Four angry squirrels, or the TJ 2.5's and 2.4's

StG58

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Orygun, the wet side...
There are lots of questions that come up from time to time on how to get more out of your TJ four banger. The short answer is: You really can't. The fours are what they are. Now before you head down to the local store to get a "for sale by owner" sign, let's consider what the four does well and what it doesn't do well.

First off, the fours are stone cold reliable. Properly maintained, they will outlast the rest of the drive train and body. 200,000 miles is easily achievable with normal maintenance. The fours are hammer simple. There just isn't a lot of moving parts in the four to go bad. The parts that do go bad are easy to change out and cheap to purchase. For that matter, a whole good used engine is easy to obtain and easy to swap out.

The fours have either 120 HP for the 2.5 or 140 HP for the 2.4 TJ engines. That is the power budget we have to work with. There is really nothing that you can do to either engine that will give you more power without messing up where the power band is or that doesn't cost more than it's worth. Even if you could get more power out of the fours, the next issue you would have to face is the transmissions that are hung on the back. You will scatter parts all over a trail with more HP under your right foot.

Now what does the four banger offer? The SE's are a thinking mans Jeep. They are small and light. They are simple, with few options to fail over time. They are easy to work on. The axles, Dana 30 and 35's, are perfectly adequate for the fours with a little upgrading. The transfer case is way stronger than it needs to be, so don't worry about that. The transmission is barely adequate, but it does work if used with a little discretion. It'll last a long, long time if you don't hammer on it.

When you go to modify your four cylinder TJ, don't start dreaming of 35" MT tires and huge lifts, body armor, meaty bumpers and huge winches. Just don't go there with the fours. Think 33" tires, with 32's being better and 31's being best. Think 1 to 2" of suspension lift and no more than 1 1/4" of body lift. Think light weight and simplicity everywhere.

More later...
 
The 2.5 SE's come with 4.10 / 4.11 gears. That works OK with tires no larger than 31 x 10.50's, but you really need to think of putting 4.56 or 4.88 gears in if you do much off road. You can get 5.13's as well, but I'm not convinced that is necessary or desirable. The issue with gears is the interaction between the engine, the transmission, the transfer case and tire size. With the 4.10 gears, you end up going into low range more often than you really need to. On trails where you don't need to use four wheel drive, but do need to move slowly, the four just doesn't have enough power with the stock gears to go up steep grades at idle or just off idle. 4.56 or 4.88 gears helps a lot there. I've come to the conclusion that 4.88's and 31 x 10.50 tires are the best match for what I do and the SE's 2.5 liter engine. I'll put upgraded axle shafts in and lockers when I do the gears. The 2.5 works great with the stock axles, there's really no need to go for the Dana 44's.
 
Weight. Have I mentioned weight? We don't have a huge HP or torque budget to work with, and the power available at idle or just off idle is pathetic. It's very easy to put a 1,000 pounds of crap on a TJ in an effort to look cool and keep up with the Jones's. If you want to do that, you don't want the four banger. Be very conscious of how much weight you add to your TJ SE either through the stuff you bolt on or the stuff you throw in the back. Ten pounds here and ten pounds there adds up rather quickly. Loaded for the trail, my SE crosses the scale at 3,200 - 3,300 pounds with a full tank of gas and my fat ass out of the Jeep. I work diligently to keep the weight there, or even less if I can swing it. Think like a backpacker, not like an RV'er. Ditch the hard top if you can get away with it. Take your MRE's out of the box and saw the handle off of your toothbrush. You get the idea.

A note on aluminum parts. Just because a part is made out of aluminum, don't assume that it is lighter weight than the same part in steel. That is very often NOT the case. Be a pest and check with the manufacturer. If they can't or won't tell you what a part weighs, even approximately, look elsewhere.
 
