Ok I've recently had my 3vze rebuilt bored 40 over new pistons etc etc... Before the engine was blown my dad said it was getting about 22 miles a gallon or around there keep in mind this is an automatic and I'm running 33's and I now have about 2000 miles on the engine and I'm only getting about 11-12 mpg's now.. My dad bought Bosch spark plugs which I think may be one cause of it but any ideas on what would drastically decrease it like this after a rebuild I thought a rebuild would equal better gas mileage !!!

 

Its a 4x4 right? First off it was never getting 22 mpg. Maybe 18 at best. And even thats a stretch. With stock gears and 33's 12mpg sounds aboot right. Only real fix for that is gears. Go to a 4.56 or 4.88 gear set and you should be getting atleast 16mpg.

I went threw this process with my 89 4wd 3.0. After installing 33'' tires the mpg and power dropped a ton. I went from 4.11 to 4.88 gears and was getting around 17mpg and gained lots of power. Theres no amount of engine mods that can substitute for the correct gear ratio.

edit: yours being an auto, youll want to gear it even lower. 4.88 or even 5.29 gears, depending on your driving.

 

That's what I thought man I appreciate the info I'll prob go with 4.88's what's ur rpm at 65 tho? Just curious if you don't mind!

 

22mpg on a 3vze ahaha thats a good one... if your running 33's with a auto id get 529s

 

Well I still want I get decent power with decent gas mileage and I'm not the person that likes to run real high Rpms at high speeds ATM I run 2300 at 65 mph I'd like to keep it around there and get my mileage back tho if you know what I mean I wouldn't wanna run 3000-up at 65 so would 4.88's be what I want with an auto or 4.56's??! Any ideas !

 

http://www.grimmjeeper.com/gears.html

Punch in your numbers in this ratio calc.

But basically youd be 2450rpms @ 70mph with 4.88's

Id almost go 5.29's if I were you.
Then you'd be 2675rpms @ 70mph.

 

x2 on runs-on-4 said. you want to go lower then 4.56 being an auto. auto needs lower gears then the manual transmission does. so either 4.88 or 5.29 gears. either of those will bring your power and mileage back up.

 

Thanks guys anymore input would be appreciated it just seemed like to me that 5.29's would be over kill! But I guess not it would just equal more power guess I could squeal the tires better than now huh?