The sealing performance of V-insert clamp used in automobile exhaust pipes was examined for various applied torques by a specially designed pneumatic testing system. Axial clamping forces of V-insert clamp were evaluated through a clamping performance test. In the clamping performance test, increase in the torque showed gradual increase in the axial clamping force for all gaps between exhaust pipes that were considered. Slight increase in the torque resulted in relatively high axial clamping force. In the sealing performance test, when applied pressure was 50 kPa, the leak was not present in all applied torques due to no pressure change as a function of time. For 100 kPa, the leak was observed for applied torques of 3 N-m and lower. When V-insert clamp was used to join the pipes together, at least the applied torque of 4 N-m was needed in order for V-insert clamp to effectively function in the exhaustion system. Therefore, it can be concluded that V-insert clamp showed sufficient sealing performance to support the applied pressure of up to 100 kPa within the exhaustion system when relatively high torque was applied.