Driving the TJ SE. The four bangers like a little RPM to work with. With stock gears and 31" tires, my SE likes to idle down a hard surfaced flat road at about 2,200 RPM. It's happy there. Accelerating goes best starting about 2,500 RPM and a good shift point is 3,500 RPM. Don't be afraid to shift down. In fact, when in doubt, downshift. On some hills on the freeway, I'll be in third gear doing the speed limit. Depending on how loaded down the Jeep is, that is. You're not going to hurt the four banger by running it at higher RPM's than you're used to. Go for it!
 
This post. I will reference this very frequently.! Thank you!!! I wish I could get rid of my hard top, these winters though don't allow it. A soft top in -10 going through a car wash would crack the frozen plastic windows hah.


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This post. I will reference this very frequently.! Thank you!!! I wish I could get rid of my hard top, these winters though don't allow it. A soft top in -10 going through a car wash would crack the frozen plastic windows hah.


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You're welcome. I hope this helps a lot of four banger drivers...
 
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Off roading an SE. The four bangers off road just like any other TJ, with some points to consider. We've built our SE small and light right? The implications of that are you are not going to go through or over stuff that the bigger TJ's can. This is where the thinking mans TJ comes in. Get down in the gears. Don't be afraid of low range. Keep the RPM's up. Pick your lines with care and drive around stuff, rather than over or through. Use your winch for steep or really rough terrain. Using proper caution, don't be afraid of dodging between trees and rocks, or going under stuff. The beauty of a small and light build is that you can go places that bigger rigs physically can't. Let you're suspension and tires do their jobs. Finesse your way through obstacles rather than using brute force. The up side of this is you won't break nearly as much stuff as the brute force crowd. With an upgraded SE and the proper attitude, the SE is as capable and reliable as the day is long.
 
My 2.5 is great for what I use it for. Just Daily Driving and cruising in the Summer. In the winter it is amazing in 3 ft of snow while I drive right past all the stuck cars. I've even had a offer to trade a Camaro for my TJ, I'd never sell the little beast in a million years.
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The four-banger TJ is fine in the right environments. I've wheeled with four-bangers a lot and offroad, you can't tell the difference. The only place I wouldn't want to be driving a four-banger would be at 70 mph on a busy highway trying to keep up with traffic, especially if there was any kind of a grade.
 
Nice to see the SE's getting some love[emoji1] 175k on mine and still going strong. I don't wheel it either. Just top down and doors off in the summer and I know if it ever snows again (starting to believe that global warming thing) I know I can get wherever I need to. And yeah 31"'s are perfect. Look great and will handle pretty much everything u need.

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Driving the TJ SE. The four bangers like a little RPM to work with. With stock gears and 31" tires, my SE likes to idle down a hard surfaced flat road at about 2,200 RPM. It's happy there. Accelerating goes best starting about 2,500 RPM and a good shift point is 3,500 RPM. Don't be afraid to shift down. In fact, when in doubt, downshift. On some hills on the freeway, I'll be in third gear doing the speed limit. Depending on how loaded down the Jeep is, that is. You're not going to hurt the four banger by running it at higher RPM's than you're used to. Go for it!

So you're saying I'm shifting way too early at 2500-2700?
 
The four-banger TJ is fine in the right environments. I've wheeled with four-bangers a lot and offroad, you can't tell the difference. The only place I wouldn't want to be driving a four-banger would be at 70 mph on a busy highway trying to keep up with traffic, especially if there was any kind of a grade.
That made me chuckle, Jerry. I wouldn't drive an SE in San Francisco traffic on a bet! I'd get run over.

On the freeways around here, where the traffic isn't bad or moves slowly when it is, the SE does just fine. There's one hill going up to Government Camp on Mt. Hood that gives me fits, but it's only one place and I just stay in the right lane and out of peoples way.
 
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So you're saying I'm shifting way too early at 2500-2700?
Absolutely, there's no need to fear the rpms with the four banger or six banger engines. You're missing much of its performance by shifting at such a low rpm.
Yup, the HP and torque peak on the 2.5 is around 3,100 RPM or so. Carry a couple of hundred RPM over that and then shift. It should drop you back into the bottom of the usable part of the torque curve and let you accelerate or cruise nicely.