LQ4 6.0L/NV4500/NP241c in an XJ - Q's before I waste a bunch of money :)

Been holding off on pulling the trigger on an SBC swap for a while, hoping something in my drivetrain would finally snap, to justify the upgrade.
4.0L is very tired. Still makes okay compression, but has a cracked #6 cylinder (has run like this since I got it 6 or so years ago), and just doesn't make a tonne of power. The AX15 is sloppy and syncros are pretty rough. NP231 has a bunch of play, though I've never figured out what's normal.

The good:
* Frame stiffeners (almost tied in bumper to bumper).
* Bumpers (to help add torsional rigidity and protect me from Samurai).
* Rear shocks relocated behind rear seat.
* 2x6 sliders
* 6.5" of "up". Front long arm.
* D30, 4.56, WJ knuckles, 1t x-over, akebono brakes, chromoly, lunchbox, sleeves waiting to be installed.
* D44, 4.56, KJ discs, chromoly, lunchbox, otherwise stockish.

Long short, the long term plan has changed. I'm pretty happy with the axles behind the 4.0L, but it sure would be nice to have some unsprung weight. Thinking about throwing a 14bolt/D60 combo in anyway, and 4-linking the rear. I've been thinking about the 4-link for a while, but as long as my leafs keep doing their job, I just can't be motivated. A 6.0L would be more than sufficient motivation (though I'd probably just run the leafs for the first bit, and build an ugly ladder bar for the short term).


All that said, back to the drivetrain. I'm not entirely incompetent, but I've never done a swap of this magnitude and I'm trying to line up as many ducks here as possible before pulling the trigger. The plan is to buy another XJ as a daily driver, or for the swap, and keep one running so I don't foolishly rush the swap to hit the mud.

One thing that's always bothered me about this swap is that there are really only 2 or 3 companies who make driveline adapters, and they're crazy expensive. Spending $600 on a trans-tcase adapter wouldn't worry me too much if I thought my NP231 would hold up to V8 power, but I've seen too many grenade. Same goes with the SBC > AX15 adapter. I already sorta need a new AX15, and I know it's a respectable trans, but between 350hp and 35-37" shoes, I really just don't want to spend an extra grand to retain a weak link.

So, I want to try to build everything with very easily accessible parts. The current prospective donor is a 2000 Silverado 3/4 Tonne, with an LQ4 6.0L, NV4500 and NP241c. I know most guys would prefer to go with the 4L60-E, and I may end up that route. My concern with the auto is that I tend to blow up my brakes at the least opportune moment and find engine braking has saved my life at least once. That and auto is for girls. I just prefer driving stick. I'm not married to manual at this point, but I figure if I'm going SBC and I've got an NP241c, I can mate up any chebby trans between them without having to spend another grand on an adapter.

So. Of course no one seems to have done this entire driveline and I'm wondering if anyone knows why? SBC > XJ is common. NV4500 > XJ is uncommon but no unheard of. NP241c > XJ is very uncommon, but the only reason I can figure is that it's only helpful when you've got an SBC already. Does anyone have any idea why the NV4500/NP241c aren't commonly found behind SBC powered XJ's?
I know the NV4500 will require some smooth talking to fit in the tunnel, and the tunnel will have to be reinforced after being ripped open, but that's not that big a deal. The NP241c clocking seems to be pretty close to the NP231j, and JB conversions makes a 1" SYE to replace that aweful tail cone. I figure $400 for the SYE (that I'm going to spend on an SYE for any t-case unless I retain the NP231) is a better plan than a grand for any other adapter.

So in summary, I"ve got a 6.0L, NV4500, and NP241c donor complete, for around $2300 that I can probably pick up in the next few days. Worst case, I decide against the NV4500, and I've got a buddy who's been looking for one for years. The 4L60E can be bolted to the NP241c (i believe).

