Reliably increasing power for tow capacity

[SolarBell]

This might be in the wrong section. Mods, feel free to move.

I recently bought a good sized pop-up camper. It makes my wife happy to get out and camp so it's worth it. I even lifted it so I can take it down mild trails and get into the backcountry. But it's pretty heavy - almost 2900 pounds dry and a GVWR of 3500 pounds. I can pull it ok on the flats, I can do 0-60 in about half a mile. Problem is as soon as I get into the mountains it just struggles, barely maintaining 40 on some of the bigger hills.

I'm looking at various options of what to do, including the possibility of getting rid of my trusty XJ for something a little bigger. But the price difference is sizable to go up to what I'm looking at, so I wanted to gather opinions on options for increasing power in my XJ while still keeping really good reliability. I drive this thing every day in the winter and can't afford to have it fail or have to futz with it every other week to keep it running right.

I see 3 options for increasing power:
- Forced induction (turbo, super)
- Stroker
- Motor swap

I figure something around 250-300 horsepower would do the trick without being terribly overkill for the drivetrain. Current setup is: 2000 Sport, 4.0, AW4, 242, D30 and C8.25 w/ 4.56 gears and 33's. Receiver is built into a custom rear bumper with 2x4 box inserts into the frame, so I'm pretty sure that part is strong enough. I expect to fully plate the uni-frame if I go this route.

What say you ? I'm still in thinking mode, but I would need to stay under $3k to make this feasible. If I'm looking at $5k then I might as well sell the XJ and be most of the way toward something else. Oh, and if it takes 3 months of weekend fab I'm probably not interested, I do have to get to work most days. Did I mention it has to be reliable?

Thanks in advance.

 

[freerider15]

Did I mention it has to be reliable?

Thanks in advance.

This is THE biggest issue you're going to run into with stroking, supercharging, or adding a turbo to an XJ. Some have had those various mod's done and had no issues (but many of those are proper $$$ swaps). However...most people I see that do one of the above have issues in some form or another.

In all honesty...for what it cost to do those, it would be better to step into something else than an XJ.

If it we're me I would look at selling the XJ, and picking up a V8 WJ. They're not that expensive, roomier and more luxurious, and should have the relative power you're looking for.

As much as I love XJ's, there are some thing's I prefer another vehicle for (i.e. remotely heavy towing).

 

[yossarian19]

I'd get geared to 4.88 or get a wj. For 3k I don't think you can make an xj a tow rig. Only way I see it is maybe super charge plus wj brakes but that's tough to do right for 3k

 

[043500]

I'd get geared to 4.88 or get a wj. For 3k I don't think you can make an xj a tow rig. Only way I see it is maybe super charge plus wj brakes but that's tough to do right for 3k

I 2nd the 4.88's. I ran this combo in an XJ for 2 years pulling a pop up nearly the same as yours and it was fine.

Cheapest and easiest solution...plus the most reliable.

 

[sidriptide]

deeper 4.88 gears would help the most, but you are really just pulling too much weight, and the higher altitudes just kill your power regardless of how much power you are making. a V8 WJ will have less torque for towing than your XJ does, the 4.8L isnt the most reliable when it gets higher mileage, and the WJ has the same weak transmission as the ZJs. a WJ might be more comfy, but it wouldnt be the ypgrade you are looking for.
pack a little lighter and enjoy the slow lane...

 

[djlarroc]

what about a 5.9 zj?

i dont know if 4:88s with help that much. there's no replacement for displacement.

 

[sidriptide]

it really depends on how often you are making these trips. a few times a year i'd stick with the XJ and just spend a few bux on deeper gears. next step is a smaller trailer or larger tow rig.

 

[yossarian19]

what about a 5.9 zj?

i dont know if 4:88s with help that much. there's no replacement for displacement.

IIRC, the factory gears were 3.55s for automatics, 3.08 for stick shift. Tow package with the automatic, they added hitch (duh) + trailer wiring, auxillary trans cooler in front of the radiator, and - wait for it - 3.73 gears. 456 w/ 33s is about comparable to 3.55s & factory 28.5" tires.

I think 4.88s will help. More torque at the wheels + rpms will consistently be closer to peak torque range of the 4.0.

5.9 ZJ will out-tow an XJ. So will a 5.2 ZJ, a 5.7 XK / WK, a 5.2 Durango, a Tahoe, etc. I'll bet, though, you can get "good enough" results for $800 in gears and save yourself the extra gas / purchase cost of going up-sized.

