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uponone789 07-20-2013 09:06 PM

Performance mods on a 2.5 vs an engine swap??
So I finally finish a 9 month resto on a 97 TJ 2.5 - she has 95k miles and I did a complete much needed tune up - new everything except that catalytic converter. So the wife takes it out for a spin and complains about the performance - this is the only 4 cylinder anything we own. It has factory AC which will never get used. If I delete the AC, do under drive pulleys and an electric fan will this provide any real world performance difference? I'm thinking complete engine swap with something that has 8 cylinders. This is going to be a part time DD for her and that's it - never offroad. If some simple mods would give it more pep I'd rather go that route. Thoughts and opinions please and thanks.

Buz 1 07-20-2013 09:48 PM

there's really no "pepping it up".. i've got the same engine with 5 speed manual(approx 185k) & i love it. i bring a cord of firewood(roughly 4,000lbs + 1000lb trailer) out of the woods on every trip in,, & i just hauled a xj 30 miles up Interstate 75 @ 65mph on a 2,000lb car hauler. can't really ask 4 more than that! take ur shift points @ between 2500 & 3,000 rpm & they do just fine... JMOO

uponone789 07-20-2013 09:56 PM

I forgot a critical detail - its an automatic. I've been google searching after I posted and so far it looks like it would make more sense to just put the money toward a v8 swap instead of dropping $1000 on 20hp worth of upgrades.

uponone789 07-20-2013 10:32 PM

Ok I'm obsessing - I doubt this will get many looks anyway since there are so many of these threads on 2.5's. What about a cold air intake, electric fan, and a limited slip rear with 4.11's?

TeamFATBOY 07-20-2013 11:23 PM

Never off road? What tires and size are you planning on running?

uponone789 07-21-2013 07:04 AM

It has a stock sized set of goodyear wrangler radials - 235/75/15 I think. How do I tell what size diff's I have? I assume their D35's - how do I tell if I have a LSD rear? thanks

Big Cole 07-21-2013 07:26 AM

64 Attachment(s)
There are no cost effective mods for that engine. Save your money for an engine swap or just learn to live with the lack of HP.

Owen_TJ 07-21-2013 07:29 AM

You're not going to get any noticeable power from the 2.5 with mods...unless you or the p/o have changed or upgraded axles (which I highly doubt, especially with stock tires) then you've got a d30 front and d35 read. No you don't have LSD.

4.10s are stock on a manual 2.5L and work great for stock tires...I've got a 2.5 and have 4.88s in mine but I'm also running a lift, 35s, chromoly front shafts, and a ford 8.8 rear

WaterDR 07-21-2013 08:19 AM

If its a DD for her, then make it easy to drive and comfortable. You need AC...especially a gal. V8 swaps stink for other reasons and resale will suck.

Sell the jeep and buy one with a 4.0. Problem solved.

Owen_TJ 07-21-2013 08:28 AM

I think a 2.5 is great in town and offroad...only time it lacks is on the hwy

Owen_TJ 07-21-2013 08:41 AM

I forgot to clarify that you've got 4.10s stock only if it's manual...if it's auto you've got 3.73

uponone789 07-21-2013 12:09 PM

I do have an automatic - so would going to 4.10's with an lsd be the most logical mod?

WaterDR 07-21-2013 02:18 PM

It will help from a stop but be even worse on the highway. I think a gear swap will prove to just be a waste of time and money. Keep in mind, the cost is twice because you have two diffs to swap.

Anyone not happy with the 2.5 should not waste a dime on mods.

Just my very strong .02

uponone789 07-21-2013 02:25 PM

I think this is what I'm starting to realize - we have a Yukon xl that she drives and I got the jeep to have something smaller for her to commute in on nice days. I think I'll just leave it alone and see what happens.

TeamFATBOY 07-21-2013 10:11 PM

I have a 97' 2.5 and really like it "But" I also have a 5 speed. I've also done a bunch of stuff to mine like tires and gears plus some other stuff over the years. I personally have never liked auto's with 4 cyl's in anything, JMO. Mine was fine stock with no mods and 30x9.5 BFG AT tires and was fine on the highway and great around town even with the AC. Really, how fast are you planning on driving it? 70-80? it should do that stock without a problem. One thing I have noticed is that mine does like the higher RPM's and running steady around 2900-3000 RPM's. I don't know where you live but if you don't deal with snow or anything like the I wouldn't worry about a LSD. For just fun in the sun and road use, I'd keep it and drive the chit out of it!

Buz 1 07-21-2013 10:29 PM

no1 can tell u that the rear-end is not a lsd without lookin @ it.. look 4 a tab under 1 the pan bolts on the diff.. u can also get a free build sheet from crysler.. it will tell u...:)

Mortalis5509 07-21-2013 11:52 PM

If you are not offroading it then go with the 4.0. Dropping in a 5.3 or likes cost a decent bit and even more if you aren't doing the work. 4.0 (6cyl) is a great motor and goes on forever.

Matter fact I have a drop in 4.0 for sale. Not sure where you are but I am in GA. PM me if it's something you might want. I am not saying a 4.0 because I have it sale but it's a better set up for you since it will stay on the road. Really dont need the v8 power.

uponone789 07-22-2013 07:15 AM

I'm in VA - not too far. email me with what you have. I do live in an area that gets snow but other than taking it out just to play it won't be a primary driver in bad weather. I would like it to be a proficient as possible though. I'm going to have the catalytic converter replaced today - (the only thing left to replace) and see if that changes anything. The tune up helped drastically - below is a pic of the upstream o2 sensor that was replaced. The spark plugs were just as bad.

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