Topic: Neep some advice on how to add more HP to my 91 YJ

[Elvin]

Hello Y'all

I just bought a 91 Jeep Wrangler (YJ) with a 3 inch lift. It's a 2.5 4 banger. I don't have alot of cash. Is there any simple mods I could make to increase highway performance

Thanks Guy's

Sincrely,

Elvin

[ratherbejeeping]

Do the 4.0L throttle body

[Elvin]

I looked up the prices for the throttle body. It sounds like a good Mod.

You said I should get a 4.0L Throttle body, but they sell one for a 2.5 also. Could you let me know what you mean exactly

[StefanBidi]

Check the How-To section here!  There's a post in there that explains how to get a stock 4.0L throttle body and put it in the 2.5L.  It's a $70 mod, and helps out quite a bit.

[ilandtime]

Best Mod I did was to install 4.88 gears.

[trailblazer95]

Best Mod I did was to install 4.88 gears.

Ditto that...

[Jeffy]

Gearing will make the biggest difference but that will depend on what size tires you currently have.  Manual or Auto.  The 4.0L TB will give you a bit more low end but everything works better when you have the correct gearing.

[Bounty Hunter]

4.0L throttle body and spacer, along with an airtube and conical K&N filter gave the best performance upgrade for me.  Follow it up with a better exhaust and an electric fan.  Then an ignition upgrade like Performance Distributor's FirePower kit.

As far as gearing, it's not the salvation you may think.  My modded 2.5L with 33" tires and 4.10 gears will keep up with my buddies stock 2.5L engine'd jeep on 34" tires with 4.88 gears.  Of course he needs to be geared a little lower but the stock axles won't allow it.

[StefanBidi]

I don't know how big of a tire you're running, but I have 31" tires and stock gearing.  Honestly, I think they are perfect for each other and the mods I have.  Nothing big: 4.0L TB, TBS, cat-back... and I still can still idle through anything in 4L.  In my opinion, I'm right where stock is as far as power to the wheels go and I feel pretty comfortable with it.  Keep in mind I only spent $300 to be where I'm at compared to whatever it would have cost to set new gears in (I got quoted $1200 back a few years ago for 4.88 and a TruTrac in the rear).

[Craigs_YJ]

As far as gearing, it's not the salvation you may think.  My modded 2.5L with 33" tires and 4.10 gears will keep up with my buddies stock 2.5L engine'd jeep on 34" tires with 4.88 gears.  Of course he needs to be geared a little lower but the stock axles won't allow it.

I bet your buddy does at Idle what takes you a bit of throttle to climb obstacles.

4.88 gears are bar none the best mod I've made to my jeep, besides the 8.8. Climbing a rock with a couple friends, I crawled up it effortlessly(With AT's i may add), a buddy with a 4L and 3.07's (And BFG MT's) needed a lot more skinny peddle then me.

PS where did 5'th go for you :)

[ilandtime]

I have done them all like 4.0 throttle body, throttle body spacer, K&N intake. MSD coil & wires Pacesetter header, high flow cat and Kat back. I also have 4.88 gears and 31" tires. The gears by far were the best money spent. I now have 5th gear again. I bought my gears and had them install for under $700. I can take my jeep up to 75MPH with no problems. A little scary but I can if I want. My next upgrade is an adjustable crank shaft sensor for a little more timing and an electric fan. I don't think there is much more I can do to my little 4 banger. I also tow my Ski boat with it. It does good doing it but doesn't stop to good. It likes to push the YJ around a bit.

[trailblazer95]

if you're not going to do gears, I think you'll notice the biggest improvement from the electric fan.  I'm installing mine now.  The stock fan weighs 5lbs (checked it myself), just imagine how much HP you're using to spin that thing around.

[Craigs_YJ]

Sorry didn't know you had 4.88's  :D

I bet I can get up to 75Mph as well....... but i wouldn't attempt it, a jeep is scary enough at 60!!

I agree with the Fan thing, I've heard its a really good mod. Another option, if your a backyard builder, is to buy another used 2.5, and mod it, like do your own porting and polishing, add a performance cam, and oversized pistons and the like, do it on your own time, at a leisurly pace, that way when your 2.5 throwns the bucket, you've got one ready to go in her with a lot more power. Repeate the process on the blown 2.5 and your set.

[Jeffy]

Sorry didn't know you had 4.88's  :D

I bet I can get up to 75Mph as well....... but i wouldn't attempt it, a jeep is scary enough at 60!!

Hmm, I've taken my Jeep up to 80mph.  It only gets scary if you keep your eye's open. :wink:

[lutzke21]

Having had 33's for a while (still stock, engine to axles...) I'd tend to forget how far off my speedo and odo were off...  On a recent long drive to Missouri, I clocked 80mph on my GPS.  Flat ground, little wind, and loaded with military gear and my mountain bike.

I was very impressed with that entire trip...I had just installed power steering (my manual box was shot) three days prior so I had another thing robbing power. Still averaged over 185 miles per tank (also per the GPS).  Still no 5th.... :?  Nice crack in the exaust manifold, catalytic is beyond the grave, and I have a hole in the muffler.  Guess that opens her up a little....

8.8 with 4.88 is in the works though....and the fan....and....and....and.....