I originally had a K&N air filter and a flomaster muffler installed and it increased my gas mileage by 2 to 3 miles per gallon. However, I then installed a flomaster cold air intake system. It increased my horsepower, but decreased my gas mileage by about 2 miles to a gallon. I currently get 20 to 21 mpg.

I am considering a new catalytic converter (more free flowing) and larger exhaust system (2.5") all the way from the manifold back (not just the cat back). This is in hopes that the mpg will improve.

I drive between 70-80 mph on the highway and don't baby it in town. I also am running 40 psi in my tires, so inflation is not a problem. I am sure the larger tires and wheels decrease my mpg but I like the 255-50ZR-17's.

Before I invest in the exhaust system I just wanted to know your opinion as to whether or not this should increase the gas mileage.

Thanks for your help

 

tires dont help gas mileage at all, especially big. im not sure on the exhaust though.

 

there are alot of people on the forums that say they have gotten better gas mileage from an increase in tire size, and obviously others that say the bigger tires wreck their gas mileage. not sure what really determines which way it goes but, read around.

 

Until you change that, you aren't going to improve anything.

 

+1

 

I get better mileage at 70-85 because at 65 I have to use too much throttle to keep the truck at speed. 75mph at 30% throttle on a flat surface will get me 19.5 mpg.

 

+2

 

+3

i baby the hell out of my truck, the truck is about 99.9% stock, i have a K&N on my truck with the 5 speed, with 225/60/16's and i get anywhere between 26-31 MPG... driving style has alot to do with fuel economy, pick yourself up a scan gauge, and go from there

 

with the whole tire thing its not the size its the tread. if you put a wide diameter tire like 33's on it will help mileage if it is a normal street tread on the tire because you will go a little bit farther every time the axel turns once as compared to stock tires, do the math, but if you have like 35 inch mudterrains your going to have a lot more resistance from the tire because of the aggresive tread, plus the deeper lugs on the tire and the size itself just adds weight so its really up to you. tires similar to stock aren't bad for mileage but bigger is badass looking.

 

cai's most often lose you mpg because you always want to put your foot into it to hear that nice throaty hum and whistle the cai produces

 

Also.. dont count on speeds for highway driving as straight gas mileage wreckers.. its all in he RPM's.. the lower the RPM you can go to keep up the same amount of speed, the better your gas mileage.. not hammering the throttle or giving it more gas to get over a hill is the first step to getting real good gas mileage. If you drive aroudn town at 3000 RPM and slam the gas at every stoplight.. you wont ever get better gas mileage no matter what mods you put on it.

 

also load has alot to do with it. load meaning the amount of load you are putting the truck under....how deep your pedal is. Key for good mileage = driving habits.


you have a 4cyl...consider yourself already lucky.

 

i went to a 245/65/17 on a 17x9 forged wheel and got an increased (after corrected)

 

from personal exp just recently i slowed down and excelled slower too and i just bumped my mpg 3... instead of 240 a tank i get over 300.. and i have 4.0L.. just slow it down and if its stick stay in lower gears.. you will still have power.

 

Excellent! You could document that, and sell it! It will be more effective than all other "performance mods" for MPG!!!

 

I think mods are great for flow but we add mods for performance so anything that can help mpg can also hurt mpg based on driving habits.. sure if you drive like a grandma with mods you will love life.. if you drive like a teenager with mods your mgp will go down in fact..


thanks =] i was really suprised at how such small costless change could do so much.

 

hey now ima teen and i dont drive like a bat outta hell unless im trail riding lol

im not sur emy mpg is because i havent realy tryed checking it up i dirve over 60 miles a day with a 3.0l auto with 4.56's and 33's and i can make a tank last almost a week

and i have to refil on saturdays cuz friday i go buck wild and go everywere and i have to keep the pedal to the floor to keep up with my friends in their dang Z71's....

 

Z71 what???

 

scan gauge!

 

u dont need a gauge to know your driving like shizzz hahah