The use of pressure sensors on slow speed integral engines to measure internal dynamic combustion pressure is well proven and extensive. Such sensors have been used with portable analyzers in the Gas Industry on slow speed 2-stroke and 4-stroke engines for decades to balance combustion pressures and diagnose mechanical problems. Over the last 5 years, a new generation of piezoelectric pressure sensors has been developed for continuous use in large bore 2-stroke and 4-stroke integral engines. It is estimated that in excess of 2000 of these sensors are currently installed in the Gas Pipeline Industry. These sensors have proven extremely valuable as inputs to high pressure fuel injection systems designed to lower emission levels by allowing balancing of engine peak firing pressures, minimizing cycle-to-cycle deviations, misfires and detonation. Evidence also suggests that operators are realizing reduced costs in fuel and maintenance expenditures.The use of dynamic pressure sensors on high speed 4-stroke engines has been extremely limited. This is due to the lack of a convenient indicator port as is found on most large bore integral engines. Over the years, innovative users have attempted to use various pressure sensors for test purposes. The sensors have been installed in a variety of ways, such as modifying spark plugs with piezoelectric sensors. However, due to limitations in cost, ruggedness and maintenance considerations, the sensors have not been used extensively. The paper will present the results of the first large scale application of dynamic pressure sensor monitoring on high speed 4- stroke engines in the Gas Industry. We have now installed head bolt sensors on two CAT3608 engines with 8 more installations to followat BP’s San Juan Basin Operations. The paper will describe the innovative way the sensors are installed, special mounting considerations and calibration techniques. The monitoring system architecture and networking infrastructure will also be presented along with a discussion of how the combustion data can be used to enhance engine operations in the Gas Industry.