Workshop Activities

Diesel or Petrol?

When we use energy, heating the home, driving a vehicle, carbon dioxide is produced. There is considerable concern surrounding the effect of global warming and carbon dioxide emissions.

Whichever our choice of fuels available, carbon dioxide will be produced. Carbon dioxide emissions will be produced in ever-greater volume as the size of the vehicle engine is increased.

When fuel is burnt the gasses in the engine combustion chamber are heated and expand very rapidly to force the engine piston down, on its power stroke.

The volume or space into which the burn starts is very significant. A small volume will produce a greater pressure (for the same amount of fuel) and as the volume is less there will be less heat loss to the sides of the combustion chamber.

As the burning gas expands and forces down the piston, the volume around the piston increases. The expanding gas comes into contact with the relatively cool engine metalwork and cools. This cooling effect is a loss of energy transfer to power and reduces engine efficiency.

When the process is compared between petrol and diesel engines, the diesel engine will always be more efficient for comparative levels of technology.

Why?

In a diesel engine the volume into which fuel starts to burn is substantially smaller than the volume found in a petrol engine of the same capacity (cc's or litres volume). If the combustion process starts in a smaller volume of combustion chamber, there is less surface area for heat to be lost to the engine walls. More fuel is used to generate movement and less is lost in wasted heat.

If you care about the environment you will drive a small diesel vehicle.

A partnership established 1983

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The web site sets out typical work undertaken and some technical topics which may interest you.