mph/rpm in an auto?

[vr41mpg]

Hey I was curious at what rpm the auto transmissions cruise at various speeds (20, 30, 40, 50, 60, 70 mph) I am trying to get a feel for how it would drive if I were to put a w4a33 in my GVR4. Is there any mod similar to the AWD Transmission to make a taller 5th (or i guess a taller 4th) for lower rpm on highway cruise?


How would the 2g w4a33 4th gear compare to my setup now with the 10% taller evo3 5th gear? I think 'm at 65-70mph at 3k.

 

[nek]

Hey I was curious at what rpm the auto transmissions cruise at various speeds (20, 30, 40, 50, 60, 70 mph) I am trying to get a feel for how it would drive if I were to put a w4a33 in my GVR4. Is there any mod similar to the AWD Transmission to make a taller 5th (or i guess a taller 4th) for lower rpm on highway cruise?


How would the 2g w4a33 4th gear compare to my setup now with the 10% taller evo3 5th gear? I think 'm at 65-70mph at 3k.

Sounds about right, Im at about 26-2800 rpm at 65 cruising in od

 

[Doubleot]

Yep sounds right on. 3k OD on and 70mph

 

[LxiMax]

I sit right at 2200-2300 in OD at 55mph.

 

[rEclipserGST]

3000 rpm @ 73 mph in OD

 

[19Eclipse90]

These assume a 25" diameter tire and should get you in the ball park. The ratios used were pulled from a '92-'94 and a '98 FSM, respectively; the gear ratios themselves are exactly the same but the final drive is different (4.421 for the 1G vs. 4.359 for the 2G) which makes the results slightly (practically negligibly) different as well. The different colors represent the different drive gears, obviously from 1st on the left to 4th on the right.

 

[vr41mpg]

thanks!

ok so lets say you are cruising at 55mph in OD and you want to WOT in order to get in front of the person beside you. the automatic will shift down to 3rd right? what rpm would it be at? like 4k? what if you did this starting at 70mph in OD?


lets say you are cruising around town at like 30mph, 40mph. does it stay in 3rd at these speeds? at what point does it shift into 4th? if I have a ratchet shifter can I shift it at will or is it only at WOT?

thanks im using this information to help in my turbo decision.

 

[Bud92gsx]

Get a shift box, and manually shift. Saves gas when only cruising.I went from the factory 18 mpg on the 1g auto to 22+ manually shifting at lower rpms.

 

[19Eclipse90]

ok so lets say you are cruising at 55mph in OD and you want to WOT in order to get in front of the person beside you. the automatic will shift down to 3rd right? what rpm would it be at? like 4k? what if you did this starting at 70mph in OD?

This information can easily be estimated from the graphs provided if you assume the instantaneous speed stays constant during the gear change.

If you are at 55mph in OD and it shifts down to 3rd, follow the 55mph mark up vertically from the yellow line to the red line. Trace that point to the left to the RPM and you'll have your answer for any combination of speed, gear, and rpm you can think of within the range of the graph. For this case, the RPM will jump by about 1000 from 2250 in OD to 3250 in 3rd.

Same procedure for your other hypothetical, but instead you start at 70mph rather than 55mph. It looks like about 2900 in OD to about 4200 in 3rd.

Again, this isn't exact but will get you a decent ballpark figure for whatever combination of gear-vehicle speed-RPM you're interested in.

 

[vr41mpg]

if I get the shift box do I have to shift it myself all of the time? I'm sorry I haven't done all of my reading and searching yet on this subject but since you bring it up I figured I'd ask.


part of the reason I want an automatic is for driving in rush hour so I wouldn't want to have to manually shift it all the time. from my brief reading on this I thought i was going to get a TCU and do the full line pressure mod with a ratchet shifter to shift manually when WOT.


also are those graphs correct for 2.0 and 2.3L? would displacement change the graphs at all? I know you said tire size would but is there anything else that would effect it?

bigger tire = higher or lower rpm for a given mph? was thinking about going 17x8.5

 

[19Eclipse90]

also are those graphs correct for 2.0 and 2.3L? would displacement change the graphs at all? I know you said tire size would but is there anything else that would effect it?

bigger tire = higher or lower rpm for a given mph? was thinking about going 17x8.5

Displacement has nothing to do with it; 1 rpm on a 2.0L is the same as 1 rpm on a 2.3L and 6352 rpm on a 2.0L is the same as 6352 rpm on a 2.3L. Those graphs are based strictly on tire size (diameter specifically) and the respective gear ratios.

A larger diameter tire will cover more ground per rotation, so a larger tire will give a lower RPM for a given MPH.

Spend some time playing with tire size calculators. Specifying a "17x8.5" tire tells us nothing about the tire diameter as the sidewall aspect ratio is missing and is vital to the calculation.

 

[reyg]

A little off the subject mind of if I am making 15 hour transit is driving @ 70mph and 3000 ish rpm going to be fine?

 

[19Eclipse90]

If the vehicle is mechanically sound, you will have no issues.

DSMs on Long Trips