Gas Mileage

[GranniesCaprice]

Whaazzaaaaaaaap???
Hey everyone,
I'm new to the Caprice world, so bear with me. I just inherited a 91 Caprice with a 305 and 41K miles on it from my grannie. I absolutely love the car. Right off the bat though it needed an alternator, battery, EBCM, right rear window regulator slide, updated CD player and speakers, two tires, and a radiator. The paint is severly delaminated due to the fact that she had it in North Carolina unstored for about 10 years and of course 80-early 90's GM paint sucks. All of the repairs only cost me $700! I'm a tech at a Chevy dealer, so all the labor was free of course and parts were at cost. However, I'm a young tech, and I'm not all that competent when it comes to '95 and newer cars(Prior to OBD II). I know the car gets a supposed 26 MPH highway (fueleconomy.gov) But I really wanted to try to raise it a little more. I was thinking of a high flow air filter, or a little more free flowing exhaust. Any suggestions? It has an Air pump, which I know is there to decrease emissions, but does it help or hinder Horsepower/MPG? and if so, whats the best way to plug the old holes?
Thanks

[silicon212]

If you disconnect the air pump, you will set a trouble code and a Service Engine Soon light which will set the computer into an operating mode that is not conducive for economy. So don't go pulling that stuff off.

Secondly, don't forget this is a big, heavy car with a V8 in it - you won't get the mileage much better than it is, now.

[HLandin]

silicon212 is right, economy is not primarily what these cars are built for. The reason your getting 27mpg instead of, lets say 20mpg, is because you have 305-cid instead of the fuelier 350-cid (which also give higher output as a result). If your really interested in getting better mpg, you probably should either consider a later model (265-cid L99 in 1994-1996 Caprice gets better milage than 305-cid L03 1989-1993 Caprice), or just another car. The Caprice was designed for comfort (due to its size), and of course, power.

The only real things that might increase mpg is an intake that flows more (example: K&N air filter) and the dual exhauts, but if these give you any gains, these will be minor (just like these modifications should give you slightly more power too).

Again, feel free to experiment but it is important to realize your potential limitations before you start so it doesn't lead to frustration or ultra high expectations.