What does 1.8td mean?

In 1.8td, the T stands for turbocharging and the D represents direct injection technology, specifically in-cylinder direct injection turbocharging technology. The functions of turbocharging and its differences from other engine types are as follows:

Main functions of turbocharging:

Increases engine air intake, thereby enhancing the engine's power and torque, resulting in greater vehicle horsepower. When a turbocharger is fitted to an engine, its maximum power can increase by 40% or more compared to the same engine without a turbocharger. Essentially, turbocharging improves fuel economy and reduces exhaust emissions.

The difference between in-cylinder direct injection engines and port fuel injection engines is:

Under high or full load conditions, in-cylinder direct injection engines inject fuel into the combustion chamber during the intake stroke. As the fuel spray moves slower than the piston's downward motion, the pressure around the fuel spray decreases, allowing rapid fuel diffusion and vaporisation, thus forming a homogeneous combustion mixture. The heat absorbed during fuel evaporation lowers cylinder temperatures, enhancing anti-knock performance. This enables in-cylinder direct injection engines to operate with higher compression ratios, improving thermal efficiency.