acdii Report post Posted February 10, 2013 Been doing some research into the best MPG at 206* coolant theory. I came across a PDF from Cummins regarding fuel efficiency, while geared towards Semi's, it relates in general to all vehicles. From what I read there, if our cars are running cold, this would explain the loss of MPG that we are experiencing. Hope this link works to the doc.http://www.google.com/url?sa=t&rct=j&q=engine%20temps%20for%20best%20mpg&source=web&cd=10&ved=0CJwBEBYwCQ&url=http%3A%2F%2Fwww.nptc.org%2Findex.php%3Foption%3Dcom_docman%26task%3Ddoc_download%26gid%3D419%26Itemid%3D230&ei=gwgYUeCtHInc2AXCgoHIDA&usg=AFQjCNGlRGZ-_0ShASaTT2DtFTO0y6fMUg&cad=rjaEngine Operating Temperature (Coolant and Lube Oil)Low coolant temperatures indicate an engine that is too cold for efficient combustion. Fuel liquefies on the cold cylinder walls and fails to burn. Of course, excess heat causes engine failure.Lube oil below the ideal temperature is more viscous and harder to pump. Oil above the ideal temperature is too thin to lubricate properly. Either way, the engine suffers.Coolant and lube oil operating temperatures can contribute greatly to fuel efficiency. Typical cooling system operating temperatures are above 180° F. A 0.4% fuel economy loss is associated with every 30° decrease in temperature.Lube system operating temperatures run above 225° F, and a 1% fuel economy loss is associated with every 30° decrease in lube temperature. I have also perused a few non Ford forums, and in the TDI one, they found that installing a 195* T-stat helps improve MPG. Since my scan gauge has been showing temps of 160* for most of my drive, that explains a lot, and the engine rarely reaches 180*, usually only after a brief heat soak at a stop, and quickly drops when I start moving again. There was only one time I saw 190 and that was driving with the HVAC turned off. Blocking the grill holds a lot of truth, less airflow through the radiator helps hold the heat in, but if the cooling system is working too well, all the blocking in the world wont help. One of the things that holds true, on every power stroke, if the engine is cold, it absorbs a portion of that heat, resulting in lost power, The higher the cylinder head temps, the more power is returned for the gas used. The end result is lower fuel consumption. A colder running engine may also never go into fully closed loop function, which is the same as running with a partially closed choke. It has been at least a decade or two since I cracked open a book on this when I was working as an ASE mechanic, but I still remember a bit of it. Sure was a lot easier than the Cisco stuff I work with today, but then again, the pay is also a lot better for the Cisco stuff than turning a wrench. 1 ptjones reacted to this Quote Share this post Link to post Share on other sites
