4.56 or 4.10 gears for MPG

[xsports33]

I already have 4.56 gears and i'm debating on installing some 4.10s to get better MPG. With the Radix (Supercharger) i have plenty of power so i'm not too concerned with loosing power off the line.

I'll be driving across the country, from San Diego to Chicago, about 6 times in the next year slowly moving into a new house. At least 2 of those times i'll be towing a boat or a trailer. Also, i average about 70% highway driving normally.

How much of an MPG increase do you think i'll gain going with the taller gears? You think its worth it?

 

[Hemi426]

Definitely worth it. I'd even drop to a 3.91.

 

[Chris142]

What kind of vehicle?

 

[JHZR2]

go with a 3.2x or a 2.7x if you want good MPG and have plenty of torque

 

[DieselTech]

What kind of vehicle? tire size? In diesel we usually see a litle difference in milage especially if towing or oversized tires. Honestly you may see a 2mpg difference unless your tires are large then it might hurt you to go down to a 4:10. The cost would take some time to recoupe

 

[L_Sludger]

I changed from a 4.3 to a 3.73 differential in a Supra Turbo before. Not only did it kill low-end response, but my gas mileage did not improve at all.
Not worth it in my experience.

 

[DieselTech]

Originally Posted By: L_Sludger
I changed from a 4.3 to a 3.73 differential in a Supra Turbo before. Not only did it kill low-end response, but my gas mileage did not improve at all.
Not worth it in my experience.


Yeah it really depends on the application. It's just real hard to justify it. It is really no help for a turbo'ed vehicle also. More revs usually means less boost, less boost equals less fuel

 

[xsports33]

sorry... totally forgot to list it. i thought i had it in my signature.

2006 Chevy Silverado 5.3L HO with a Radix Supercharger, 6in lift, 35" tires and currently 4.56 gears.

And because this is BITOG, i have Mobil 1 0w30 in the engine, Dex VI in the transmission, and RL Heavyshock proof in the rear diff, RP 75w-140 in the front diff.

 

[oliveoil]

Depends on the torque curve. Do the math.

 

[DieselTech]

Leave the 4:56 in it!!

 

[Chris142]

Originally Posted By: DieselTech
Leave the 4:56 in it!!
X2....Gearing it faster with those tires may actully reduce the MPG because it has to work harder to maintain speed. Work harder = throttle open wider and less engine vacuum.

 

[DieselTech]

Originally Posted By: Chris142
Originally Posted By: DieselTech
Leave the 4:56 in it!!
X2....Gearing it faster with those tires may actully reduce the MPG because it has to work harder to maintain speed. Work harder = throttle open wider and less engine vacuum.


Exactly

 

[xsports33]

using the charts online (4lo.com) and doing the math, at 65MPH and 4.56 gears my RPMs would be 2845. with 4.10s my RPMs would be 2565.

So would 300 RPM really make "that much" of a difference in MPG highway driving?

Right now sitting just below 3000, i'm right in my powerband and i can feel the truck always pulling harder. not really "coasting" if that makes sense. It's awesome for power, just not sure about MPG. and yes i know, you don't get a big [censored] truck, lift it, and throw a blower on it and expect good MPG. BUT, i'm trying to get it as best as i can with good power.

 

[DieselTech]

It will make such a small difference that it will just take the entire life of that truck to makeup the money it will cost for the swap. I know I charge 1350.00 for front and rears and that just for genuine gear stuff. Step up to Motives and Timkin bearing and your closer to 1600.00

 

[xsports33]

yeah, that's what i was thinking. it cost me about $2000 when i put in the 4.56s and locker.

it'd probably take me a while to make up the difference of $2000 in gas savings. But still, i do like the idea of getting better MPG

 

[DieselTech]

To be honest you may see a loss. Alot of that depends on driving habits. I wouldn't count on gaining MGP. Thats why I say if you do it woulds be so minimal your pocket wouldnt notice. Your not going to gain 2-3 MPG, you would be lucky with 1 if that and thats on the road. I know you wouldn't gain anything in town driving.

 

[Virtuoso]

Keep 'em. Don't fix was isn't broken.

I'd love to whip around in a truck like that.

 

[FL_Rob]

Keep what you have ,save the money for new tires after the move and fuel during it,and its easier on the trans anyway.

 

[LAGA]

I have a 2WD 07 Silverado, with the 6.0. I went from the stock 3.73 to a 4.10 gear and my MPG has gone up slightly. I do mostly city driving with the truck. It now gets up to power faster and with less pedal than before. Any highway driving i`ve done has been about the same as MPG goes.

 

[JHZR2]

I don't really get why dragracer-esque throttle response is such a big deal. Let's not forget the reason for wanting to change ratios - potentially 36k of xc moving.

I doubt that drag racing up mountains is key...