Joe wrote- >I have no data to compare as it was built like this from the get go >but I do know that my fuel pressure from the header tank (gravity feed) >has never been below 8/10 of a pound even though mathematically >that should be impossible given the height of the tank at low fuel level >above the pressure sensor.
Joe; how did you figure the math? With, or without, ram air pressure? To get 0.8 psi by gravity head alone, the difference in elevation between the static fuel level in the header tank and the place where you measure fuel pressure (presumed to be the inlet to the float bowl) would need to be a little over 22" depending on what fuel you're running and its specific gravity. That's a law of physics that can't be altered unless you are on another planet where the force of gravity is different, or if you are somewhere near Groom Lake in Area 51, and all bets are off. However, if you were referring to your static head *plus* ram air pressure at cruise, it's not a stretch because (example): at 124 MPH, the stagnation (ram) pressure of air at STP is about 0.3 psig, so your gravity head of another 0.5 psig would be an elevation difference of a little less than 14" between static fuel level in the header tank and the inlet to the float bowl. Probably not unrealistic for your setup. Whatever the case, you've seen 0.8 psi at the carb with your setup, and there is no arguing with that. Good info. Oscar Zuniga Medford, OR
