Does this help?
The heat load to the cooling system is related to the flow through the radiator and the temperature drop through the radiator by the following expression:
Q = M*cp*dT
Where Q is the heat load BTU/min., M is the mass flow rate of the coolant in BTU per pound per degree F, dT is the temperature drop through the radiator in degrees F, and * indicates multiplication. Cosa gallon of coolant weighs about 8.3 pounds, we can replace M in the expression by 8.3 times the coolant flow in gallons per minute, or GPM.
The resulting expression is as follows:
Q = 8.3*GPM*cp*dT