i am building a hydrogen fuel cell to put in my car will it hurt my car?

i have a 1980 pinto and its an older car and i know that a hydrogen fuel cell can duble mpg and boost power by burning the gas faster and burning more of it and i wonted to know if it wuld heat up my car to much or somthing?
im 15 yrs old and a hidrogen fuel cell is VERRY easy to build……..and can it over heat my engine?