This paper is a case study of the effects of crankshaft configuration and crank referenced unloading devices on engine speed variations. Specifically, the paper focuses on a severe engine speed variation (+/-50 rpm) problem on an Ingersoll-Rand KVSR-412 fitted with a Hoerbiger HydroCOM unloading system. The case study discussed the troubleshooting process used to identify the problems, symptoms, and remedies applied in an effort to eliminate or reduce the speed variation problem. Several basic tests and remedies were applied but none satisfactorily resolved the problem. After further investigation, two primary problems were identified for further investigation and testing. Hoerbiger addressed both of these problems and the speed variation problems were corrected. The most interesting part of this problem was not the solution but whether similar problems exist on high-speed tandem mounted compressor and the angles at which they are coupled to an engine.