RemoteTach displays engine RPM for the gear set and tire size you enter into the data fields. It also displays speed in MPH, Altitude, Lat and Lon. This is a great app if you don't have a tachometer or if you want to check the calibration of a tach. You can also type in different transmission and axle ratios to see what your RPM would be if you changed them. You can also change the tire diameter to see how that would effect your RPM at a given speed in a selected gear.
Changes in 1.3:
Removed the ugly white buttons for Analog/Digital and MPH/Km/h select now to select just:
Tap RPM to change from Analog to Digital and back
Tap MPH to change from Km/H to MPH and back
The default data is for a Mustang GT with a 5 speed standard transmission with 17" Wheels.
In the first field at the top (Axle) enter your rear end ratio.
In the second field at the top (Trans)
enter the transmission gear ratio you want the rpm for.
In the third field at the top (Wheel)
enter the diameter (in inches) of your drive tire. Then press Save.
Please note because this app uses GPS data to function you must be going over 5 MPH for it to start calculating.
Calculating RPM from SPEED
The relationship between engine speed (rpm) and road speed (mph) is determined by the characteristics of the drivetrain, from the crankshaft to the tire diameter. To calculate RPM, you will need to know the gear ratio(s) and the final drive ratio, or the overall ratio, and the diameter of the tires connected to the speedometer (usually the driven tires).
The gear ratios can be found in your owner's manual, Google or R&T data panel. To find the tire diameter use a tape measure and measure across your tires
center point from tread to tread.
*For iPhone 3G and 3GS Only*