Hi everyone...just curious about the mods that can be made to net an increase in both speed and fuel mileage for the Great White Buffalo...1993
I-6 300 with fuel injection. Right now I do need a new fuel pump in the front tank so I'm thinking that once I get started with that, I might as well explore other options as well. Also...if this goes on another thread by all means move it but does anyone know of a rigid tonneau cover for the 8' bed that hinges up? Thanks. Rich.

 

What is the starting point as in what milage are you getting now? These trucks will never do any better than about 15mpg city but the I6 can get over 20mpg highway.. only downside is you pretty much gave to totally destroy all usefulness as a truck to get that.

 

Mileage is about 10mpg....a tad bit more...sometimes I'll go over 11 but usually between 10 and 11 as an average...as I've been reading and have experienced, I know they're not going to set any records for mpg's but I'd like to get more than what I'm getting now. More mpg's and better acceleration...not that I'm greedy or anything huh...just want it all...lol. Good news is I just put a tune up on it but...still need an O2 sensor as I pulled the codes a while ago and got that message.

 

10 or 11 is super low for an I6, the o2 sensor should help a decent amount, but theres prob something else that's causing your low mileage. A 300 in a truck with medium-low gearing should get around 15-17 easy, more with high gearing and a high OD gear

 

forgot to mention that my tires aren't the original/stock size...duh-oh...rims are 15" radius (I guess) and 10" wide...tires are 31 x 10.50 in back and 30 x 9.50 up front...never have reset the speedo to reflect that but from what I've read it wouldn't be off by much more than 5% anyway right?

 

Your rims are likely 15" diameter (15" radius would be 30" dia which would give you sidewalls that are only 1/4" high!).

I don't know what size your original tires were. If they were 235/75-15 (28.9" tall), your 31" rears are 7.3% bigger, so that's what your speedo is off by. That would make your 10-11 mpg actually be more like 11 - 12 (still dismal).

The wide tires don't affect your speedo or your gearing, but they do create more drag, so that'll hurt mileage some.

 

Where are you, I have a Rigid Tonneau that came off of my 92 F350 8 Foot Bed. if youre interested $50 and its yours