3.0D What’s your hand calculated DIESEL mileage?

SecondTJ

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It will be slightly different. Use this link to type in your own numbers. http://www.grimmjeeper.com/gears.html

play around with it

these are the ZF 8HP75 transmission numbers.

Ratio 1= 5.0000 2= 3.2000 3= 2.1429 4= 1.7200 5= 1.3139 6= 1.0000 7= 0.8221 8= 0.6400 Rev= 3.4560

stock @ 70 MPH would turn 1701 RPM
37's on 4.10's @ 70 MPH would turn 1688 RPM
Those are the wrong gear ratios. Not a big difference but here are the correct ones:

1st: 4.714

2nd: 3.143

3rd: 2.106

4th: 1.667

5th: 1.285

6th: 1.000

7th: 0.839

8th: 0.667





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JTRdiesel

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Those are the wrong gear ratios. Not a big difference but here are the correct ones:

1st: 4.714

2nd: 3.143

3rd: 2.106

4th: 1.667

5th: 1.285

6th: 1.000

7th: 0.839

8th: 0.667
actually those are the ratios for the 8hp70 in that was behind the previous generation of EcoDiesel in the grand Cherokee and ram 1500. The ratios Motoristx stated are the correct values.
 

SecondTJ

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actually those are the ratios for the 8hp70 in that was behind the previous generation of EcoDiesel in the grand Cherokee and ram 1500. The ratios Motoristx stated are the correct values.
It has not changed. FCA uses the same forward gear ratio set on 8HP75 as the 850RE, 8HP70 and even 8HP90
 

JTRdiesel

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Anyone able to tell me what your RPMs are stock at 70mph? @SecondTJ ive got conflicting pieces of information from various sources including FCAs euro and North American websites, my Jeep still hasn’t arrived yet so I can’t confirm myself.
 

SecondTJ

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Motoristx

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Thanks guys, I went back and fixed my post with the transmission gearing so I wouldn't be confusing anyone.
 

WVB

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Two tanks. 1st was 24.5.(40/60 hwy/city) 2nd was 27.2 (70/30). All stock for now.
Computer showed almost exactly 2mpg better than the real numbers
 
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purple haze

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First tank 29 on the dash and 29.7 calculated driving mostly highway. Thats with me taking it easy and going the speed limit. Second tank dash is reading 31.3 with half a tank left. Anyone else notice the trans shifting too early into second gear.
 

No Spark V6

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1700 miles on the odometer, avg 26-27 mpg, used a little less than 1/4 tank of DEF. Assuming the gauge is accurate and linear(not holding my breath), I'm pretty happy.
 

rickinAZ

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I must be heavy-footed. I have 800+ miles on 35s and my average is in the 19s. Almost all in-town miles. They say that elections have consequences. I say that access to all of that torque has consequences as well. :)

BTW the 19s are 6 mpg better than my JK on 35s in the same driving conditions.
 
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JLURD

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I must be heavy-footed. I have 800+ miles on 35s and my average is in the 19s. Almost all in-town miles. They say that elections have consequences. I say that access to all of that torque has consequences as well. :)

BTW the 19s are 6 mpg better than my JK on 35s in the same driving conditions.
This is the sort of comparison which is vastly more useful than the standard nonsense about the monroney mpg vs actual when most of us heavily modify these things and stuff the skinny pedal frequently because it’s great fun. Your 40% increase in mpg compared to a JK similarly outfitted and in the same driving conditions computes with the 35% increase I’ve seen between my ‘18 JLUR 3.6 and ‘20 JLUR 3.0 with the former on 33s and 35s and the latter on 35s and 37s.
 

KevinD

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Been doing it for years on my JLUR, wife’s compass and two prior VW diesels without issue...have you run into this problem?
I've had two different cars have issues: a Ford & a Mercedes.
It's a real PITA when you can't even run the pump on the first notch without it clicking off. Takes FOREVER to get a fill.
And yes, the problem was verified by the dealer, as having come from overfilling. Too expensive to have it corrected on the Mercedes, and I simply got rid of the Ford.
 

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