Walter Hake:
Do you know of a Sundowner that has a fuel flow transducer mounted? if so, do they have a photo or drawing? I am considering an installation and have an idea; but it looks like a FUN project.
Editor:
I don’t know of one personally, Walt, but you can always post the question in a Forum. Someone probably has one.
Personally, I have never thought them (fuel flow monitor) to be worth the money on our planes, with the possible exception of someone flying a rental they aren’t familiar with. We don’t have the issues with bladders and compound tanks, that plague some owners of other models. The monitors are no more precise than what you tell them that you put in the tanks. Anyone who owns one of the planes should know within a half-gallon per hour what they will burn at the power settings they use. Our tanks are predictable (no bladders, no compound tankage). It is a rare day when I land and can’t predict within less than one gallon what it is going to take to refill either tank to the tab, slot or top.
In both of my tanks, I have an actual usable capacity of 29.5 gallons. If the fuel completely covers the bottom of the tank, and is just slightly up the forward stringer at the front forward corner, I have ten gallons. To the tip of the tab is fifteen gallons. If the slot is completely covered, I have twenty gallons. Full to the lower side of the cap ring is 29.5 gallons.
In my opinion it is far more important to spend the money on something like a JPI700, before spending any on a fuel flow indicator. Having said that, if you will be installing something like the FS450, it has to go in as the last component before the carburetor. Some of the planes have the boost pump tee-d in between the engine-driven pump and the carb, while on others the boost pump feeds through the engine-driven pump. The transducer has to be installed so that all the fuel used goes through it, so it has to be beyond any pump connections (between the last pump connection and the carb). For example, on the FI Continental-engined planes, with their recirculating fuel injection system, the transducer has to go in the line between the servo and the distributor (spider).
I’m pretty sure you understand what I am getting at. You can put a piece of sealed firesleeve over the transducer, so that heat won’t be an issue almost regardless of where it is located. You can either dress the wires to they exit next to the tubing, or you can slit the sleeve and bring them out the side. You band or tie the ends of the sleeve, and seal the ends (and any slit) using the high-temp red RTV. It comes out quite nice when finished.