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2.5L upgrade info?

22K views 40 replies 13 participants last post by  Cory97TJ 
#1 ·
Looking for info on the 2.5l 1997 Jeep Tj engine

i have a cracked header and it has 141000 miles on it

somekinda performance exhuast is on it


what are the best ways to get performance of my 2.5l to be a little more


i can barely go 65 on highway with 31's

and i wheel with a 2.5l with upgrades that i think could easily go 95 on highway if he wanted it to


seems my 5th gear is worthless


anything that would add 10-30 HP is all im really looking for
 
#5 ·
short of forced induction, there is nothing that will give you 20-30 more HP on the 2.5
before looking to add more power, make sure it is already running right. a good tune up, etc will do lots for any vehicle that is running rough. if you are having issues making power, there could be other things wrong. a clogged up catalytic converter can cause issues, there are several things you should look at before you think about bolting on a bunch of "go fast" mods. most of which will be useless any ways.
 
#8 ·
I have a buddy with an all-stock 2.5L TJ that will top 100 mph. pretty easily. I don't recommend it, but I've seen him do it.

Ironic, isn't it? Whomever installed headers, trick exhaust, big tires, stickers, tint, fuel magnets, etc. probably insisted that it was an improvement.

2.5's are not asphault-ripping terrors in any form. It probably ran a lot better before the original equipment was removed.
 
#11 ·
Simple way to get more power out of it.. sell it and get a 6cly. 505performance has a turbo that will get you @170hp, but it close to 4k cost.
 
#12 ·
I agree with most everyone here. I have a 2.5 and I'm fine with it.....70 on the freeway is okay with me....I like to take in the scenery. But if you want more ponies jack up the radiator cap and slide a HEMI under there.......or maybe nitrous (can the 2.5 handle nitrous?) Or sell it and get a 6 cyl.
 
#13 ·
it take me everything my jeep has to get to 65, if i hit a hill im down to 55 or less, cant sell it and get a inline 6 i'd rather pull it and make it better

im not looking for a 240sx, just my jeep to be able to get the **** up and move when i need it too
 
#15 ·
give it a good tune up, wouldnt hurt to run some of that fuel injector cleaner/tank stabilizer stuff through either. see how it runs after that. if its still sluggish, pull the catalytic converter out(there is a way to check and get an idea if its clogged, i just dont remember how) if its clogged up, replace it.
and if your header is cracked, it might be a good idea to either fix or replace it.

as far as a tune up goes, you can buy tune up kits, or buy each part separately. just depends on how you wana do it.
another thing to look at is performance catalytic converters. how ever this is not for a performance gain, in some cases they are just cheaper then a stock replacement.
 
#22 ·
Ok, believ it or not, fix your exhaust leak. I have seen the 2.5 have huge power robbed by seeming minor exhaust leaks. Do some searches and you should see it.
Also, 4.10 is NOT enough gear for a2.5 with 31s. Remember, the 2.5 is no champ on the highway with stock tires that were 4" smaller. 4.10s are manageable, but you should expect a significant performance drop.
The 4cyl is fine in he trails because you use the low range, but on the highway you are underpowered.
 
#28 ·
if they were that incredibly unreliable, then the majority of new cars wouldnt come with them from the factory. its just one of those situations where you get what you pay for, if you buy a cheapo knock off fan, then chances are very good that it will perform poorly. lots of people seem to be happy running electric fans. you just dont hear about it like you do the horror stories
 
#29 ·
i was wondering really if

Headers were better then a new exhuast manifold

if i should throttle body spacer on it for a few mroe HP if not more response time
if i should put a cold air intake on it just b/c the stock box is crappy ( there is no way i can beleive that a air intake that is open is worse then stock box)

if my engine is slugged up is there any way to help with that

i put ALOT of miles on my jeep

and from my undersstanding my acceleration is slwo b.c of my gears not b/c of the engine
 
#30 ·
as far as headers go, its kind of a waste of money. just find a good replacement.

skip the throttle body spacer, it will do nothing but sit there and remind you that you threw money down the drain.

keep the stock air box. the cold air intakes you are thinking of are not actually cold air intakes. in the ricer world they are called short ram intakes(or something like that, been a while since ive been there) another issue with those intakes is they dont deal with dust as well as the stock on. you run a higher chance of pulling in things you dont want in the engine. just because you have a bigger opening for air to get to the throttle body, does not mean you can use that. all the info i have found points to the jeep stock intake flowing all the air a stock engine needs.

as far as a sluggish engine. TUNE UP! inspect and replace the cat if necessary and check the o2 sensors, etc. make sure its all running right before you go dumping money products that will not give you the results you want.

while 31s are bigger then stock, the 4.10s you have stock are about as good a gear as it gets. 4.56s might be nicer, but is it worth the roughly $1000 to put those gears in?
 
#31 ·
well im not regearin a D35 for sure ... , and love the info you just gave me

if my cat was clogged, would my O2 senor trip my check engine light? cause its not on and it passed inspection not long ago

tune up it is!
do i need a fuel filter?

i cant afford to do a fuel pump for sure

and i drive pizza's so i use lucas fuel treatment every 2 weeks or so

750 miles a week or so

now the question is , is "performance " plugs like the new g3 or w/es any better then normal ones? more spark = more repsonse time?
 
#34 ·
2.5L will never be a powerhouse, no matter what you throw on, in or at it.
Regearing will help you, but don't expect miracles.
Stay away from those 'Gimmick' plugs....
 
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