This report summarizes the work completed in a two year Gas Machinery Research Council (GMRC) project to investigate power loss in compressor manifolds. The project successfully addressed the research objectives, which are: 1. Develop an approach to accurately quantify the power loss in the compressor pulsation control devices in oscillatory (pulsating) flows that can be used by the industry. The recommended approach is called the Flow Energy method. This method is proposed as a technique to be used during the pulsation study conducted at the compressor facility design stage to assess power loss. The mean and fluctuating pressure and flow results that are calculated from the pulsation study are required to calculate the power loss using the Flow Energy method. 2. Investigate if literature values of pressure loss coefficients for common pulsation reduction elements in steady flows are valid for pulsating flows. The pressure loss factors measured for a manifold with a choke tube were shown to be significantly different from loss factors typically used by the industry. Differences were found with mean flow alone and with mean and dynamic flow. The loss factors also varied with the choke tube end treatment design. Loss factors for orifice plates were consistent with industry information. Additional work can be done in future to determine appropriate loss factors for common manifold internal designs so designers have better reference information for simulating compressor systems.