The plan would be as follows (I'm hoping someone can point out wherever I'm missing something obvious or making bad choices):
* LQ4 goes into Jeep.
* Big silly radiator goes in front of LQ4.
* NV4500 goes in Jeep. Requires tunnel modification to fit flat.
* NP241c gets a stubby SYE.
* This length shouldn't be more than an inch or so longer or shorter than my current driveline. I may be able to retain my driveshafts.
* No idea what I'm doing about gauge cluster. Probably try to work a Chebby or aftermarket cluster in.
* Stock fuel pump gets it's regulator removed. External 50-60 psi regulator and filter go inline.
* Drive by wire throttle will be taken from the donor.
* Tcase linkage will probably just fit. May require minor modification from stock.
* My axles probably won't survive the 6.0L, especially with the 6.5:1 first gear in the NV4500. I'm not super worried about this right now as I can always throw in the 14 bolt that came with the donor, and pick up a D60 for the front. If I blow up an axle, it's not the end of my day.
* I figure I can probably get this all done in an afternoon right?

Oh yea, that NV4500's first gear is ridiculous. With my 35's and 4.56, with the almost 3:1 low and 5.6:1 first gear, that's an EEVIL crawl ratio. I'm guessing first would be entirely useless on the street (though maybe I'll be surprised when I can rev past 4500?).

I don't have my heart set on anything yet. I just get sad every time I get out of my roomies 5.0L foxbody and into my XJ, and I don't trust my XJ to get me home. Lack of power and reliablity = not a good feeling.
I may end up holding off for a good LM7 and 4L60e, but either way I'm still hoping to understand why no one else has done the 4500/241 combo.

Thoughts? (Other than "gtfo and post in n00bs board".... ).

DO it!,
Also, consider reading Frank Z, John D, xj+rcks, etc LSx swaps. I believe xj+rcks is running a 4500 with his motor.

Johnnie Walker said:

DO it!,

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Heh. It's getting difficult to convince myself to hold off at this point. I can't see anything wrong with the plan, other than the fact that I'm usually too impatient to do things well, but that's what the second Jeep will be for.

I really wanna hear other guys experience with any of the components I'm thinking of. I strongly suspect there's a damn good reason that the 4500 and/or the 241c aren't more popular for this swap, but I just can't find anything.
The only things I can come up with are :
NV4500:
* Most guys want auto.
* 4500 is overkill (but I really don't want to deal with a 3500 as they seem to shit the bed every time they touch water).
* Requires tunnel modification.

NP241c:
* Has a long-ass tail cone (but the tail cone is going to be removed from any case, so ...?)
* Maybe most guys doing the SBC swap are just more hardcore, and dropping in Atlas's? THis would make sense except that there are so many adapters available for the NP231/D300/whatever. I just don't see anything wrong with the 241.

Nv4500's are the only way to go. FYI, yours isn't the early 6.32:1 version, you have the 5.8:1 version. Ideally I'd love to do the LQ4/nv4500 setup in my jeep one day, use all the factory clutch stuff and keep it with easy to get parts. I'd be swapping my StaK 3spd on the back though.

Oh, another question I haven't really found an answer for.
What sort of mileage should I expect from an LM7 vs LQ4 in a sub 4000lbs XJ?
I hear heaps of guys (as well as Novak and others) saying 20mpg from an LM7 is an easy mark. I've also heard that the LQ4, assuming you're not driving like an asshole, should get about the same. I think they were rated to around 18mpg highway in a Silverado 2500HD which has a curb weight of around 6300lbs. Am I crazy to hope for at least 18-20mpg with either the LM7 or LQ4 ?

I would go with the bigger motor to start. Mileage should be about the same. But you will have more power. In theory you should see high teens at the very least.
I think people more want the convenience of the Auto vs manual. And it may also be in part to what they find as well.

So, I took the potential donor for a quick test drive. I can't say I was blown away. It was slow, but felt like it had heaps of power to spare but just didn't wind up fast enough to use it. Who's driven a 6.0L with an NV4500? How's it supposed to feel (stock)?

