Drivetrain comparisons..need help

[Nightpath]

I'm finalizing my decisions on doing a drivetrain swap from an XJ to my Eagle. Looking at trying to save a few bucks where I can, get the most bang for the buck since the car will be my daily driver, possibly some long drives as well, so I have a few questions :

- Stock Eagle drivetrain is old and slow, is it heavier than an XJ drivetrain with AW4 and NP231 (or 242)? Wondering if the swap will save any weight overall. Someone told me that they thought it was 100 pounds or so lighter.
- Anyone that has done the drivetrain swap (stock Eagle to XJ drivetrain listed above) have any numbers MPG wise for the change from 4.2 carb'd to 4.0ho fuel injected? Listing any gearing changes would be a bonus.
- I have a buyer lined up for my old 258, but I have access to other 258's. Would I benefit from stroking my 4.0 HO engine? By benefit I mean will a stroked engine gobble the out of my gas tank? I know it provides more torque and horsies but I don't want to ruin economy.


I'll probably have more questions

[Jurjen]

I have not seen a succesful drivetrain swap on this forum yet. It is not a straight swap.
A lot of technical skills and knowlegde, both mechanical and electrical are required.

Just some things that come to mind:
1. The support for the front diff interferes with the exhaust pipe coming from the manifold.
2. AW4 controls need to integrated (and first separated) into the Eagle wiring.
3. How are you going to integrate the XJ control wiring into the Eagle dash?
4. Some engines the fan doesn't line up with the existing fan shroud (go for electric fans?)
5. Drive shafts need to be lenghtened/shortened.

Why are you looking for a better MPG, is the Eagle still your daily driver? I would keep the Eagle original and buy an additional XJ as a DD in that case.

[Nightpath]

I've gotten most of the swap figured out, that's not the point of my post. I'm cramming the whole 4.0, AW4 and 231 in with the wiring harness, I'll figure out what wires need to be mated to what under the dash, and the rest I won't bother with. It's OBD1 so it's fairly straightforward as oppsed to OBD2.

I'm just wondering people's experiences with this.

[eaglefreek]

Where is this 100 weight savings coming from? I would guess the XJ stuff to be heavier. The engine should be the same and  the transmission has extra gears for OD and the transfer case has low range gears added.

[Nightpath]

I have no idea, he never did tell me exactly what. Just said that some parts in the 258 drivetrain were heavier because the aw4 used lighter metals. All looks about the same size to me.

Wonder if I can get a industrial weight to measure it all on when I haul each out 


edit : found a site that says the block construction/material is the difference in weight.

4.0L I6 is 515 lbs.

[amchornet]

That sounds about right to me. I would think the aw trans and case would be heaver also. I have the 42re trans which I like more than the aw. The 42re is just a growen up 904.lol I am not installing it at this moment but it is on my list. I have the 2.73 gears inmy eagle if I rember right and I used a web gear calculator to figure my engine rpms. It said with the 42re I would be doing 72 mph at 2000 rpm in 3rd gear and overdrive would be 102 mph ar 2000 rpm. If my memory is correct.

[Nightpath]

Far as I'm concerned there's a good chance it is lighter due to the newer construction and materials.

Before the wife nagged me for supper and hte kids got on my PC I found a site that states that the block of the 258 is a heavier construction than the 242.

Eaglefreek posted a picture comparison of the AW4 and 998 here ( http://img.photobucket.com/albums/v637/svoman2300/AW4%20Swap/2013-08-05_14-36-23_830_zps016d6959.jpg )

Seems even though the 998 is shorter by a few inches it seems to have a cluster of extra components on it that looks like it'd cause it to weigh significantly more.

129t-case seems larger than the 231 (242 in this pic, which is about teh same size as the 231). ( http://img.photobucket.com/albums/v637/svoman2300/AW4%20Swap/2013-08-05_14-37-47_19_zpsfd0d906c.jpg )

In all honesty there's probably not a lot of significant difference, but from looking around at pictures and threads the consensus is that the XJ drivetrain is lighter. But what matters is the power, and the near double power from a low KM engine will more than make up any differences in weight.

Putting all this in words puts it in perspective. I kind of want to keep the stock Eagle t-case and fit it to the AW4 since that would make the swap that much simpler. Probably end up with a NP242 in it down the road though, it seems that it would fit perfect with the Eagle's persona.

[carnuck]

The viscous coupler isn't light either!

[Nightpath]

Lol... Older stuff tends to be built heavier.

[DaemonForce]

The viscous coupler isn't light either!

Hahahahahah! 10lbs of crammed into a 5lb case. (≧◡≦)

From what I've noticed, the AW4 is a little heavier than the A998 and the NP229 is MUCH heavier than the NP129.

The 4.0L is considerably lighter than a 258. Not sure where the 232 sits on this scale but when my final swap is an EFI 151, it's definitely going to be lighter than the entirety of the original drivetrain.

The most ideal 6 would be a rebuilt 4.0L bored out .03/.04" and using a remachined crank from a Hornet. The 4.0L behavior is like a new car with less torque than the 258, so it has a middle and some top end it's not hotrod territory. It's still not ideal where we tend to be when driving around in....Civilization. O_o

Some immediate responses to obsolete thoughts...
1. The exhaust will interfere- Don't worry about the exhaust. It shouldn't even be there during the planning stage. I would tear it out if I could. The manifold will interfere? I'm still on the fence about cutting into it, making a nice flat mating surface for it and making a turbo 6. The angle on some stock headers will either interfere with the diff(good sign) or with the block(bad sign). I'm a little more than marginally blessed here.

2. AW4 controls and integration...The computer and wiring modification for an AMC wiring block. Snore. This is why I'm doing a basic integration with the computer for a manual and keeping the torqueflite. This is one area where I simply do NOT have the patience.

3. Controls in the dash? I wouldn't bother modifying the dash. Maybe the clusterpod and radio but the rest should be left alone.

4. Ford Contour?

5. Time to go picking.

Most of the owners looking for better mileage are usually stuck bumper to bumper so no amount of help will work. Some of us are stuck in an insanity circus with too much on our plate. When I bought my Eagle the 258 engine was in okay shape but constant interference by incompetent mechanics quickly destroyed it. The transmission became a revolving door issue for the same reason and after 3 months of an idiot playing keepaway with it, the bill was NOT worth what I got back but I had to have it. My Eagle was a daily driver for going up to the capitol for work and taking off for Portland on my time off. Time behind the wheel of the Eagle is extremely effective therapy.

[carnuck]

If someone was going EFI and needed to rebuild their 998 anyways, the 999 case I'm selling for $50 will work with a 999 torque converter (I recall reading the 42RE converter in Grand Cherokees  being the same and the flexplate certainly works with HO EFI)