Pros and cons.
As regards mechanics in the general market, four-cylinder engines have traditionally been the most common. However, since the “downsizing” fever arrived a few years ago and, although today it has eased slightly, now they share the limelight with their little brother, the three-cylinder engine.
Far removed in both cases from engines with a greater number of cylinders, displacement and performance, the truth is that these two types of engines usually share segments and even models, so it is inevitable to make comparisons between them.
So, we are going to analyze what are the advantages offered by a three-cylinder engine over a four-cylinder engine and in which areas that extra cylinder is missing.
How is a three-cylinder engine better?
We’ll start with the obvious: the fact of having one less cylinder makes them smaller engines and also lighter. This makes them suitable for the models with the smallest dimensions on the market, since they can be inserted into smaller holes, and there is also the fact that the reduced weight helps in efficiency tasks.
And that is another of the great advantages of these blocks: they usually have lower consumption and polluting emissions. On the one hand, due to the fact that the mass to be moved is less, and on the other, because the displacement they present is also less.
Of course, it should be clarified that this is something that only happens if reasonable use is made of them, that is, driving them at a normal/low rate, which is what they are designed for. If they are pushed too much, consumption will skyrocket.
Finally, the fact of having one less cylinder also means that, obviously, there are fewer parts involved in the engine, which in the long run means that there are fewer components that are susceptible to failure. This, added to less maintenance, makes them more economical at the cost level.
In addition, it is also worth mentioning that, a priori, since the engine weighs less and has a lower mass, in the event of an accident it is less likely that it will enter the interior of the passenger compartment.
How is a three-cylinder engine worse?
Taking into account the advantages they have over four-cylinder engines, it is also easy to figure out what are the points in which they are weak compared to these: the elimination of that fourth cylinder is something that is noticeable above all in everything related to performance and the behavior.
The three-cylinder blocks usually have a very small displacement, as a general rule of 1 liter and, although in some cases, such as the Toyota GR Yaris, high powers are reached, as a general rule they deliver much fairer horsepower. This makes them have a greater reaction capacity, especially at low revs, which is why they mount a turbo.
This is why, mainly, they are mounted on small, urban, utility and, at most, compact cars; where even with moderate power they can offer correct performance, although mainly only in urban areas.
Another disadvantage is that, with three cylinders, they are engines that are more unbalanced than one with four, which means that they generally have much more vibrations, which in some cases is even uncomfortable inside the passenger compartment.
In addition, this also leads to the fact that they are usually noisier, especially when the mechanics are required, because when the throttle is pressed hard the engine goes as far as it can, but in general it is more “overwhelmed” than a four-cylinder, so it noise in these conditions is even higher.
