gas mileage vs. gears

[jcp123]

i've been thinking about swapping out my 2.73's for some 3.25's, but i'm worried that my gas mileage will drop a lil more than i want it to going tnto college, etc. it's a 302/c4, and right now cruises at 65 at 2100rpm; with 3.25's it should be ~2600, correct?
my mileage right now is pretty good, it's about 16 average (~12 city, ~22 freeway). with 3.25's, i know my freeway mileage is gonna suck, but i also know that the city mileage should get better. still, i don't think they would even out, would they? what's your guys' best guess about where my mileage should be?

 

[TurboDoctor]

Was gas at right now out there anyway, Last time I was in the bay area it was still running 1.82 in the concord/lafayete area and 2.00 or so in the san jose area.

 

[jcp123]

well i got 87 octane here in milpitas at $1.60 today...

 

[2bav8]

There have been two major items that have reduced my fuel milage in the last few years IMO. Having gone from 22 MPG on the freeway and 12 +/- in town, I see 16 on the freeway but still manage 12 in town. The first and what I assume killed my freeway milage is going from 3.50 gears to 4.11s. Second, I'm pretty sure that a dual plane intake is going to get better milage than a single plane. Lastely, the addition of 58 cubes isn't going to help milage either.

 

[jcp123]

so minus the extra cubes...and since i already have a dual plane...i shouldn't see a huge drop in my average mileage?

 

[2bav8]

Don't forget I have overdrive.

 

[jcp123]

yeah but did you have overdrive both before and after? i thought you did...

 

[1969mach1351]

I went from 3.25 to 3.50 gears and my gas milage went up in town. If you are driving alot on the freeway your milage will go down. If you are doing more in town your milage should go up since it will be easier for you engine to get your car moving.

 

[jcp123]

i know that much...i just need to know by about how much...right now i do 60/40 town/freeway, but i don't know how that's gonna be when i'm off to college. all's i need are some approximate numbers...

 

[jcp123]

anybody?? please?? i'll be your best friend!!

 

[2bav8]

I've always had overdrive.