The ______ mounts on the intake system between the turbocharger and throttle body and prevents the ducting from blowing apart.

• A. Radiator intercooler
• B. Crankcase breather
• C. Blowoff valve
• D. Throttle body spacer

Answer: (C)

When the turbocharged system experiences a sudden throttle closure, boost pressure wants to keep building. A blowoff valve sits in the charge-air path between the turbo and the throttle body to vent that excess pressure, preventing the ducts from surging or blowing apart. It protects the piping and reduces compressor surge by releasing the pressure either back into the intake or to the atmosphere, depending on the design. The radiator intercooler is there to cool the charged air, not to relieve pressure. The crankcase breather handles crankcase gases, not boost pressure in the intake. A throttle body spacer changes intake geometry but doesn’t vent boost. So the best choice is the blowoff valve.