The result of your conversion between Btu and grain/cubic inch appears here
To convert between Btu and Grain/cubic Inch you have to do the following:
First divide 1055.0559 / ((0.45359237/16)*(192/175)/480)/(0.0037854118/231) = 266.81418916
Then multiply the amount of Btu you want to convert to Grain/cubic Inch, use the chart below to guide you.
Symbol: Btu
No description
Symbol: gr/in³
No description