getting better MPG and HP after lift

[435Mj]

can i put a super duper cool spoiler on too....that will help right? lol

 

[Jeepzter29]

WOW... yup i put a spoiler on my XJ that difference is amazing..... The most amazing thing is this sticker i put on my jeep it gave me soo much more HP!

 

[Chris01xj]

I just lifted my 01 a few months ago , and I have seen a mpg drop, think about it my speedo turns slower and so does the Odometer. I havent notice much mpg drop thought if I think about it. It was right about yours at stock to now I think I'm getting 14-16 it useto be 16-17. I hearing that I need to regear I dont want4.10's but I'm thinking about it. My power has dropped ( just takes abit longer to switch gears now (aw-4) ) Oh anyone else have a opinion on getting 3.9 gears if they exist? I they would be better for me because I drive 46 miles day for work. As you all know I have 3.55 now. 4.10 would be nice for performance but I need better mpg(2.79 is getting too high).

 

[casm]

think about it my speedo turns slower and so does the Odometer

This is something that bugs me... People will spend a couple of grand to lift their XJ, but won't spend $20 to replace the speedo drive gear at the same time. It takes virtually no effort to do this - and in all honesty, I probably spent longer ordering the part than putting it in.

I havent notice much mpg drop thought if I think about it. It was right about yours at stock to now I think I'm getting 14-16 it useto be 16-17.

I'm running fairly close to that with a 3" lift and 31" tires - 13-14 around town (previously 15-16), 22-23 highway (previously 24-25).

I hearing that I need to regear I dont want4.10's but I'm thinking about it. My power has dropped ( just takes abit longer to switch gears now (aw-4) )

It'll also hunt more on hills, and you'll probably notice the torque converter locking and unlocking more frequently. I personally don't miss the off-the-line power all that much, but overtaking's harder above about 60mph - not that I'm pushing it above 60 much right now with the front end in the shape it's in, but if I have to it's noticeably more of a stretch.

Oh anyone else have a opinion on getting 3.9 gears if they exist? I they would be better for me because I drive 46 miles day for work. As you all know I have 3.55 now. 4.10 would be nice for performance but I need better mpg(2.79 is getting too high).

Are 3.9-ratio gears even available for the D30/D35/8.25?

Bear in mind that you're only talking about a five percent difference in ratio between the 4.10 and 3.9 gears. 4.10 gears are available aftermarket and in junkyards (look for 4-cylinder XJs with manual transmissions), but I've never heard of a 3.9 gearset for the axles we've got.

 

[FUNKYTEE5]

The only 3.90's I've ever seen for XJ were for the 8.25. 3.73's and 4.10's are everywhere though.

 

[loggydoggy]

Any ideal of the cost of regearing to 4.10s? Driving 60 miles to work each day, gas is killng me, but love my XJ. 31s on a 2" lift. thanks

 

[troutman1100]

Have 91 XJ with 4" Rusty Lift...Added Cool air Intake,and Throddle Body spacer..When from 15 to 20 miles to gallon...Earl:repair:

 

[loggydoggy]

Glad to hear it Troutman, I've got Rusty's preformance upgade on order. I bought the works spacer, K&N air, and exhaust. Gas in California is at 3.20 a gallon this system should pay for itself in 10 months. Sooner if gas goes higher.

 

[flexinxj]

ive got a '89 4.0 5spd.(gotta love the puegot!) im running a 3" lift and 32's and i average 20mpg. i was getting between 15 and 17, until i put on a turbocity intake and gibson cat-back - nice difference in mileage and power. i know those auto. suck up more power and mileage than the 5spd. i installed a t/b spacer on a all stock 94 4.0 xj and didnt notice any difference at all