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RPM to MPH conversion

Does anyone know the RPM to MPH conversion for a Honda Civic DX 1992 manual gearbox?


  • edited December 2010
    No, we do not know that..Why would we care?? Why do YOU care??

    To figure it out, you need to know three things..The final drive ratio of the transmission in top gear..The differential gear ratio (final drive ratio) and the circumference of the tires on the car... There are 12" in a foot and 5280 feet in a mile...Go for it......
  • edited December 2010
    Because his speedometer broke and he's trying to determine speed from RPM ;)

    Why no, that has never happened to me. Ever. And I wouldn't lie about a thing like that ;)

  • edited December 2010
    You find one of those "Your Speed Is" radar display trailers the cops use here and there and make a RPM to speed conversion chart...
  • edited December 2010
    I believe its only going to give him a general idea as the rpm should change compared to mph per incline blah blah blah
  • edited December 2010
    Caddyman might need a vacation
  • edited December 2010
    I'm on vacation NOW..Two Martini's, that's the problem...
  • edited December 2010
    Thanks for the Laugh :-)............
  • edited December 2010
    For each gear the ratio would be different. Four thousand RPM in first gear might be around 30 MPH, in second gear around 40 MPH, in third gear around 55 MPH, in fourth gear around 65 MPH and in fifth gear around 75 MPH. If you have five manual gears.

    You should drive in the highest gear possible at all times. If you can keep the tachometer below 3,000 RPM's most of the time, you will have your car for a long time.

    Otherwise, to avoid speeding tickets, just match the speed of traffic on highways and go slower than necessary on single lane roads.
  • edited December 2010
    I used to ride an inter-city bus to and from college that was probably built just after WW II. The tachometer served as the speedometer. It had a scale in MPH for each of the 5 forward gears in the transmission. This was a Flxible (yes, the spelling is correct) body on a GM chassis. I suppose you could do the same with a little calculation if you knew the ratio of each of these gears and calculted that against the final output to the wheels. You would have to take into account the diameter of the wheel.
  • edited December 2010
    If your speedometer is busted, get a GPS. It will give your speed and miles traveled.
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