Changing the final drive ratio to lower the engine RPM will not necessarily improve fuel economy. It could get worse. At any particular speed it requires a certain horsepower to move a vehicle down a level road. This means that the torque required at the wheels is constant regardless of the RPM of the engine. (If the engine spins faster it has to produce less torque than if it spins slower.) If you happen to have the Brake Specific Fuel Consumption curve for the engine in question, the vehicle drag coefficient and cross-sectional area, then you can probably determine what gear ratio will maximize the fuel economy at a particular speed.
But it is more likely that improving your driving style will have a greater impact on your fuel economy. Bill Bowser - Cincinnati '93 LE 1.8 FMII '05 Lotus Elise '08 HHR SS _______________________________________________ Miatapower mailing list [email protected] http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower
