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Improving Mileage on Lifted '99 XJ
- Thread starter xdarrows
- Start date
I have a new XJ. 2000 Auto 2" lift 30.5" tires and 3.73 gears. A recent road trip resulted in 17.4 to 18.3 MPG. I also run a 12 holes injector, 2.5" exhaust cat back. About 14-15 mpg on my commute of 15 miles. I did replace the cast iron exhaust manifold with a ceramic coated header, and put on a tail pipe. I'll see how that does.
LS swap it. You get 3-5 times the torque and horsepower and 50% increase in fuel economy.
My 01 with 35” tires 4.88 gears and a 3” lift got 13mpg at best, same rig with a 6.2 supercharged LS3 is consistently getting 18 on the highway.
I know an engine swap is a dramatic step to increase fuel economy but it is one of the many benefits.
Remember those 4.0s are basically 50 year old technology in a lot of ways. Designed when nobody really cared that much about fuel economy.
My 01 with 35” tires 4.88 gears and a 3” lift got 13mpg at best, same rig with a 6.2 supercharged LS3 is consistently getting 18 on the highway.
I know an engine swap is a dramatic step to increase fuel economy but it is one of the many benefits.
Remember those 4.0s are basically 50 year old technology in a lot of ways. Designed when nobody really cared that much about fuel economy.
- Location
- The Gump area
I wish I had LS3 money....I'm far too broke to do that engine although I am jealous of it slightly. but I have a 97 XJ that started life as 2wd and now is 4wd with help from a ZJ's 242 T case , drive shafts and front axle . I have 2" JKS rear shackles and front coil spacers on 30" tires and get 17.5 mpg average. 32o miles on 18 gallons with lots of town driving
An LS3 is total overkill. Super fun but not at all necessary and it actually causes a lot of problems.
An LS1 would be much more appropriate for an XJ.
Making a 2wd into 4wd is probably almost as much work as an engine swap. 17.5mpg is not bad at all for an XJ!
KarmaKannon
NAXJA Forum User
- Location
- Utahhhh
You aren't wrong. I think my stroker was getting around 16.5 when I managed to be very nice to it. I didn't drive it very much and maybe it would have gotten better though. We'll see what it makes when I finally get it back in the jeep. One of these days.
- Location
- The Gump area
But I have to drive like a old man all the time, keeping the revs under 2500 and starting off slow and keeping it at or near 60-65 mph with lots of coasting to keep getting that kind of mileage due to it is my daily driver at the moment. Still working on my ZJ to try and get it at daily status to put another 3" under the XJ and go at least 33's. XJ's just look better than ZJ's IMO.
After I lifted my XJ the MPG dropped?
denverd1
NAXJA Forum User
- Location
- Dallas, TX
cherokeecrawler
NAXJA Forum User
- Location
- Atlanta, GA
A buddy and I have 4wd swapped his '95. My father is in the process of LS swapping his TJ.
I can confirm that "4wd swappping" is much easier than a motor swap.
4wd swap takes a weekend. A nice looking LS swap takes a month if you're good at it.:cheers:
xdarrows
NAXJA Forum User
- Location
- North Carolina
old_man,
Where'd you source your stroker? I've been eyeing the Golen 4.6l motor.
https://golenengineservice.com/jeep-engines/jeep-4-point-6l-270hp-complete-stroker-engine/
Any feedback on what "extras" and accessories I can figure on budgeting for when I do the swap? I just put in brand new motor mounts, so I'm good there. Any lines that should be replaced, etc?
Thanks!
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