 

[SolarBell]

We're planning on getting out at least once a month during the summer - so often enough. I don't have the money for two rigs so if I get a replacement vehicle I want to be able to wheel it a decent amount. Can't get a smaller camper, only just got the one I have.

A V8 Grand is on the list of potential replacements, including (gasp) a Tacoma.

I'm honestly not convinced one step up in gears will solve my issues. Trying to climb 6% grades at 9,000 ft is tough on any vehicle. Plus the 4.56's are less then 6 months old so the wife would kill me.

 

[cheapcherokee93]

a V8 WJ will have less torque for towing than your XJ does, the 4.8L isnt the most reliable when it gets higher mileage, and the WJ has the same weak transmission as the ZJs.

:bs:


hmmm lets see

first off its a 4.7
second, a regular non HO 4.7 makes 295 lb/ft vs 2000 XJ 4.0 makes 231 lb/ft
a HO 4.7 making 330 lb/ft

so how do you figure it makes less torque? i've also driven both XJs and WJs and can attest to the extra torque you can feel in the WJ.

i can probably agree with you on the reliability somewhat, i worked at a chrysler dealer for a while and saw lots of those engines start to fall apart after 150k, but that was usually due to lack of maintenance.

and lastly, you are also wrong about the transmissions.

ZJs use 42re, 44re, and 46re while the V8 WJs use a 45RFE, which is completely different. :nono:


i would recommend the OP consider a V8 ZJ (preferably a 5.9 ZJ because its got gobbs of torque compared to a 4.0) or a 4.7 WJ. they would tow much better than the XJ

 

[yossarian19]

Well, it might be time to cash in the XJ & get a 4.7 WJ with factory tow package. You'll like driving it better - I know I like the WJs better - more comfort, more power, more brakes. Plus it has the more manly 5x5 bolt pattern. Hell, I've about convinced myself that's what *I* should do.

 

[blondejoncherokee]

why not put some 29" a/t tires on for the drive up and keep the 33s in the trailer? then swap tires when you get there. I bet that would help a ton.

Make sure your jeep is in top running order. PLugs, o2 sensor, plug wires, TPS, exhuast leaks, and all of that good stuff.

Or you could sell the 4.56 geared axles buy some 4.88 axles off of CL and run 31s . Either way, do the tune up.

 

[bwinter1946]

Or split the difference and change out to 31s. That would help with gears and the brakes. Then you are not towing the trailer put the 33s back on. I would try to borrow some tires first and see if I liked before I bought.

I tow a 3,000 lb boat with my XJ. It does it but it is working to do it and I only have to go 20 miles to get to the lake. If I did it a lot, I would want 4.56 gears. In addition I did upgrade the brakes front and rear.

 

[Lowrange2]

Why don't you just buy a smaller pop-up camper? They make 8ft PuPs that your Jeep wouldn't notice that it's towing.

 

[Warlock1]

Golen stroker. 270 hp 320foot lbs torque with stock intake and exhaust.
305 hp and 370/380 foot lbs torque with 99+ intake, good header and exhaust, cold air intake, big throttle body, and other odds and ends. (it's been a while since I talked to them so I forget some of the specifics)

That'll do it.

 

[cal]

I'm with the others, stroker does sound like the answer here.

Try Russ Pottenger at Bishop Buehl racing engines, he's done a lot of strokers for Naxja guys and everyone has been happy.

Also, you need a GIANT trans cooler.

 

[SolarBell]

Ok, I'll bite. But for a Golen and everything required I'm looking at easily $5k - $6k. That's a whole lotta money for 100 horsepower when I can sell the XJ, put in that much cash, and get a nice V8 WJ or WK.

 

[cal]

If you're not building a race level motor, I'd expect to spend closer to $3500 not counting freight.

Talk to Russ and see if he can work something out with you.

Russ Pottenger
Bishop-Buehl Racing Engines
531 N. Lyall Avenue
West Covina, California 91790
Work (626) 967-1000
Fax (626) 967-7836
Cell (626) 673-2203
Email [email protected]
__________________

 

[cal]

That's a whole lotta money for 100 horsepower when I can sell the XJ, put in that much cash, and get a nice V8 WJ or WK.

And you're right, I think a 4.7L WJ would be a great option for you as well.

 

[David_Bricker]

Second a discussion with Russ. He built me a 4.6L stroker. Gobs of torque, though I'm not pulling anything.

Russ can build it to your exact needs. In my case, the torque comes on at 700RPM, and stays level until 4000. You may want something similar.

You may be on the edge of your $3K, but I don't think you will have reliability issues.

You probably want to do something about improving brakes, at least the fronts. WJ, Vanco, something.

David Bricker / SYR