Work truck from virginia

[az_eric]

Been lurking for a while, but now that fuel prices are in the rise again I want to try to squeeze all I can out of this big ol truck.
I have a 2007 chevy 2500hd classic cclb 4x4 with 6.0 gas engine. I use this every day for work and getting 10-11 mpg. Looking to do some aero mods and learn to drive a little better and see if i can get closer to 15 mpg.
This is what I have to work with. Clearly not the most aerodynamic vehicle.

[freebeard]

How many miles at what speeds?

[az_eric]

Im assuming you mean miles driven per day. Roughly 100-150 miles a day. 65mph on the intersate. 50mph on the back country, and mixed if im in the city. Also i have about 93k miles on the truck.

[Stubby79]

With a big engine, I'd think gearing would have the biggest gains.

Then aero.

Then engine efficiency.

Then rolling resistance. (which is one of the easier things to deal with)

Then weight.

Finally accessories at the bottom of the list. Sure, they waste energy, but it's minor when compared to what it takes to keep a big engine spinning.

However you go about it, it will be interesting to see what gains you make where.

[az_eric]

Unfortunately gearing is not in the cards right now. Being a 4x4 id have to do both axles. I would like to drop drop down to maybe 3.73s from the 4.10s i have and swap the 4l80 for a 6 speed manual. But the cost of both those is a bit much for me currently.

[Vwbeamer]

Drop back from 65 to 62 mph.
Use this calculator, you will see that giving up a few minutes can give you a couple mpg. https://www.omnicalculator.com/everyday-life/speed

Another suggestion is to pump up your tires. I went from 32 psi to 42 psi on my truck and this helped a lot. Propably my best mod.

Also, is there a factory chin spoiler made for your truck? That could be worth .5 to 1 mpg at highway speeds.

[Vwbeamer]

using aero rolling resistance calculator

https://ecomodder.com/forum/tool-aer...resistance.php

used these variables I just guessed at_

Vehicle weight: 2721.6 kg / 6000 lbs
Crr: .011
Cd: .45
A: 3 m2 / 32 ft2
Fuel energy density (Wh/US gal.): 33557
Engine efficiency: .22
Drivetrain efficiency: .95
Parasitic overhead (Watts): 0
rho: 1.225 kg/m3

Dropping back from 65mph to 60 mph you mpg would go from 15.92 to 17.77
a gain of 1.85 mpg

Using the other calculator, on 30 mile long trip, you would give up 2 minutes and 18 seconds of time by driving slower.

So you have to decide is 1.85 mpg worth 2 minutes and 18 seconds of your time. It may not be, for others it is.

At $2.60 a gallon, the 30 mile trip would cost you about $7.10, at 65 mph and $6.00 at 60 mph. That roughly equal to 30 bucks an hour. Your time is more than likely worth more than that if you are working for yourself.

On my morning comute, I have 8.4 miles of highway. Dropping back to 60 from 65 only cost me 28 seconds, I decided it was worth it to get better MPG, even though this is just a hobby for me.

[az_eric]

Wow. I tried keeping it between 55 and 60 today and keeping it under 2000 rmps while accelerating. I already was down a 1/4 tank from this weekend but i guess we shall see if it helps. I know this thing is not very aero especially with my tool boxes and ladder rack. I guess leaving early will help out plus less traffic.

[cRiPpLe_rOoStEr]

Originally Posted by az_eric

Unfortunately gearing is not in the cards right now. Being a 4x4 id have to do both axles.

How often do you actually use 4WD? On a sidenote, even though it's not the best approach, I'm aware of some part-time 4WD vehicles which don't have the same gearing on both differentials, limiting the usage of 4WD for really slippy conditions and lower speeds on a safety and reliability concern.

I would like to drop drop down to maybe 3.73s from the 4.10s i have and swap the 4l80 for a 6 speed manual.

With a wider gear-spread for the transmission and a taller rear-end, it would be a good option. Not to mention manuals usually have a lower weight.

But the cost of both those is a bit much for me currently.

So I guess a Diesel swap is unfortunately also out of question too.

[az_eric]

I use 4x4 rarely. But, i work in rural areas often and the ground gets really nasty with rain. Ive been eye balling a kit to convert to manual locking hubs, but thats 2 grand.
Money is one aspect of gears and trans swap but the down time to convert to diesel most definitely isnt feasible. Pretty much have to make due until i get something else.