fishtaconc

like I stated earlier, a good 2.25" Mandrel bent exhaust will do a lot for torque. You can actually make more torque with 2" but itll suffer on the upper end. Most aftermarket companies that advertise their product will add 5hp more time than not just move the power up or down in the rpm band. Most mods are kinda useless after a point because of other components such as the cam in the 4.0.

N20jeep

...eh.....just spray it...


....worked for me

superj

torque wins races though. race a big ol 4 door ford diesel with a chip and injectors against any stang or vette you want, light to light and see who wins.

my buddies race their huge diesels against anyone who has more then 5k to run and win every time

strech117

ya i was looking at some thorley ones that will be ideal. i wouldnt have any idea how to stroke it out or change the cam, and anyone who would im thinking would charge an arm and a leg to do it right?

strech117

and agreed about the trucks.

superj

probably. have to make friends with some gearheads

strech117

ya. any idea on companys that make something i can replace the carpet in my jeep with?

fishtaconc

Carpet? thatll do nothjing for your HP LOL....a lot of people myself included replaced carpet with spray on bedliner you can put carpet. over it if you want

N20jeep

bedliner is the way to go

ergolarry

My apologies in advance for the wordiness of the following, but in my personal and professional experience of being an engineer for most of the big three in the past, in addition to building 70+ hand built cars in my own shop, the best place to start is to ensure that the your basic maintenance and repair is up to date in order to improve performance. Everyone seems to assume that the power that they have is the factory rated output when new, that exhaust and fuel delivery upgrades are required to get the output they desire now.

In reality, sadly, there isn't one of our used cherokee's out there with 177 or 190 hp after 20, 50, 100 or 200,000 miles. These things age. Actual dyno measured power of my 94' at the the wheels now, after 120,000 ish miles is in the 125hp range, and that isn't out of the ordinary or out of the range of expected performance considering parasitic losses due to u-joints, drive-shafts, normally worn rings, bearings, injectors, egr, o2 sensors, transmission etc.

Before I would consider upgrading to improve real world performance, I would address the losses due to wear and tear to get my vehicle closer to what it was when new. Factoring for normal parasitic losses and stock wheel/tire size and final drive gearing combinations, it isn't uncommon for a 4wd vehicle to lose 25-30% of the factory rated flywheel power ratings by the time the power gets to the wheels, and this is with new condition components!

Places I would first look to improve performance (not exclusively hp and torque but the actual the application of it) back to new like numbers would include the following, in no particular order:

1. O2 sensors
2. EGR valve
3. fuel pressure
4. compression, leak down for valve sealing, blow by
5. manifold leaks, catalytic converter related to age (If its original, it doesn't owe you anything) and back pressure leaks. Too little back pressure will potentially improve throttle response but ultimately hurt torque.
6. If its a 5 speed transmission, verify clutch engagement and disengagement. A worn or poorly functioning clutch will negate all power improvements that you make: power application at the wheels is what matters.
7. Worn u-joints
8. Brakes: crazy to think of brakes making your vehicle faster, but brake drag from poorly adjusted drum brakes will certainly slow you down.
9. Wheel bearings: excessive friction due to failed or failing bearings are an obvious source of parasitic drag losses.
10. Air pressure: how much additional rolling resistance is caused by rolling around on 12 psi 37's?
11. With your 70 lb beadlocked 37's, what is your final drive ratio? Do you need to re-gear to restore acceleration and mechanical advantage that the anemic oem 225/70/15's had?

I don't want to sound like I'm suggesting that after market power adders are a waste of money, I'm not. I'm just saying that maximizing the performance you have available to begin with by first doing the unglamorous maintenance will give more bang for the buck. Individually, addressing each of the items of suggested looking at first won't yield much, but by ensuring that your rig is in the best running condition with the overlooked (until they fail completely) items first, your performance will be much closer to when it was new and the additional gains from headers, injectors, intake etc will be much more dramatic. The good news is, by addressing the basics, your jeep will be more reliable, fuel efficient and perform better.

Remember: hp is only the rate of application of torque.

strech117

ya man, i can understand that fully. and i was actually going to be doing an engine rebuild and total driveline patch up before i started modifying anything.
ive just been looking for idea, so that once i have it running as close to off the line as possible ill have somewhere to go with it.

and carpet totaly boostes HP... ... ok well atleast it looks good. any specific brands of bed liner that are cheap and work fairly well? i think it would be lame to get the engine performing well without redoing the inside and outside.

ergolarry

The idea of carpet changing performance seems absurd, but there is some validity to the concept. When I was in engineering school I was a member of the Formula SAE race team at my university. The figure regarded as gospel for the race cars was removing 10 lbs= 1 hp, now the ratio may not be the same for cherokee's, but the concept is correct.

Removing mass that has to be accelerated means that the effective hp is greater. Now, unless you're a carpet installer and carry enough berber around in the back of your xj to wall to wall the astrodome, you're not going to make your jeep into any racer, but... every little bit of saved weight counts.

I often think of my poor (compared to stock) mileage and think of all the long dead dinosaurs I get to burn while smiling. Then I consider my fab'd bumpers, giant tires, full size spare, recovery gear et al and think that really, 15 mpg carrying all that, isn't too bad when you think of it.

strech117

hahaha sarcasm dude.