RPM's auto vs manual

[wpurple]

97 Sport 3.73 5 spd manual 65=2200rpm (in 5th)
99 Mountaineer 3.73 automatic 65=1975 rpm (in OD)
both final ratio's are 0.7
speed monitored using GPS, rpm monitored using OBD-II monitor....

both have the same size tires....what gives?

 

[Electrohacker]

I get a similar reading in my 96 V8 auto AWD, but I use the tac...

 

[F14CRAZY]

That's one of the good things about a manual. RPMs are lower. One reason is that a manual doesn't waste as much power as an auto, which is why manuals get better gas milage.

 

[Electrohacker]

did you read the post...

the automatic was lower...

 

[wpurple]

Yes, automatic is lower! I would think that we are able to compare apples to apples since these days the torque converter locks up.

Now that I put the original 3.27's back in my Sport, the RPM's are the same as my 99 Mounty with 3.73's.

ODD.

 

[hunterep]

Hey

I guess thats why they make a final drive ratio with 2 numbers instead of one. On the manual its .79 and on the auto its .75. It also might make a difference in mpg. You also have to account for the weights of the vehicles. Since all cars today answer to a computer before the pedal! I know driving with a head wind will up my rpm by 300.

Hope that made since!!

James