Topic: Help with basics and Performance.

[Colin]

For background, I have a 1993 YJ 2.5L with 31x10.50's and a 1 3/8" Body lift (A 3 inch BL cut in half with the proper bolts). No front sway bar or front track bar. Smittybuilt tube bumper in the front, and I have a tube bumper sitting in my garage for the rear as well.

Love the Jeep, and working slowly and collecting finances to build it a bit bigger now. My plan in the next year or so is to go with a 3.5" BDS lift, 33's (not sure yet if I want 10.50's or 12.50's) and some skid plating to go before all of that.

I live in Massachusetts and am a member of Baystate Jeepers.

I'm currently in the middle of adapting 1995 Saab 9000 Aero seats into my Jeep. I'll be posting up a write up as I do this, but they are excellent seats and I got them for free, so I'm going to be making use of them.

I'm also doing a CJ tailgate conversion, and just waiting on a decent tailgate now. I have pretty much everything planned out, and a fellow club member is doing a body swap on his CJ, and so I'm talking with him about getting one of the two tailgates he'll have.


Well now you have my Jeeping life story, here's my questions for you:

I'm trying to get the maximum performance out of my Jeep. Right now it struggles a bit on the highway, and I realize it probably always will unless I go with a bigger engine. Unfortunately for me, I didn't realize this when I bought it about a year ago the big difference between the 4.0 and 2.5.

Now with the fuel injectors, is the only way to do this with a proper sensor and then knowing your stuff with injectors?

I'm honestly not all that automotive... intelligent I guess is the term. I've learned a lot, and am learning a lot, but I haven't done much more than change my oil before I bought my Jeep. (But I'm really loving learning how to do all this.)

Now I've thought about doing an open air intake, throttle body replacement (with the 4.0) and an exhaust, but I'm not sure exactly if these will really make any big difference.

What I want to do is maintain my lower RPM torque, while gaining a bit of power at higher RPMs.

So can anyone help point me in the right direction. Explain it to me like I'm an idiot, because that's where I'm working from. Before I bought my Jeep I didn't know what a torx bolt was, and let me tell you, now I want to kick the Jeep fellow in the nuts who decided to put those in.

So any help would be great. I'm willing to learn, and willing to work on my Jeep. I just don't know what people actually have found that works well. Not just a little improvement, but well.

[chrisfranklin]

Bigger tires -- even 31s -- are going to tax the "displacement-challenged" 4banger.  Rather than focus on the engine, maybe you should look at regearing your axles. 

Course, when parts wear out on the engine -- exhaust manifold, exhaust, cat converter, ignition -- you can always put in the upgraded performance parts sold out there.  But a thousand bucks worth of that stuff is only going to buy you about 10hp for the 4banger; so less sting if you wait till the stock parts fail.

As for fixing what ain't broke:
An electric fan swap is reportedly a good move.  4.0TB swap is also good.


 

[jcoleman]

for real performance gains you would need a turbo or some other stroker upgrade. yjmechanic did some upgrades to his 2.5l that netted him about 190 hp.  I believe he did most of the work himself, and it cost him roughly 1500. Here's that thread: http://4bangerjp.com/forums/index.php?topic=314.0

Also just spend some time going through the old threads in both the mess hall and the work bench.  There is a ton of information in there that would be extremely useful.

[BOOGIE444]

Stick some 4.88 gears in there for your future 33" tires, that will give you your power back.  Stock gears + 4banger + 31" tires = DOG.

[gomi]

From my expierience, the most difficult part about working on your jeep is getting the guts to try. I think you'll find that once you get started, and with the right tools, its pretty fun and easy.

[Jeffy]

From my expierience, the most difficult part about working on your jeep is getting the guts to try. I think you'll find that once you get started, and with the right tools, its pretty fun and easy.

That's when you find someone who's not afraid of a sawzall help you... 

[YJmechanic]

sawsalls fix everything,  i did do a big build on my engine but that is pretty complex for someone that isn't very mechanical,  but just like what is said i built my motor cause i needed a new motor,  gears are the best way to go,  get a 8.8 rear axle then throw in some 488 and and you will be good with the 33's,  also i have the bds 3.5 and it is much larger than any body else's 4 kit.  i have the 3.5 springs with 1.25 shackles and i measured my flex for shocks and the shocks that fit were supposed to for a 6" lift.  easy and cheap though, you can get a 4.0 tb for 40 and 5.0 mustang injectors for about 30, and rusty's offroad makes an intake for 30 plus 30 for filter,  electric taurus fan for 30,  and you can put in a dynomax muffler for 30. maybe some bigger plug wires and hot coil.   those put together is less than 200 and you should get a little bump of power,  like was said review old threads,  and let me know if you need more help.

[Colin]

yeah I've thought a lot on regearing, though I guess my money situation has made me put that off. I really have been wanting the lift/tires first, and then going with an 8.8 swap so I won't waste my money regearing the 35 because I do plan on swapping it out in the future.

I haven't broken anything on it yet though (though I do need to replace U-joints) so if I don't for awhile, I may just put some more money into it.

But right now I'm having some issues actually getting over some of the things, and height/skids seems to be the most important.

I'm building up for off-roading, and when I can afford (in a couple years) to buy a DD vehicle (something that I can tow the Jeep with) I plan on going all out with it.

Right now I'm trying to find the good balance.

It sounds like the gearing is the big issue, and that everything else is just icing on the cake. Nice, but not a huge difference. (And I'd rather do an engine swap that put a supercharger on.)

[jcoleman]

(And I'd rather do an engine swap that put a supercharger on.)

Me too.  I was just saying that the only way to achieve significant power gains is to turbo or build it up like yjmechanic's jeep. 

[YJmechanic]

i built my motor because it was cheaper than buying and swapping motors,  and there wasn't all the conversion work involved in swapping.  height and skids are important but making it home is too,  and the 35 if not careful will leave you at the trail.  plus the 2.5 is fine with the gearing behind it.  unless you are going to something crazy like 37 and 60's you don't need a motor swap.

[cmgorman94]

The best thing you'll do to increase the power and driveability of your Jeep on and offroad is gears, especially if you go to 33's.  If I were you and I was just starting out with the Jeep I'd look at a few different approaches.  I would try a belly up skid, an 8.8 or D44 swap, gears and lockers, then a lift and bigger tires.  In that order.  The best mod you'll make on your Jeep is improving your driving skills.  A lot of people (and I've been guilty of this too) underestimate what a locked Jeep on 31s is capable of.  Sometimes I wish I still had 31s, some trails were a lot more fun that way. All of this is just my opinion.  Back to your question, I'd regear, you'll get way more power that way.  The mods YJmechanic mentioned will work great too, but once you step up in tire size you'll need to regear anyway.  Also, you could consider a snorkel instead of a aftermarket intake, what better cold air intake is there?
Chad