does anybody kno the gas miliage difference between 3.42 &3.73 on

[racinjace22]

I have an 09 sierra with 3.42 gears.. i just blew up my rear end and thinking about goin back in with 3.73 like i wanted from the start. I was wondering if anybody did this or knows how many mpg's i will loose

[Jsdirt]

I have 3.73's with the 5.3. I get about 15mpg around town to 17-18 on the highway if I go easy on it. My numbers might be a point or 2 lower than yours due to the ethanol content in the state of MA's gasoline.

[racinjace22]

thanks yeah i get like 18-19 at 75mpg i figured it would drop 1-3 but if it was more i was going back with the 3.42.. thanks this was big help

[TJay74]

I have a 2001 with the 5.3 and 3.73's and I get about 15.5-16.5 in the city and 18 on the higway as was just posted.

[kstruckcountry]

I make 18.5 on the highway with 3.73's. Dirt road to town and back I make 14-15. Not with a 6 speed but numbers should be comparable. I'd prolly make better town driving with the 6 speed.

[ajensen383]

Dont know the difference with the 6 spd, but I had a 2002 with 5.3 and 4spd w 3.73 and I just got a 2011 with the 6.2 and 3.73's, and I actually get better mileage with the 6.2 on the highway that I did with the 5.3...On average though I get about the same with the 2011, as i did with the 2002

[racinjace22]

yeah i didnt think it would make that big of a difference bc i had and 4 speed 5.3 with 373 and i would get about 16 and my friend had the same truck with 3.42 and got a lil better than me but i could pull the boat out the launch a hell of a lot better. i just didnt kno about these new trucks how it would act or if i would have to change anything else in the computer or anything when changing over to 3.73's

[Babyhauler]

Black Bear Performance can change your computer for the gears. High speed highway mileage will drop 1 or 2 as stated, but in town or city, stop & go traffic the 3.73's are about the same since it is easier to get the truck moving. Depends on your driving and what you want out of your truck.

 

Good luck,

 

Babyhauler

[Jsdirt]

Another thing to think about is if you have 4 wheel drive, you'll need to swap the front gears as well. Double the dough ...

[GPSilverado]

I went from a 3.42 to a 4.10 and only lost 1 mpg. In town really isn't much difference. I don't think you'll be unhappy with the change to 3.73's.

[cobrajet84]

How did you blow up your rear end?

[racinjace22]

babyhauler my friends tuned my truck with hp tunners im sure he can play with it to make it more efficient.

 

Jsdirt its just 2wd

 

GPSilverado thanks for the info.. what engine you have and 6 speed? bc man if thats the case i will do 4.10's

 

cobrajet84 idk i whip it around and stuff but it just went out i dog my truck im a speed person and like to cut up so i guess it just couldnt handle it..

[GPSilverado]

babyhauler my friends tuned my truck with hp tunners im sure he can play with it to make it more efficient.

 

Jsdirt its just 2wd

 

GPSilverado thanks for the info.. what engine you have and 6 speed? bc man if thats the case i will do 4.10's

 

cobrajet84 idk i whip it around and stuff but it just went out i dog my truck im a speed person and like to cut up so i guess it just couldnt handle it..

 

 

Mine is a 5.3 with a 4 spd. I am running stock size tires (275/55r20) which are 31.8 inches tall. If I try to run 80mph or so, I do lose about 2 mpg, which puts me about 16.5 to 17. At 70 I get about 18. In my around town driving, I can't tell that I lost any mileage. It varies from 15 - 16.5 around town.

 

With your 6 spd, you will have plenty of gear with the 3.73, although the 4.10's will not hurt much at all. If I had a 6 spd, I would go 3.73 if that helps. I tow a boat that weighs in about 6500 lbs, so that is why I wanted the lower gears.

[racinjace22]

yes thanks for everybodies in put i think imma go ahead with the 373's

[kstruckcountry]

You won't regret it