Looking to gain some fuel efficiency. Have a '91 LX 5Speed (F22A1), and want to swap out the 5th gear for something that can help me pick up some gas mileage on the highway.

Any ideas? I blieve the engine is large enough to handle a failry significant change to a more conservative gear. I turn 3000 rpm at 80 mph, but I'd like 2500 if possible. Thanks for your help!

 

There are no gears you can swap to amount to that much of a change.
Your current 5th is .705, 91 LX trans.
To get a 100 rpm drop you can swap to the 91 EX 5th, .685
Anything else would require a custom gear ratio. For 2.5krpm you would need a ratio close to .575 or a lower Final drive which would also need to be custom (Which would affect how the car accelerates completely).

I would suggest looking into LRR tires.

 

Taller, skinnier, LRR tires. Pay attention to weight.

Look at ecomodder.com for more suggestions. There's lots of other things you can do to increase mileage other than a different 5th. I think the 98-02 5-speeds are geared a bit longer, too.

 

Stop cruising @ 80mph. These cars have a sweet spot for fuel efficiency and that's not it. If you want to save fuel try cruising @ 65-70mph.. That is usually the sweet spot. Besides that, there are no taller 5th gear sets than what are in the F series trans that I am aware of.

 

The 94-97 & 98-02 both share the same 5th gear (0.685) and final drive (4.062). The 94-97 Accord wagon has a final drive of 4.266 if you want to do any swap that would work.