Connected my OBD, didn't throw any codes, all the numbers looked about right. I'm not sure if it blew a bit of smoke when we first started it up, but it looks like it hasn't been run in months.
What should I be looking for in the 6.0?

blistovmhz said:

Oh, another question I haven't really found an answer for.
What sort of mileage should I expect from an LM7 vs LQ4 in a sub 4000lbs XJ?
I hear heaps of guys (as well as Novak and others) saying 20mpg from an LM7 is an easy mark. I've also heard that the LQ4, assuming you're not driving like an asshole, should get about the same. I think they were rated to around 18mpg highway in a Silverado 2500HD which has a curb weight of around 6300lbs. Am I crazy to hope for at least 18-20mpg with either the LM7 or LQ4 ?

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Don't count on the mileage, you will always drive it like an asshole. Although it's been awhile since I researched these things, I would look at the 241 before I used a $600 adapter again.

I ended up with an 05 5.3 and 4l60e.
I've got an NP231j with an SYE, so I picked up an NP231c (27 spline 5 bolt). Will throw the guts of the C into the J, retain the J SYE and output shaft, and stick it all to the trans with the AA kit (minus their input shaft). Gives me trans mounted VSS and retains Chrysler Speedo for the time being.
Just thinking about trans/case linkages now, and trying to track down an appropriate rad (hopefully with a built in trans cooler). Any suggestions on the rad/cooler (assume I've already torn apart my rad support, so anything that really fits in the general area will do just fine).

blistovmhz said:

Heh. It's getting difficult to convince myself to hold off at this point. I can't see anything wrong with the plan, other than the fact that I'm usually too impatient to do things well, but that's what the second Jeep will be for.

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Three options for the impatient (from experience)
1.) Open your wallet, buy off-the-shelf components that make life easier
2.) Wind up doing it three times and wasting hours and hours of your life half-assing things "for now"
3.) Learn to be patient, buy the top-shelf supplies, get your soldering / whatever skills right & master your impulsive behavior: it will be "down" a while

Hey, Eyup.
Option 1 seems somehow morally wrong..
Option 2 ... I tend to do often.
Option 3, we'll see.

Thus far I've been able to maintain pretty good restraint. I haven't pulled my 4.0L yet (a feat). Waiting till I've done everything that can be done out of the vehicle. I'll have the drive train complete and possibly tested before I start tearing into the Jeep. The swap is really not looking all that difficult now that I've got most of the hardware in front of me. If most guys think wiring is one of the bigger parts of the job, this'll be cake (for the most part). I suspect the hardest part for me will be bending lines for fuel/trans, and possibly figuring out the shift linkages.

For lines, I'd use Dorman's nylon or Summit Racing's house brand push-lock AN hose. I wouldn't bother bending up hard line into complex shapes... push-lock hose is cheap enough and nylon lines are dead simple to run the whole car with.

Wiring has been the most time consuming part of my LS project but that's because I went with option #2. Now that I'm applying option #3, it's really improved things.

yossarian19 said:

For lines, I'd use Dorman's nylon or Summit Racing's house brand push-lock AN hose. I wouldn't bother bending up hard line into complex shapes... push-lock hose is cheap enough and nylon lines are dead simple to run the whole car with.

Wiring has been the most time consuming part of my LS project but that's because I went with option #2. Now that I'm applying option #3, it's really improved things.

Click to expand...

Dag, that fuel line will save some time.
What about trans cooler lines? Are there any reasonably priced options that don't include bending steel lines? I really hate bending lines. Like, I'd rather be attacked by a pack of rabid raccoons than bend hard lines.

What's the hold up with your wiring? Engine harness seems ... almost suspiciously simple. We're just planning on using a stock harness for now until the Jeep is running and then make a new, much lighter harness after. My roomie (the wiring guy) and I looked at it and figure half a day to build a new harness from scratch.

I feel like the Jeep side of the wiring will be substantially more work, but that most of it doesn't need to be done to get the engine in and running. No?

