Lower fuel consumption, low greenhouse gas emissions and high specific performance are commonly known demands for the automotive industry to meet, minding always the sustainability. As a result, the engine downsizing is being largely applied by engine developers, providing further improvement for the components precision, especially in the Flex Fuel applications.The dimensional specification of the engine components plays a very important role in the compression ratio (CR) which impacts directly in the engine performance. Therefore, the objective is to diminish the CR tolerance so we could achieve a much controlled engine. Knowing which parts to improve is the key to success.This paper presents a study of the variation of the CR in accordance with the changes of dimensional characteristics of the studied components. It is possible to estimate which of the components has a greater influence on the variation and then focus on an improvement. Several features were analyzed such as single-valve versus multi-valve cylinder heads and what should be done to ensure a greater repeatability and assertiveness of the CR during the engine serial production.