Better EVIC mileage with 4.10 over 3.42

Something is messed up, when I go to fifth at hwy speeds my Mpg drops 2 mpg

NDanecker said:

I'm seeing people with 4.10s getting better mileage than I am with 3.42s. So today as a simple test (final drive with 3.42s in 5th is very close to final drive with 4.10s in 6th) I ran on flat ground in 6th and EVIC showed 17mpg. Switching down to 5th EVIC jumped to 22 and 23mpg --- same speed. I know EVIC is not correct but as a reference tool I think it works well. Thinking of swapping my 3.42s for 4.10. Although I haven't towed heavy with it yet I'm sure she will tow better having more gears to play with 4.10 than keeping it locked out of 6th and playing with 1-5 gears running 3.42s.

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What speed were you running in 6th (and I assume same speed in 5th)?

I can tell you for FACT the 4:10's do NOT get better mileage than the 3:42's

Ram3500Dually said:

I can tell you for FACT the 4:10's do NOT get better mileage than the 3:42's

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Aww, c'mon, Carl - it's not like you to be so ambivalent about this issue... :rof

There is only ONE way. That would be if you drive at the perfect speed for the 4.10's, and that speed is bad for the 3.42.

Tell you what. Take that up to 75 on the freeway, and compare then!

I bet you were going pretty slow. I note you failed to give the mph.

I was going 70mph (the max speed I'd travel pulling a heavy trailer).

At 73 MPH in my 2010 with 3.42's I was running 1625 on the tach and would get 18 on the highway. In my 2013 with 4.10's at 73 MPH I am running 2300 on the tach and getting 15.


Remember, thats 14 MPG by the EVIC which worked out to 12 hand calculated.

Very interesting - I'll be following this one, if anybody else can do similar tests...

Maybe, when I get my new axle, it'll be a 3.42 ratio, instead of a 3.73. Then, I can log my mileage under essentially the exact same conditions over several tanks of fuel. Then do the same when I get the 3.73's I originally ordered. I'd be the first person ever to log MPGs with the same driver in the same truck under the exact same conditions, with the only major variable being the gear ratio.

(But seriously, I will be able to do that to compare between 4.10's and 3.73's. Eventually. Hopefully. And I'm going to be very interested in seeing the results of that, too.)

Ram3500Dually said:

At 73 MPH in my 2010 with 3.42's I was running 1625 on the tach and would get 18 on the highway. In my 2013 with 4.10's at 73 MPH I am running 2300 on the tach and getting 15.

4:10 gears - YouTube

Remember, thats 14 MPG by the EVIC which worked out to 12 hand calculated.

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The variable here is two different trucks, emmisions, etc. Not really a fair comparison.

I'm going to run a test over a 10 mile stretch over the same road with cruise and get back with the results.

Can ya tell I'm bored! :rof

Two different trucks of the EXACT same specs. Both 2x duallies with the same options so weight, areo and everything else is the same. With the NEW emission systems in the 2013 everyone is getting better mileage than the earlier versions so if this was a 2010 verses 2010 or a 2013 verses 2013 then the numbers would even be bigger in difference.

NDanecker said:

I ran on flat ground in 6th and EVIC showed 17mpg. Switching down to 5th EVIC jumped to 22 and 23mpg --- same speed.

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Im not surprised by your findings, but try it again at 65 or 70mph. im guessing you were at a lower speed when you ran this test.

over all, it depends on your setup and driving style. If you have bigger tires or towing alot, i would put money on the 410 getting better mileage (overall) then the 342s completing the same task. If the truck is stock tires and maybe up to 35s and not towing, my money is on the 342s all the way.

think about this, remember back as a kid riding a bike and trying to climb a hill on a 10speed bike when it was in a higher gear? sucked! click, click, click down a few gear and you were able to expell less energy to climb the incline.

It all about the load on the motor and gearing.

ranchertx said:

Something is messed up, when I go to fifth at hwy speeds my Mpg drops 2 mpg

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Ours seems to be closer to 3 less mpg's dropping down.

NDanecker said:

I'm going to run a test over a 10 mile stretch over the same road with cruise and get back with the results.

Can ya tell I'm bored! :rof

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That's what I'm waiting for... Data - let's have some more data!

Too many people are looking at the EVIC for fuel calculations. Impossible to hand calculate mileage while driving at a certain speed over a 10 mile stretch. Hand calculate over a few tanks of fuel, the EVIC is only a guesstimate, and a feel good meter.

My 07.5 with 4.10's got 15-16 at 70mph turning about 1850rpm on 285/75/17's. The 2013 with 3.42's is getting 20-ish at 70mph turning 1500rpm on the stock 275/70/18's. Both with the 68RFE in 6th gear.