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NovaResource -> RE: Proper RPMs for 2001 Sonata (3/31/2008 10:01:03 AM)
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quote:
ORIGINAL: nmunafo I recently purchased a 2001 Sonata. However, during the first week, the transmission went, and had to be replaced by the dealer (with a used one). Silly me, I did not find out what transmission he replaced it with - the 3 speed or the 4 speed (It had had the 4-speed). It seems to me that the car is running at higher RPMs during highway driving than I remembered it doing before. When I drove in to work today, it was doing about 2750 RPM @ 75 MPH? Does anyone have a table of the RPMs a motor should be doing at a given highway speed, and would a different speed transmission change that noticably? Is the 2750RPM @ 75 MPH excessive? It sounds totally, 100% correct. It's simple math. Let's start with the known facts: 2001 Sonata automatic: - 1st gear ratio = 2.842 - 2nd gear ratio = 1.529 - 3rd gear ratio = 1.000 - 4th gear ratio = 0.712 - Final gear ratio = 3.770 So when in 4th gear at 2750 engine RPM's the wheels are turning 1024.5 RPM. 2750 / 0.712 / 3.770 = 1024.5 Original tires: - 205/60-15 The diameter of that tire is 24.7" and that tire has 817.4 rev per mile. So if the wheels turning 1024.5 revs per minute, multiply that by 60 and you get 61,470 revs per hour. Now divide that by the tire rev per mile (817.4) and you get the Miles Per Hour. 61,470 / 817.4 = 75.2 mph For the record, speeds in 4th gear at indicated engine RPM: 1500-rpm = 41-mph 1600-rpm = 44-mph 1700-rpm = 46-mph 1800-rpm = 49-mph 1900-rpm = 52-mph 2000-rpm = 55-mph 2100-rpm = 57-mph 2200-rpm = 60-mph 2300-rpm = 63-mph 2400-rpm = 66-mph 2500-rpm = 68-mph 2600-rpm = 71-mph 2700-rpm = 74-mph 2800-rpm = 77-mph 2900-rpm = 79-mph 3000-rpm = 82-mph
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