XJ vs KJ ?

[UNCC_99XJ]

I honestly tried, we ran the standard 101 course first year, had to redesign it [move rocks] for the KJ. Started taking KJ's on the basic trails at paragon, had to spend too much time hauling them off rocks, got to a point the guides started carrying floor jacks, had to again start moving rocks. If they ever get rid of those mother honking lower arms I might reconsider...

Well atleast you gave it a shot. Most of the people who bash the KJ for being a "cute-ute" or not a "real" Jeep have never even driven one and have no idea what they're talking about.

And I'll be the first to admit that the KJ does have some limits off road, and the lower arms tend to get in the way, but still, its alot more capeable than alot of other SUV's running around. And so far, it's prooven to be extremely reliable. My mom isn't exactly the easiest on her vehicles, and the KJ being her first non 4-cylinder, and its an auto, she feels the need to pretend she's in the indy 500 all the time, and its taken every bit of beating she's given it and just keeps going.

 

[raypla]

A friend of mine rented a KJ and we took it to a pretty tough trail and we beat the snot out of it. It took it, no serious rock crawling, but some pretty good mud holes.

 

[Flip94ta]

Its pretty simple why the KJ is faster, rated HP is derived from a formula that takes torque and divides by a number and theres your HP number. The 3.7L engine makes more torque than the 4.0L I know someone is calling BS right now but if you look a a dyno graph you see something like the 4.0 has 25 more ftlbs at 2000 rpm. That makes it torquer right? No because at say 5000 rpm the 3.7 is making 50 more ftlbs because the 4.0 is done. The 4.0 torque advantage wears out after the first 60 feet, for the remander of the "drag" race its power band will have less average power output than the 3.7L. Even with 600lbs less pounds to pull the 4.0 average numbers cant hang with the 3.7.

 

[Dr. Dyno]

Its pretty simple why the KJ is faster, rated HP is derived from a formula that takes torque and divides by a number and theres your HP number. The 3.7L engine makes more torque than the 4.0L I know someone is calling BS right now but if you look a a dyno graph you see something like the 4.0 has 25 more ftlbs at 2000 rpm. That makes it torquer right? No because at say 5000 rpm the 3.7 is making 50 more ftlbs because the 4.0 is done. The 4.0 torque advantage wears out after the first 60 feet, for the remander of the "drag" race its power band will have less average power output than the 3.7L. Even with 600lbs less pounds to pull the 4.0 average numbers cant hang with the 3.7.

Disagree. Even if you account for all that, the 4.0 XJ has a better torque/weight ratio than the 3.7 KJ from idle to 5000+rpm. The only advantage the 3.7 has is that it can rev up to 5800rpm as opposed to 5200rpm for the 4.0.
Oh, the 3.7 only has a 20lbft advantage (215lbft v 195lbft) over the 4.0 at 5000rpm, not 50lbft, and the 3.7 only starts to make more torque than the 4.0 from 3600rpm upwards. Below that, the 4.0 wins hands down.

 

[Cjmartz2k]

Its pretty simple why the KJ is faster, rated HP is derived from a formula that takes torque and divides by a number and theres your HP number. The 3.7L engine makes more torque than the 4.0L I know someone is calling BS right now but if you look a a dyno graph you see something like the 4.0 has 25 more ftlbs at 2000 rpm. That makes it torquer right? No because at say 5000 rpm the 3.7 is making 50 more ftlbs because the 4.0 is done. The 4.0 torque advantage wears out after the first 60 feet, for the remander of the "drag" race its power band will have less average power output than the 3.7L. Even with 600lbs less pounds to pull the 4.0 average numbers cant hang with the 3.7.

yeah, your wrong

 

[Pharaoh XJ]

They made them after '01 over there?

yes till the 1 quarter of 2002

 

[Flip94ta]

you guys got any dyno charts laying around? I'd like to see one. I am new to the jeep crowd and like to see what the do. I have been in a discussion similar to this where I thought the bigger engine was better and I was wrong. Specifically, when GM replaced the 350 with the 325. The newer motor kinda sucked at hauling, instead of towing up a hill at 2500 in 4th you have have to go up the hill in 3rd at 4000. I thought the 325 was a gutless motor, till they showed my dyno charts, after 3200 rpm the 5.3L smoked the old 5.7. In a drag race you are only below 3200 or 3600 rpm once in first gear. The KJ motor has peak torque at 4000, that and the fact the it revs to 5800 shows that it is the more powerful motor. It may not feel as torquey but it still makes more horsepower/high end torque, and thats why its faster.

Does that make it the better off-road vehicle? probably not. Atleast you dont have to wind out the 4.0l to make speed.

 

[Pharaoh XJ]

you have a point cause both were auto 4 spd but as mine shifted up @ 4500 the KJ was still going and at that point it was its power band (high end HP) so my low end power of the upper gear couldnt match that

 

[Dr. Dyno]

you guys got any dyno charts laying around?

Here ya go:

These will settle the argument about which is faster.

 

[Flip94ta]

Well he allready told us who was faster. :sunshine:

thanks for the charts, although the 94 cherokee was rated at 225ftlb vs 235 on the chart. The 3.7L still has the better top end and the early shift pint does nothing to help the cause. My final guess on why the KJ was faster, it has the tow package with 3.73's.