gearing down...

[ottexj2000]

tjhawk- thanks for the info. My XJ is a 2000 so I have the 2 cats right at the manifold.

wheeling365- I havent changed the speedo gear but I am going by my GPS.

 

[nelson7172]

I have this 4.56 with 31 combo and love the power around town and on the trail. Gets good mpg around town but not so good on the hwy. At 70 mph according to my gps it runs at 2600 rpm and the speedo reads 82 mph. Just keep in mind that the driveline is spinning faster so you may have to fine tune pinion angles to keep the vibes down.

 

[92tahoexj]

would you get better highway mpg's w/ 32's and 4.56's ?

 

[lazyxj]

123

 

[clean4drxj]

What am I doing wrong, I just swapped in a 4.10s and rear detroit and get worse mileage on the highway. I might have to go 4.56.

Another contributor to worse mileage is the fact that CT has Lousey gas as compared to say.. NY or NJ, Also you might want to start thing about changing your 02's, even though they don't throw a code it doesn't mean that they're not in bad condition.