Carburetor:
* Mechanism: Uses airflow to *atomize* and *mix* fuel with air. Venturi effect (a narrowing in the airflow path) creates a low-pressure area which draws fuel from a reservoir into the airstream. The fuel/air mixture is then drawn into the engine's cylinders.
* Fuel delivery: Mechanically controlled, often using a diaphragm or float system to maintain a consistent fuel level.
* Mixture control: Provides a single, relatively crude mixture for all cylinders across the engine's operating range. This requires complex internal mechanisms like choke and accelerator pumps to adjust for different operating conditions (cold starts, acceleration).
* Simplicity: Relatively simple mechanically, but can be prone to adjustments and tuning.
* Efficiency: Generally less efficient than throttle bodies, especially in terms of fuel economy and emissions, due to inconsistent fuel/air mixing.
* Used in: Older vehicles, some small engines (like lawnmowers), and some specialized applications.
Throttle Body:
* Mechanism: A butterfly valve controlling the amount of air entering the intake manifold. Fuel is injected separately into the intake manifold, often by electronic fuel injectors.
* Fuel delivery: Electronically controlled by an Engine Control Unit (ECU), delivering precise amounts of fuel based on various sensors' input (e.g., airflow, engine speed, temperature).
* Mixture control: Allows for precise control of the air/fuel mixture for optimal combustion across the engine's operating range. This leads to better efficiency and cleaner emissions.
* Simplicity: Relatively simple in design, but sophisticated electronically.
* Efficiency: Much more fuel-efficient and environmentally friendly due to precise fuel metering and consistent air/fuel mixture.
* Used in: Modern vehicles and most fuel-injected engines.
In short: A carburetor mixes fuel and air mechanically using airflow, while a throttle body electronically controls airflow, with fuel injection handled separately and more precisely. Throttle bodies represent a significant advancement in fuel efficiency and emissions control over carburetors.
