Thread: SGII MPG Calculation View Single Post
 06-10-2008, 11:10 PM #10 (permalink) LostCause Liberti     Join Date: Feb 2008 Location: California Posts: 504 Thunderbird - '96 Ford Thunderbird 90 day: 27.75 mpg (US) Thanks: 0 Thanked 7 Times in 7 Posts It depends on whether your car has a MAF sensor or not. MAF Sensor: MPG = (14.7 * 6.17 * 454 * VSS * 0.621371) / (3600 * MAF / 100) = 710.7 * VSS / MAF 14.7 - grams of air to 1 gram of gasoline - ideal air/fuel ratio 6.17 - pounds per gallon - density of gasoline 4.54 - grams per pound - conversion VSS - vehicle speed in kilometers per hour 0.621371 - miles per hour/kilometers per hour - conversion 3600 - seconds per hour - conversion MAF - mass air flow rate in 100 grams per second 100 - to correct MAF to give grams per second No MAF (Uses MAP and Absolute Temp to approximate MAF): IMAP = RPM * MAP / IAT MAF = (IMAP/120)*(VE/100)*(ED)*(MM)/(R) MAP - Manifold Absolute Pressure in kPa IAT - Intake Air Temperature in Kelvin R - Specific Gas Constant (8.314 JM/K) MM - Average molecular mass of air (28.97 g/M) VE - volumetric efficiency measured in percent ED - Engine Displacement in liters This method requires tweaking of the VE for accuracy. I have no idea if these are the methods the SGII uses. The accuracy will be off due to approximations (AFR ~14.7, etc). All the information is from the brilliant mind of Bruce Lightner. - LostCause