With my wiring the hold up is that Round 1 was I had an incomplete pile of parts and a month left before I had to move the whole project to a new living space. Self-imposed deadline of driving truck on to the trailer, so I hacked stuff together. Next time I touched it, it was outside the garage and I didn't really have a plan, so I made a few fitment improvements but it still didn't lay right. This time I figured it out, it fits nice, etc. Getting it running has never been the hard part: it's just making it look right & route safely.

Trans cooler line, I'd save the stock lines and see if they can be partially reused. You can buy tube-to-AN adapters that will slip over an existing hard line and allow you to plumb anything you can imagine off of that line. A small tube cutter & the Summit Racing web site will be your friends here.

Also - I don't know if nickel-copper line is available in 3/8" but it is much easier to work with than steel. It's worth every penny for the time & frustration savings. Aluminum tubing is another option too but it needs to be well supported with clips to the body to avoid metal fatigue. Both are easier to work with than steel line.

That Dorman fuel line? It's made of Nylon #12. Look up the hydraulic fluid resistance of Nylon #12, and see if any of the available fittings for that stuff will connect your transmission cooler lines. Note that barbs made for rubber hose won't work with the nylon, though.

Hey, so I picked up an NP231c and NP241c 6pinion planetary from the wrecker last night. I've got a 98 NP231j in my Jeep, and another 231j on the floor from my buddies wrecked 93. Does anyone know if the cases are identical?
I'm planning on putting the 231c guts (and 241 planetary) into the 231j, retaining the j output and SYE housing, but as the bastard 231 will be bolting up to AA's 4l60>np231j adapter, I wanna make sure the cases are pretty much identical before I tear my spare 93 case open and start the swap.
The only difference I can think of is the input/output spline counts, but afaik, the actual shaft OD's are the same. Anyone know if this is accurate?

Actually, my NP231c I picked up from the wrecker has the correct 6bolt pattern to mate up to my existing trans>case adapter. The only reason I was looking at AA's adapter was for the VSS, but after doing some more messing around with my cases, I figured out some more stuff.

AA's np231j, 27 spline input shaft is actually an np241c 27spline long input (narrow bearing).
The NP231c bolts right up to the 4l60e with the factory 6>6 bolt adapter. The only reason I wouldn't run this setup are:
1. The np231c input shaft is too short for the adapter and I wouldn't get much spline engagement.
2. I still need the GM VSS.

I'm wondering if anyone can help me out here. The AA kit comes with a 40t reluctor that clamps on to the 4l60e output shaft, just past the splines. As far as I know, the NP231c/j cases are pretty near identical except the front bolt pattern.
Could I just buy the 40t reluctor, bolt it onto the trans output shaft, drill a hole in the factory adapter and mount the VSS there, then bolt the NP231c case with the NP241c 27spline long input, and my NP231j SYE and output shaft?

THis would give me the stronger internals of the 231c (wider chain mostly), the stronger and longer 241c 27spline input, and it'd bolt right up to the factory adapter. This'd save me another $200 and I could get started on it tonight. All I'd need from AA is the 40t clamp on reluctor.
Anyone KNOW FOR SURE if this would work?

EDIT: NVM. This of course won't work as the Jeep NP231j bolt pattern doesn't match the factory 6 bolt GM adapter. Derp.
Going to just order the kit from AA, minus the input shaft, and hope to hell that the 241c input I have will work.

any vss will work if you use software like hptuners to change the expected pulse/mile count. So if you had a case with a vss that did 8 pulses per rev you could just use that one and change the tune to use that.

Right, but either way the Jeep speedo gear, from everything I've heard on the Internets, won't work with the GM ECU. Do you know of a way to make the Jeep VSS/Speedo gear send useful data to the GM ECU ? My understanding was that (aside from the Jeep VSS signal being of the wrong waveform), the Jeep VSS simply couldn't produce high enough resolution for the GM ECU, and that everyone who's tried it has said it results in a real flaky shift pattern, and ridiculously poor fuel economy.

Dakota digital speedometer might work..

It's Dakota Digital, who might have a black box you can plug in to your 231 that will produce an acceptable waveform for the GM computer, OR see if you can duplicate this right here