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Knowing your Car: Piston, U-Bolt, Air Duct

A vehicle is composed of easily over a thousand parts, and familiarizing the majority of these parts will add more to your knowledge of car parts. Hopefully, you’ll know what part to change when something goes wrong. For this session of “Knowing your Car”, we’ll dive in more with the piston,U-Bolt and air duct.



As one of the many moving parts inside your engine, the piston is connected to the crankshaft via the connecting rod, which prevents the cylinder bore to wobble. Note that the piston rings located at the side eliminates the possibility of engine oil leaking into the combustion chamber.

The piston is responsible for sucking in the air, compressing the air-fuel mix and pushing the waste gases out of the cylinder. Notably, a different piston is used when the engine is either (a) naturally aspirated or (b) using a power adder i.e. turbo, supercharger and/or nitrous oxide.  The durability of the piston is dependent on how much power you push your engine to produce.

Unburned fuel can deposit on the piston and cylinder, which can accumulate over time. So every time you overhaul your engine, make sure you clean the soot and dirt that can diminish the performance of your engine.



Primarily found in leaf springs, U-Bolts are used to clamp tubing, steel bars and strips together. There are four elements of a U-Bolt that you should take in account every time you replace them: material, thread dimensions, inside diameter and inside height.

  1. The material determines the strength of the U-Bolt depending on the maximum load it is designed to support. The harder the steel, the heavier loads it can support.
  1. The thread dimension refers to the length of the thread and determines the size of the nut to be used.
  1. The inside diameter refers to the width of the bolt, or more specifically, the distance between the two threaded ends of the bolt. This determines the “allowable width” that you can clamp.
  1. The inside height refers to the length of the U-Bolt and it determines how much you can stack together to clamp them.

Air Duct

Air Duct

Also known as the air intake, the air duct is the passage of air that leads to the engine. It is mainly comprised of the following: an air filter, the mass flow sensor and the throttle body.

  1. The air filter, as the name suggests, filters the impurities in air like dust and dirt particles that can affect your engine in bigger ways you can imagine. More often than not, there are replacement filters for the specific model of your car that you can just drop in and drive away.
  1. Attached to the duct is the mass flow sensor that measures the volume of air flowing into the engine. The engine control unit then calculates how much fuel is needed for combustion so that a balance of power and fuel economy is attained.
  1. Containing the valve that allows air into the cylinders when you press the gas pedal, the throttle body is either mechanically linked to the pedal itself or controlled by electronics. It opens completely when you press the pedal to the metal.

These are the basic components of an air intake, particularly for fuel-injected engines found in most modern vehicles. For carburetted engines in older vehicles, the mass flow sensor is lacking and an altogether different method of tuning for fuel injection is needed.

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