....diverted to a external transmission cooler that is located in front of the radiator. Fuel is then cooled before it returns to the tank. So, fuel is first heated by a liquid to liquid heat exchanger and then excess fuel is cooled by a air to liquid cooler...both originally designed to cool transmission fluid.
This little modification has succeded in picking up 3-4 mpg...going from an average of 33mpg to 36-37 mpg. A gain of 10%. I am in the process of putting together a MPI system for my Cad 500, so I have a similar heater that I plan to install in the heater line going to the house hot water heater. I plan to put in a cut-off valve to stop the hot water should I develop problems with the experiment.