Been searching a bunch to find a list of mod to do to my 03. There seems to be all kinds of answers depending where you look. What I am looking for a list of mods from cheap to expensive that would be worth while to gain better fuel economy. I already get great mileage out of my truck but would like to strech that more if possible. Thanks for any help you guys can share.

 

look at whats in my sig, i can say that nothing has helped my mileage at all and i have the records to prove it from the day i bought my truck. i think i would have seen some gains had i not gone to bigger tires but then again i am still averaging around 16.5 for all driving conditions good luck and just keep it stock unless you want more power then bomb away. if you want to seem mileage calcs and results pm me and i will send an excel spread sheet of mileage tracking and results since add-ons

 

buddy of mine is putting down some pretty stout numbers on the highway

he's running a
2003 305/555 with nv5600 quad cab short bed 4x4
EMS hub kit
285/70R17 BFG AT's
3.42 gears. open differential front and rear (helped alot on long nevada trips rpm wise for him)
stock turbo though he is thinking about upgrading to the HE351 to see what changes.
AFE exhaust manifold (didnt change anything but helped rear cylinder temps a little)
Smarty 4.11 on level 3 though level 5 yeilded similar numbers
4" exhaust no cat since it didnt come with one
CFM+ intake (didnt change anything)
AFE air filter

he recently did a set of Don M's small milage injectors.

before the injectors he could consistantly pull down 20-21 mpg with 23-24 in rare cases. he now says 22-24 consistantly with a high on long central valley trips of 26.5 . hand calculated.

 

driving style modifications will help me more than anything. if i could stay under 75 mph on the interstates it would make a huge difference.
no mods to the truck yet, but i'll soon replace the 265 series tires with 285s, that may help some... the gears are 4:10.
i thought of ditching the cat too, regardless of any mileage increase (if any)

 

wow thats some bold #'s but with 342 gears it sounds believeable,, Question that is running empty right??? @ what speed???? ,,, NV5600??? is that a manual tranny,, excuse the newbie question

 

riverrat, the nv5600 is a manual trans so that top gear is kinda nice... not sure what the ratio is compared to the top gear of the auto but im sure its a bit higher to be more highway friendly...

 

I have the slushbox and it is an 03 so no cat. I think it may have helped a bit. I have been averaging 18.5-19.5 MPG hand calcs empty with mixed city/highway driving. I am learning to keep my foot out of it and under 75mph and that seems to help too. Just looking for other things that may be worth spending my hard earned cash on to gain some better mileage.

 

i have an 03 and get 18.5 to 21 hand calculated. i made my own intake horn and got 1mpg better legit i was amazed over it.

 

show us your horn, lol

No really I want to see it

 

I have an 06, QC SLT G56, 3500 4WD Dually 265/70R/17's 5"TB Exhaust,,,(How I bought it) when I first got it my best mixed light city/mostly Hwy hand calculated Mileage was 18.6,,, average city HWY mixed is around 15.5- 16.5,,, as said by others,,, trouble is keeping my foot out of it,,,, LOLOLOLOL!!!!!!

Have added TS Performance MP8/wMPD monitor Banks High ram intake/Banks cold air W/super scoop

Have thought about adding the stainless EXhaust manifold and the Banks intercooler if it would help me gain some MPG and lower My EGT's some more,,, Any thoughts???

now18.4 - 19.6 Mixed as above,,, and pure hwy running 65-70 have gotten 21.9

Towing the 15K race car hauler @ 60-65 gotten 11.5 12.6 MPG @ 70-75, 8.5 or - MPG

W/Stock trailer and a few momma cows@ around 10-11K have gotten 13.8-14.4

The High profile 44' carhauler needs a bigger truck!!!!!!!!!!! LOLOL!!!!!!

The 28' box low profile stock trailer or my Bullet Bass Boat is just right,,,,,

 

285/75R17 tires 60 pounds or more of air, synthetic oil, change the hubs to manual locking, a U S gear aux trans (an overdrive unit), better intake and exhaust. I get better mileage with my Edge J/A on drive mode than I do stock.

 

Yep I get better running empty mileage w/MP8 turned up & keeping the boost @ 7 lb or less by easing/sneaking up to 65-70,,,, but have to back it off for loaded/towing,,,,,same driving style yields the best mileage LOLOL!!!! (thats the hardest part,,, LOLOL!!!!! what model truck and Mileage??? is it dually or single wheel????

Where did you get Over drive unit??? about 2K?????

 

The best thing you can do to improveyour mileage figures are;
1- slow down,
2- use the cruise contol,
3- lift early and coast as much as you can (not in neutral, just under 40 mph your trans and convertor should unlock and let your rpm drop to under 900 rpm),
4- synthetics in everything with friction modifiers to lessen the drag, including the grease in the u-joints and bearings,
5- additive in the fuel to increase the cetane number and thus the power produced,
6- clean air filter,
7- low restriction air cleaner and different intake from stock to improve the flow into the engine, (see pic posted here of mine I made from 3" stainless.)
8- good inflation pressure on tires (mine are at 80 psi all the way around),
9- clean it, (dirt weighs pounds, pounds take fuel to haul down the road)
10- don't pack around a big tool box in back full of stuff you never need...
11- consider an American Overdrive unit for long haul flat ground that drops the RPM into the "sweet spot" where the BSFC is the lowest.

Just a few thoughts.

 

Great info cdennyb!

 

Tac's under the right foot....LOL Yours is an 03, The 305/555 motor gets the best mileage out of all of the common rail engines.