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Best RPM for gas mileage?

11K views 29 replies 11 participants last post by  debruins 
#1 ·
So I'm usually pretty nice to my Jeep, sometimes I spin it high but usually on the street it doesn't come above 3g. A lot of the time I find myself bogging it a little, just like 1200-1300rpm, maybe even lower. I assume that being easy on the pedal increases gas mileage, but probably only to a point. Is there an optimum RPM for gas mileage? Should I have it pretty low or more around 2000? Thanks guys
 
#3 ·
my auto tranny always shifts at 1800-2500 rpm.
at 65 mph i have about 2000 rpm. and the gas mileage became much better after regearing.

with manual tranny i drove in the highest gear that was able to hold he speed.
mith the manual tranny the mileage was better than with the auto tranny.
 
#5 ·
with the 3.07 gears and the 35s the 4th gear with OD wasn´t able to hold the speed at 65 mph. with the 3rd gear it was about 3000 rpm at 65 mph.
i got 12-13 mpg with that setup.

now with the 4.56 gears and the 35s i have about 2000 rpm at 65 mph.
i get 17-18 mpg with that.

in the city with stop and go traffic it goes down to 11 mpg, but most of the time it´s 13-14 mpg. before it was only 9 mpg sometimes.

with manual tranny it should be 2-3 mpg more.
 
#9 ·
The most efficient rpm is around 2500 with the 4.0. With my XJ, 3:07's, LT235's, I use 4th and stay in 4th till I get above 70, after that it goes into 5th. At 60 in 5th it won't accelerate. The TJ with 2.5, 5 speed, 4:10's and 30's wants 2800, again 4th till 60ish then 5th.
 
#10 ·
I had 30's with 3.73's which ran at around 2600 at 65. Now with the 33's and same gears, its at 2100 at 65. Im getting way better mileage on the highway. I have to figure out how to estimate mpgs. I would say lower rpms is better for mpg.
 
#11 ·
With my rig I think the closer to 3K the better. My Rubi gets just about .5 mpg better when I run the trip home (25 miles of flat highway section) in 5'th gear instead of 6'th. Which puts it right about 2900 rpm @ 73 MPH vs 2650 RPM in 6'th gear

33's with 4.10 gearing with a manual tranny.
 
#12 ·
With my rig I think the closer to 3K the better. My Rubi gets just about .5 mpg better when I run the trip home (highway section) in 5'th gear instead of 6'th. Which puts it right about 2900 rpm @ 73 MPH vs 2650 RPM in 6'th gear

33's with 4.10 gearing with a manual tranny.
:eek: Damn and I usually try to keep it under 2000. Boy was I wrong. :doh:
Thats why I posted this thread. Sounds a lot better over 2k anyways. The exhaust leaks get drowned out by the exhaust itself. ;)
 
#22 ·
Here it is...it has better looking wheels now, but overall doesn't look so great. Its wetsanded primer. But I'll paint it soon and then work on the motor and drivetrain and all that, In memory of my brother; he sold me the car dirt cheap cause I wanted it so bad, so I gotta make him proud.


It will look like:

Something like that but different wheels probably.
 
#24 ·
I have to say that ive driven both auto's and manuals and i will never go back to auto again! IMO manuals connect you to the vehicle so much better than auto's, plus they're a ton more fun to drive :D

Staying on topic, i honestly dont know...i shift at high rpms to make better power with my 2.5 4 banger and i really dont care about gas mileage...if i did care i wouldnt be driving a jeep :D
 
#25 ·
The Mustang is just an eyesore in the driveway for a while. I need to put the driveline in it, the clutch quadrant and firewall adjuster, hook up the clutch cable, and I am missing a small wiring harness, just 2 plugs. Right now it starts from the solenoid under the hood, but not from the key, until I get that bit of wiring. Its got a bunch of back registration I need to pay, I need to smog it somehow...I've really got my hands full with that project. My brother knew every last thing about those cars, had a 500+ hp 88 Mustang with a 410 Windsor, among probably 5 other 5.0's. He was helping me with my car but then he passed so I'm kinda on my own, which is one of the reasons I've just been doing stuff on the Jeep.
 
#28 ·
just to add to the original post, with my 4.0 and manual, i leave it at about 1500, to 2000, then when i want to accelerate i downshift, this is probably more work than most people like, but i find its the best for gas mileage, but i shift like once every 40 seconds when in traffic or more, i find the best cruising RPM is about 1900 and the best accelerating RPM is about 2800
 
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