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In recent years, there has been growing interest in alternative cycles to the standard 4-stroke Otto engine for improving efficiency and lowering emissions of spark-ignition engines. One proposed concept is the 5-stroke engine which uses two types of cylinders, a combustion cylinder and an expansion cylinder with a transfer port between them. Excess pressure in the combustion cylinder can be further expanded by using a second expansion cylinder to harness additional work. The expansion cylinder runs on a two-stroke cycle, allowing the use of two combustion cylinders to one expansion cylinder in a three cylinder configuration to increase efficiency. Previous work has investigated the performance of prototype 5-stroke engines compared to 1-D modeling results; none have conducted a thorough study on the interactions of various design parameters.