A forced induction system configuration where the carburetor or throttle body is located upstream of the turbocharger. This setup necessitates the fuel-air mixture to pass through the compressor and intercooler (if equipped) before entering the engine. An example involves modifying a carbureted engine to accommodate increased air pressure generated by the turbocharger, requiring adjustments to the fuel delivery system to maintain the correct air-fuel ratio.
This methodology offers certain advantages, particularly in simplifying the conversion of naturally aspirated engines to forced induction. Historically, it provided a more straightforward route to turbocharging older, carbureted vehicles, circumventing the complexities of early fuel injection systems. The benefits often include a potentially lower initial cost and reduced complexity compared to converting to fuel injection. However, proper implementation and tuning are crucial for reliable operation and optimal performance.