Gonna be graduating this year and gonna take off to college next fall so im gonna be traveling about 275 miles back and forth from home to college every now and then, therefore there will be Alot of highway driving. My question is how can i help keep RPMs down with a C6 trans no overdrive???? Im gonna be driving about 70mph. Also by then my truck will have a 6 inch lift and 35 inch tires with 4.56 gears in the back. My truck doesnt have a rpm gauge so im gonna buy an aftermarket gauge

 

C6 is a problem right off the bat. On top of that, your speed. Youd be a lot better off doing about 55mph instead of 70.

Bigger tires wont help matters either.

Transmission gearing, speed control (as in proper driving), and rear end gearing with the proper rubber are the big things to keep RPM down and mileage up. That goes with any vehicles.

To get by this issue they started making 4 speed transmissions.. (The E40D is an electronic overdrive C6) and nowadays we're up to 8 speeds (In Chryslers) which helps create more gear ratios with lower RPM ranges thus increasing economy.

 

Honestly, I would say park it at home and find yourself a little 4 banger. I went through college for electrical engineer. Kraft dinner and hotdogs and lasagna and pizza were the norm. Hardly had anything left over for gas. But I still kept it. It's still half way around the country but I use it when I visit the folks.

 

If you have to keep your truck I would put off the lift and big wheels tll had another vehicle to drive. Then swap in a overdrive transmission and slow down to 60mph the MPG difference by showing down only 10mph is astonishing, for my truck its about 3 or 4 MPG boost just by slowing down. But I get it sometimes you just have to keep that big truck. I will say for me my while I was in college my vehicle sat in a parking lot all of college and no one was real concerned about who had the coolest car just who had one.

 

A jacked up pickup will not get good gas milage no matter what you do, so either suck it up and pay the price at the pump or do what the other guys suggested and buy a little 4-cyl beater car that will easily get 3-4 times better fuel milage.

 

Park the truck, by a Corrola or Prizm (same car) We had a prizm that only ran on three cylinders most of the time and still got 30mpg. We beat the hell out that little car too. My wife drove it to college in Steubenville, OH from Oak Harbor, OH (about a 200ish mile trip one way) ever other weekend for two years. We put somewhere in the neighborhood of 300k miles on in the time we owned it. The best part. When it was new it got over 40mpg WITH a 3 speed automatic trans.

 

Ya i have to keep my truck i love it to death and when i lift it im just gonna love it more haha.

 

I give you props for that cause i probably couldnt do that. I love my truck and wherever i am it has to be with me haha. Plus i like road trips and road trips in a lifted truck sound pretty fun!

 

How much in price are we talking if i wanted to swap out the C6 with the E40D or AOD? And 55mph is way to slow in texas, ill be getting passed by rigs

 

E4OD will be nothing but trouble. Plus you'll need a new engine computer because E4OD trucks had 1 computer that controlled the engine, and tranny.

Right now your 351 has a manual transmission computer, only for the engine, cause the C6 has no electronics.


And AOD was never available behind a 351 from the factory cause it's a rather weak tranny.



Your best bet would be a 5 speed, but even that involves more work.

 

Are there any modifications i can do to lower rpms? Im not sure what my rpm range right now is on the highway since my dash didnt come with one, but id imagine its at least at 3500 at high speeds

 

55 is even slow in Ohio... And that is usually the speed limit on the highways. Haha. And I learned to drive in Florida where the speeds are higher. I bit the bullet for my truck.

For the last 3 years I have been driving a 6 cyl Sebring and just recently switched to a 6 cyl Grand Prix. Both are in the upper 20's range for mileage. I still have the truck but at 9mpg I cant afford to drive it. I do on occasion to give it exercise and at get togethers where id rather drive my truck to show off a little. But yeah.... As a college student, you gotta do what you gotta do.

 

keeping the truck, and getting decent fuel econ. will be tough. how ever you could look at running higher (numerically lower gears) say 3.55 (stock) and installing a klune under drive system, i also think somewhere there is a bolt on over drive.... just a thought.

but the best option will be, as the other guys said, buy a beater 4cyl car, park the truck.

good luck

 

If your truck now has 3.55 gears then simply bolting on 35" tires will drop engine rpms at 70mph from roughly 2700rpm to 2300rpm... assuming the TC has no slip which may not be the case, so it may be more like 3000rpm down to 2500rpm. That's pretty good right there, as long as you recalibrate the speedo for the larger tires you should at least not lose any fuel milage on flat ground at constant speeds. The truck will burn more fuel in stop and go traffic because the larger/heavier tires take more energy to accelerate and your final drive ratio will be equivalent to 3.14 which is pretty bad for a heavy vehicle.

 

Keep your truck NOT lifted and add a zf5. You will go from 9-10mpg to 13-14mpg. If you lift it and add tires you will go back to 9-10mpg

Like EVERYONE has said, buy a 4 cyl beater