A carburetor-inspired induction system with a separate throttle body for each engine cylinder, providing instantaneous throttle response and a distinctive intake sound.
Individual throttle bodies (ITBs) replace a single common throttle body and intake manifold with a separate throttle plate for each cylinder. The result is a direct, carburetor-like connection between throttle input and cylinder airflow with virtually zero lag. Because each cylinder has its own throttle plate positioned close to the intake port, the throttle response is nearly instantaneous, giving naturally aspirated engines a hyperresponsive character that pleases drivers seeking mechanical engagement.
ITBs are closely associated with classic motorsport engines and high-performance naturally aspirated builds. BMW's E30 M3 S14 engine used individual throttle bodies as factory equipment. The Honda S2000's F20C and F22C engines used a similar short-runner high-revving intake design. Many engine builders installing ITBs on K-series, SR20, or RB-series engines note dramatic improvements in mid-to-high-RPM throttle feel.
The primary challenge of ITBs is tuning. Because the throttle is so direct and the runner lengths are usually short and equal, the engine needs careful fueling calibration at low throttle openings where idle quality and part-throttle response can be poor without expert tuning. ITBs are not compatible with most modern drive-by-wire emissions setups without significant engineering effort.