Jeep Horsepower

[Junkpile]

your 4 banger has less HP, BUT it has more low-end torque.

The 2.5l doesn't have any low-end torque. A 90s model 2.5 made max torque at 3,500rpm(sully's 4.2 makes max torque at 1,800rpm) and max HP at a little over 5,000. That's why they had the 4.11:1 diff ratios, they take less torque to turn over and they allow the engine to get up into the higher rpms faster where it makes power.
For example: A car like a 69 Camaro with a TH350 auto, and a 327cid smallblock and a 290 degree cam would run best with around a 3.90-4.11 rear gear. That same car with a 427cid bigblock and a 290 duration cam would run best with a 3.23-3.55 ratio. The same thing is true for the six versus the four in Jeeps. The six runs best with a slightly "tall" diff gear, while the four needs lower gears to let it get up in rpms where it likes to run.
launch that 2.5l at about 3,000 rpm and don't shift until 5,500rpm+. A hopped up 2.5l can drop some jaws when driven like it needs to be driven. :wink:
=========
thanks for the info on the FI redrooster, I'll give those guys a call when I'm ready.....hopefully by next winter.

 

[ah_too_bad]

the 2.5 runs 135 hp stock.... and my does do 85 on the freeway pushing 31's and 4:10's...

 

[Snitty]

A hopped up 2.5l can drop some jaws when driven like it needs to be driven.

but how long will that motor last if you drive it like that

 

[bryanjeep]

All you guys know I hate my stupid 4 cylinder :lol:

 

[laneiac]

The four banger is a great engine and can last forever. It is just a turd when compared to the six cylinder. With the right gears and t case that little four banger will crawl up a tree. the 4.10 and 4.11 are gear ratios.

 

[Sully]

The 4banger is a great motor.They just dont do it for me on the highway or to run larger tires.Offroad I am sure their is no real difference in power.I just couldnt run a 4 banger around here.I would be limited to only run 31's if I wanted to keep it as daily driver.Once you go bigger and the gearing gets lower.You can kiss highway driving goodbye.

 

[bryanjeep]

I beg to differ, my engine has only 101,000 miles on it and started going bad at 90,000. It has been driven easily also.

 

[mingez]

You get a bad burger every now and again at a fuddruckers, but it doesn't mean all of the 200,000 burgers they make that week are all bad too. Sometimes you get a turd. Or sometimes Timmy, a freshman in highschool training for his first job, made your burger.

 

[bryanjeep]

I guess so, but it really turned me off to liking Jeep motors.

 

[88Wrangles]

I'm right with you Brianjeep! While my engine has almost 200,000 miles, It has absolutely no torque. Every one might say the 2.5L has a lot of low-end torque, which is because it is an in-line engine, It really doesn't have the torque in the higher end where it is needed for on the road. And, they really don't even have that much low-end torque at all.

 

[Sully]

I kinda Hi-jacked this thread.Back to Horsepower for jeep motors!

 

[Bounty__Hunter]

The MPFI 2.5L has decent HP numbers for it's displacement, but it's very limited when it comes to torque at any rpm. This is where the I-6 shines, low end torque.

My 2.5L is hopped up some, and I have a hotter cam waiting to go in. I keep the RPM's up where it's a lot of fun, but it can also crawl and bounce off 0 rpm and keep on going. Maybe I'll get an inertia wheel someday and help make up for the large distance between power strokes on the 2.5L engine.

 

[TwistedCU]

Lift and Tires on a 2003 TJ

My YJ w/ the 2.5L on 32's (measured a little bigger squeezed on 7" wheels) would get 85 MPH done. A few mods and she got me to work on time when I overslept. Like Bounty said, it takes a while to get up to those high highway speeds, but she'd get there. Although many told me I would not be able to use 5th gear unless I re-geared, it worked fine. I never had any complaints about torque (although it had very little) because whenever I needed the low end, I used 4-low. Did I mention the near 20 mpg I got???
I will say that as much as I liked it, it will be hard to go back to a 4 banger after owning this 4.0L XJ. :wink: The XJ has got some hefty kahunas

Now that POS AX-5 transmission is another story... :x


Oh, and Lady - the whole horsepower/gear ratio/tire size thing is alot simpler than you think. check this out it may simplify things:
http://www.superlift.com/information/gearing_up.asp

 

[mingez]

little jeep went wheelin

Whitey was a 4 banger???

 

[LadyJeepFreak]

8) I knew I could count on ya'll to set me straight. Thanks for all the information, sorry to get sidetracked here. I understand the general idea of the statistics now and will bookmark these links for later reading.

Lady :wink:

 

[siminsez01]

89 yj starting troubles

Lady, i'm looking at the same configuration you have .... (TJ) 31 Kumho MT's on the way ready to be mounted and balanced on my rock crawlers and a 2" Rubicon Express spring spacer lift. What do you think? How's it working for you on and offroad?

On another note, in response to the whole 4 banger thread that this turned into:
Doing 85 on the highway is quite a feat. I usually crowd the right lane and the uphill drive to the White Mountains in New Hampshire from Boston is unbearable(especially when there is more than a 5 mph wind....did i say 5, i meant 2).
I was looking at some threads tho and decided to get a K&N filter. Quite an improvement. I can feel the increase in torque.

 

[TwistedCU]

Whitey was a 4 banger???

yup, and with stock manual steering. parallel parking her with 32's was not an easy task.

Here's a question related to the original topic - how much HP does the 4.0L have in my '00 XJ?

 

[Junkpile]

I think it's got 195hp.

 

[Sully]

I think it's 190.At least thats what the TJ's are stock.Maybe they are tuned differently?

 

[Junkpile]

I don't know about now, but the XJ 4.0 was always rated like 5 or 10 hp more than the YJ/TJ 4.0

I think the only difference is the exhaust manifold.