however, power is generated every 120 degrees. Due to such variations, a 3 cylinder engine shows drastically different characteristics in comparison to a 4 cylinder engine.
This is perhaps the most sought after plus point of a 3 cylinder engine. The Having one cylinder less, the total material required to manufacture a 3 cylinder engine is lesser. This has a two-fold advantage to the manufacturers. Firstly, the lesser material is to be used so that saves them a significant amount of investment per engine. Next, since there is one cylinder less, you can create a smaller sized engine for the same displacement. This allows the manufacturers to make a compact engine bay and focus on making the interiors roomier.
This is the most sought after plus point from the perspective of a consumer. A 3 cylinder engine is much more fuel efficient compared to a 4 cylinder engine of the same size. This is because of two primary factors, reduced frictional losses and lighter weight. Since there is one cylinder less, the frictional losses caused by metal surfaces coming in contact within the engine block is lesser. This basically translates to more force production for lesser fuel. Adding to that, due to the absence of one cylinder, the engine block is much lighter. Even the crankshaft constructed to hold the pistons is lighter. Basically, there is a good amount of overall weight savings. Both of these factors combined give 3 cylinder engines an upper hand in terms of fuel efficiency.
In general, a 3 cylinder engine is cheaper to maintain and run. With one cylinder less, the total parts functioning in the engine are lesser. This means there are a lesser number of parts being used in the engine. So, the automatically incurs lesser wear and tear compared to a 4 cylinder engine. Even, If they do die off, the total expense to change/ fix the parts will be less directly as a virtue of the number of parts being lesser.
Now let’s take a look at the positive aspects of a 4 cylinder engine.
The most advantageous aspect of a 4 cylinder engine is that it is extremely refined. All engines these days are 4-stroke engines (intake, compression, power, exhaust). With a 4 cylinder engine, the overall balancing is perfect. Through every stroke made in a 4 cylinder engine, one cylinder is always in the power stroke and the rest are all at different positions than each other. This gives the crankshaft a much more streamlined motion which translates to smooth engine operation on the whole. The 4 cylinder engine generates power every 90-degree rotation of the crankshaft. The 3 cylinder engine, on the other hand, makes power every 120 degrees. To achieve this orientation, the crankshaft has to be made in a way which causes an approximate firing delay of 1/3rd of a cycle. This gap is seen in real time as rougher idling and noisier engine operation.
As we discussed in the previous point, 3 cylinder engines have an area of no firing in the cycle. During this period, the crankshaft is rotating purely on the momentum generated by the piston in the previous stroke. So at lower RPM’s a 3 cylinder engine really struggles to put out the power. But as the revs increase, the crankshaft gets ample conserved momentum and it is able to put a healthy power output. The 4 cylinder engine on the other hand, does not suffer from this problem as it has no lag in the firing order. It works equally good at lower RPMs as it does at higher RPMs.
So which engine is better? 3 cylinder engines nowadays are packed with almost equal amounts of power as 4 cylinder engines of the same capacity. So which one stands triumphant here? The answer is, none. Each type of engine has it’s plus points and negatives and both suit different purposes. A 3-cylinder engine is better suited for fuel efficiency and cost savings. A 4 cylinder engine is better suited for refinement and punchy power delivery. All in all, it boils down to where your preferences lie.