What do the technical specifications of your Cherokee’s engine mean?

What do the technical specifications of your Cherokee’s engine mean?

Even though all engines are very similar when you look at them, there are many different types. We will now show you what the most usual technical specifications that you can find in the technical datasheet of your Cherokee mean.

  1. Gasoline or Diesel engines

    This is the main difference between engines. Engines that need Diesel have incandescent spark plugs that only work when the car starts. Once the engine is running, the fuel ignites by itself since it is compressed inside the cylinders thanks to the high temperature it reaches.
    On the other hand, gasoline engines work thanks to the spark constantly created by the spark plugs. This means that they work all the time the engine is running.
    Another difference between these two engines is that Diesel engines are generally heavier, and their structure is more robust.
  2. Number of cylinders

    It is the number of cylinders inside the engine. The engine power is generated in the cylinders because that is where the pistons are. For this reason, the more cylinders the engine has, the more its power will be. This also means that the engine will be bigger and heavier. It is also important to notice that if there are a lot of cylinders, the engine will consume more fuel.
  3. Bore/stroke ratio

    These are the piston’s measurements, and they can be expressed in centimeters or inches. They indicate the cylinder diameter (bore) and the longitudinal displacement (stroke) that the piston does inside the cylinder when the engine is running. These measurements allow us to measure the “displaced volume” by the piston. If the diameter is wide and the piston has a short stroke, the engine will be fit for sports cars. In other words, the revolutions per minute (RPMs) will be high.
  4. Engine displacement

    It is the total available volume in the engine cylinders. It is calculated by multiplying the stroke length, the bore, and the number of cylinders.
    Depending on the country, it may be expressed in liters (1.6 L, 2.0 L, 3.6 L), or in cubic inches (98, 110, 250, 510 CI).
    Generally, the higher the engine displacement is, the more power your car will have, but the higher its fuel consumption will be.
  5. Cylinder arrangement

    a) In-line arrangement: nowadays, it is hard to find engines with more than 6 in-line cylinders because they take up too much space under the hood.

    b) V-type arrangement: They are more compact and create fewer vibrations, but they can only be used with an even number of cylinders (V6, V8, V10, etc.).

    c) Opposed arrangement: they are flat and not frequently used because their manufacture and maintenance are very demanding. Moreover, like the V-type arrangement, they can only be used with an even number of cylinders.
  6. Valvetrain type: SOHC and DOHC

    a) SOHC (single overhead camshaft): It only has one camshaft placed in the cylinder head. Only one camshaft controls all the engine’s valves. They generally have more power if there are low RPMs. The camshaft is in charge of opening and closing the engine’s valves.
    b) DOHC (double overhead camshaft): It has two camshafts placed in the cylinder head. One camshaft controls the admission valve while the other controls the escape valve. The performance of these engines is usually better if the RPMs are high. Moreover, its parts are usually lighter and can move faster.
  7. Compression ratio

    It is the measurement of how much the volume of the air-fuel mixture can be compressed inside of the cylinder. The higher this number is, the higher the engine power will be. For example, if there is an 8:1 ratio, this means that the mixture will be reduced to one octave of its original volume.
    Generally, compression ratios are between 8:1 and 12:1 for gasoline engines.
  8. Naturally aspirated or turbo engines

    A naturally aspired engine means that the engine draws air directly through an air intake. In turbocharged cars, on the other hand, the turbocharger injects air by forcing it into the engine. The advantage of using turbochargers is that, in small engines, the power increases because it is possible to inject more air and fuel into the cylinders.
  9. Torque

    It is the “strength” that the engine has when it accelerates.
    It is measured in “foot-pounds” or in “N.m” (1 N.m = 0.737 ft.lb), and to express it, the RPM of the engine must also be stated. For example: 150 N.m @ 1700 RPM.
    Off-road cars usually have a lot of torque and not so much power. This enables them to drive up big slopes at a slow speed or dodge big pits and rocks. Diesel engines have more torque than gasoline engines.
  10. Power

    It is the car’s ability to accelerate (to react) at high speeds.
    It is measured in HP (Horse Power), or in KW (1 HP = 0.745 KW).
  11. Revolutions per minute (RPM)

    They represent the engine speed. It is important to distinguish them from the car speed since they are not the same thing. Both are related by the transmission. For example, if the car is in neutral gear and we press the accelerator, we may only change the engine speed but not the car speed.
    Technically speaking: Torque x RPM = Power
    In a car, the RPM are controlled by the accelerator. Their rise depends on how much we press the accelerator, and this will be reflected in the tachometer. The higher the RPMs are, the noisier the engine will be.
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