Oh yeah, loved Gallagher!
Gears and lockers
- Thread starter tristan6555
- Start date
Oh yeah, loved Gallagher!
I wonder what the mpg difference would be doing 60 down the highway between 4.56 and 4.88
I have to drive 30 minutes to get to any kind of town that has big box stores. From what im hearing from everyone on here im thinking the 4.56 might be what I need
I don't have the 4.88s personally as a point of comparison, but because I did have the 4.10s and do have the 4.56s I can give you that. Our mountain highways are usually 65mph while the plains interstates are 75 or 80mph.
With the 4.10s because the gearing put the rpm lower making less power and forcing you apply more throttle many times, I basically got 13.5mpg everywhere.
With the 4.56s it's much better aligned with the power band and I get 15.5-16.2mpg now on highways at 55 to 65mph. The aero gets much worse at 75+ and my fuel economy generally drops down to 14.5-15 mpg. It can get worse in a Wyoming headwind. I'd wager you could squeeze another 0.5mpg by running the tires at 35psi, but the ride would suck.
You'd have to have an identical build or same jeep scenario because from one to another weight and tire choice and top and accessories will make so much difference.
If I had to place a bet on it I'd wager 4.56 and 4.88 are the same but 5.13 gets worse (with the 5-speed]
How much time do you actually spend on the freeway doing 70+ mph?
Is saving a couple minutes travel time that important compared to just going 65?
4.88 will make it more enjoyable,and you'll get better fuel economy in a lifted jeep by staying at lower speeds.
Lower rpm with your foot to the floor is going to burn more fuel than higher rpm and less throttle input.
You'll enjoy it much more offroad too. The clutch action is way easier.
we already know it’s completely negligible.
I’ve got gas mileage records back to 2017. Those records for the 6-speed were on 31’s and 3.73, 33’s and 3.73, 33’s and 4.56, 35’s and 4.56. With an auto they are for 35’s and 4.56 with OEM PCM and 35’s with 4.56 with WranglerFix PCM and these are results for all driving.
About 13.5mpg for 31’s.
Everything else 12.4mpg
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Now teach him to measure his effective rolling diameter to use for the calculation.
And then to interpret any data the calculator gives in a way that helps on the road and trail
Thank you for that. That was cool. 4.56 is exactly what im looking for according to that if im sticking with 33s.
You aren't paying attention. Your effective rolling diameter is not 33". And you really do want more rpm at 75mph.
If you're worried about mileage, you're driving the wrong vehicle!
Go for a drive on the highway and record the rpm at a specific highway speed on 5th gear. 70mph is easy because GrimmJeeper is preset for that. Use GPS if the speedomter is off.
Then go back to GrimmJeeper and enter in the Jeep's current details. Then adjust the tire size until 70mph matches the rpm you recorded on the highway.
That is your effective tire diameter that you use to figure this stuff out. This is the same measurement as the hub center height off the ground times two, depending on how accurately you can use a tape measure.
After that, find a gear ratio that gets you close to 3000rpm at 75mph.
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O I know but I still want to try to push it for everything its worth.
After 8 years of keeping up with my mileage, you are never talking more than 1mpg and you may actually improve your mpg with deeper gearing due to mechanical advantage. Stop thinking rpm’s have a direct correlation with mpg.
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