Trends of the automotive market require the application of new engine technologies, which allows for the use of different types of fuel. Currently available multi-fuel engines operate with constant compression ratio irrespective to the fuel being used, however for best performance the engine should work with a variable compression ratio. Although technically possible, this is not considered feasible for a low-cost product. In order to circumvent this and other losses, it was devised an innovative approach, which adopts turbocharging to allow optimum performance for different fuels, without changing compression ratio, an advance that can be added to low cost products. Alternatively, this approach can be used as an optimization tool along more conventional engines development. This advance will be implemented into a 1.3 8v FIRE FLEX MULTI-FUEL engine capable of operating with Gasoline E25, E94 ethyl hydrate, any blend of Gasoline E25 and Alcohol E94, and natural gas. The previous methodology developed to adjust and calibrate the EMS in  was modified to allow gaseous fuel control. Before the adoption of turbocharging, it was necessary a careful study of the naturally aspirated version with different compression ratios to investigate how the compression ratio influences the engine performance for each fuel used. This paper discusses in details this investigation. Subsequent work with turbocharging is intended to be presented in future papers. All the results of the naturally aspirated engine This proposal can be used for some applications, giving the possibility to the automotive industry to utilize this engine system either to optimize the multi-fuel engines or to produce the same engine in the world for all types of gasoline for example, decreasing the cost of the production.