Nightowl

I've taken my truck to the shop 6-7 times now for the poor fuel economy and after everything they have done I don't get much better fuel economy (around 12.5-13 mph). Other than that I love the truck. I'm thinking about several upgrades: DPF delete, power programmer, propane, and maybe the egr delete. Plus, I'm looking at an oil bypass like the fs-2500 or Amsoil. Also, looking at new gears. I'm thinking something around 4.55's. I really think the JUNK....I mean the wonderfully cleaning exhaust system is the real problem. I bet if I delete that beautiful system and put the upgrades on the truck I will get a lot better fuel economy...well as long as I keep my foot out of the go pedal!
Here is where I want you to post with what you have done and how it worked out. Please, no "I heard this works" posts. I need input from actual people with the upgrades.

xtoyz17

Why would you want 4.55? Do they even make them? I've heard of the new 3.42's which are supposed to help. Deleting the emissions stuff is supposedly good for another 3-5 mpg from all the reports I've read, and is actually supposed to HELP reliability of the new engines.

coreydr2003

I hear the DPF and a little tunning there getting alot better FM, like 3-6 mpgs more

jgiachino

My coworker bought the GDP Kit: http://www.glacierdieselpower.com/pr...id=07509EVC-CK

He really thought it was worth it.....i'll find out what he's seeing for mileage (i know he does it by hand)

Nightowl

Yeah, the 4.55 gears are to put bigger tires on the truck and keep the engine in the power band (I believe that is the ones they told me, it was in the 4.50's. I think Dodges are a little different like 4.55 gears instead of 4.56 gears like on the GMC's). Anything lower than the stock 3.73 and the truck will suffer a drastic power loss (feeling like it lost a ton of power but not actually loosing the power) and the engine will struggle causing the fuel mile to drop even further. I'm going to get the Smarty, put on a DPF delete kit, and put on an EGR blockoff plate. I'll be doing this in the about 3-4 weeks and I'll report what I find.

Fisherguy

4.55 IS way lower than 3.73, you've got it backwards.

What size tires are you going to, like bigger than 40's or something?
I've never heard of anyone going lower than 4.10's, you've got a diesel, you want to keep the revs down, if you're cruising on the highway with your revs over 2000 you're mileage will suck big time.

Most people with a stick like 35's with their 3.73's, what kinda tranny you have?

ozpall

4.50s gears and you are gonna be crawling on the expressways. what size tire are you planning on going to?

molalla1ton

agree. . . they are 4:56 and they are low @ 70 mph you are at 2000 rpm's maybe a little bit higher. . .37" tires. . . not far from stock rpm's

twoforme2

With the typical .7 OD ratio, and 37"tires
4.55's will net you about 1800RPMS at 60MPH
4.10's would be a little under 1600RPMS at 60MPH
3.73's would be around 1400RPMS at 60MPH

so if you do alot of highway driving the 4.55's might not be such a bad choice

Fisherguy

Where'd those figures come from?
I don't think OD on my 6 spd is .7

<EDIT>Just did a search, according to the following thread my 06 6spd has a .79 OD, the newer 6 spds (manuals) have a .74 OD.

I think the revs above are a lot lower than they would be with 456 gears.

Also found a handy link:
http://www.csgnetwork.com/multirpmcalc.html

06dodgedrw

rule of thumb i have always heard if you want to keep fuel milleage and not change top end speed they say 33's-3.73 35's-4.10 37-4.30 or 4.56 and the 4.88 or 5.13 for 40"+ my buddy had 4.10s with 37 and only got like 9-10mpg and i think his speedo was off and was 10mph lower than his speed, then we changed them out for 4.56's and the fuel milleage went to 14-15 and his rpm is fine forget the real numbers but its good no issues going 70-75 on the high way and the truck doesnt have to work as hard trying to spin them he ses its 10 times better with them.