I moved the oil cooler from the baffle to the firewall and not pleased with the increase in oil temp.
I have a theory and need an engineering point of view.
When a cooler is mounted on the baffle, the front surface area equals the back surface area. Since the air pressure is higher in the area where the air has not cooled the engine yet (baffle box), the higher pressure gradient forces the air through the cooler from the baffle box to the remainder of the cowl.
For the sake of argument, let's assume the baffle box has a pressure 3 times what the remaining cowl has.
When you mount an oil cooler on the firewall and feed it with a 3" scat tube, the surface area coming into the oil cooler is almost 1/3 that of the back side where the air exits. If that is the case, then the pressure gradient is reduced by 3 times and it becomes difficult for air to exit the cooler since the exit pressure is close to the pressure inside the cowl.
Based on this assumption, if one was to make a reducer for the back side of the cooler with the same surface area as the front, then the pressure would theoretically drop from 3 in the scat tube to a lower pressure in the cooler equal to the cowl pressure and then would be then increase again upon leaving the cooler through the surface area reducer. This increase in pressure would allow the air exiting the cooler to return to baffle box pressure, therefore overcome the lower pressure in the cowl.
My gut is telling me that airflow has been reduced by the inability of air exiting the cooler to overcome the pressure gradient. Application of a venturi effect on the exiting air will take care of this issue.
I have a theory and need an engineering point of view.
When a cooler is mounted on the baffle, the front surface area equals the back surface area. Since the air pressure is higher in the area where the air has not cooled the engine yet (baffle box), the higher pressure gradient forces the air through the cooler from the baffle box to the remainder of the cowl.
For the sake of argument, let's assume the baffle box has a pressure 3 times what the remaining cowl has.
When you mount an oil cooler on the firewall and feed it with a 3" scat tube, the surface area coming into the oil cooler is almost 1/3 that of the back side where the air exits. If that is the case, then the pressure gradient is reduced by 3 times and it becomes difficult for air to exit the cooler since the exit pressure is close to the pressure inside the cowl.
Based on this assumption, if one was to make a reducer for the back side of the cooler with the same surface area as the front, then the pressure would theoretically drop from 3 in the scat tube to a lower pressure in the cooler equal to the cowl pressure and then would be then increase again upon leaving the cooler through the surface area reducer. This increase in pressure would allow the air exiting the cooler to return to baffle box pressure, therefore overcome the lower pressure in the cowl.
My gut is telling me that airflow has been reduced by the inability of air exiting the cooler to overcome the pressure gradient. Application of a venturi effect on the exiting air will take care of this issue.