5.2L Magnum XJ engine swap

[Gaius]

Really? Not that I've driven / seen a Magnum engine in a Jeep but the power figures don't look like anything special. More than that, the light research I've done doesn't show squat for power adders without camming it or going back to a stone-age carbeurator.

The power output isn't fantastic, especially when you look into the GM LS motors, but the 5.2 has a great powerband for the Jeeps, IMO. My 5.9 is all grunt, and feels like it has not great HP. The 5.2, however, is a revvy bastard that really pulls, and is a blast to drive.

You don't install a 5.2 or 5.9 for the most power to weight. You do it for ease of install and availability. Plus, I'm a Mopar guy.

 

[Bloose]

230 hp and 300 ft lbs torque. For a V8 its a dog in any vehicle.

But... 190HP and 235 lb ft of torque is even more doggy!

I know everyone thinks a header, free flowing exhaust, and a cold air intake are worth 40hp but their not! Getting 40 more HP from a 4.0L is not an easy task and even then there is no guaranty you'll be making 300 lb ft of torque. A stroker will do it but when your done you still have a rough running POS that needs premium fuel, and weighs more than the V8.

250HP + on a V8 is a simple cam swap away.

B

 

[Bloose]

You don't install a 5.2 or 5.9 for the most power to weight. You do it for ease of install and availability. Plus, I'm a Mopar guy.

Exactly!

 

[Bloose]

if your going to go 5.2, why not go 5.9?

HP isn't THE most important factor here. It is important but I'm looking for a balance of HP, fuel economy, and cost to do the swap. 5.2's are more plentiful than the 5.9's and for my needs a 5.9 isn't really required.

I guess it's the same reason people do 5.3L or even 5.7L swaps over 6.0L swaps. What's available for a good price is usually the motivator.

B

 

[Talyn]

But... 190HP and 235 lb ft of torque is even more doggy!

Nice flat torque curve, easy to work on and reliability is what makes the 4.0L desirable.

I know everyone thinks a header, free flowing exhaust, and a cold air intake are worth 40hp but their not!

Might get 10 hp to the wheels at most

A stroker will do it but when your done you still have a rough running POS that needs premium fuel, and weighs more than the V8.

And a V8 has great balancing characteristics, right? A stroker will only run rough if you make it that way. And they can be made to run on regular. Besides I haven't seen anyone recommend a stroker in this thread.

 

[Bloose]

I didn't say anyone recommended a stroker, I said to get 40 more HP from a 4.0L you would need to do something pretty major like a stroker.

As far as reliability the 4.0L's haven't been good to me. The oil pump on mine just failed at 135K miles. My wife's 2001 was dumping coolants into the oil at 75K and needed to be replaced. Her replacement lasted about 4K miles and busted the distributor drive (actually just a cam position shaft) which took out the cam. That too may have been oil pump related.

Plus their expensive to rebuild. As far as rough running, a good balance job may help but the 4.0L's, at least all 5 of them I've owned, have been anything but smooth.

The fact is, I personally am not a fan of the 4.0L. This is 100% based on my own personal experience and if you like them or even love them, great. I know most people run them for 200K + miles without incident. Doggy, expensive to rebuild, expensive to get good power gains, heavy, and for me, not the most reliable, are the reasons I'm not a fan. Again though, that's just me, if you love them then so be it. This thread isn't about what a POS the 4.0L is, it's about if there is a good reason that the Magnum V8's don't make a good donor motor for the XJ.

B

 

[kastein]

The 00-01 is known for the coolant/oil issue due to the 0331 head. I've also heard about cam / DIS sensor / oil pump drive issues and saw them first hand on an 05 (?) LJ wheeling last fall. Apparently it's known but they haven't found a fix for it yet.

My 91 has 230k hard miles on it, including running out of oil multiple times. Still gets up and goes great, had it bouncing off the rev limiter for a minute or two solid last winter going up a hill in the snow with an open rear diff, no 4wd, and street tires.

96 also still going great, I've been beating the hell out of it and it just won't give up.

98 might need a new motor but I'm not sure. Need to check compression and some other stuff before I condemn it, it's not firing right on cylinders 3 and 4.

Regardless I want to do the same thing you're planning. I started out looking for a 5.2 and then said to myself "if I'm gonna do a motor swap I might as well see what's available for 5.9s in 1 ton trucks with better transmissions before I settle for a 5.2", and that's where I am now. If all I can find is a 5.2 when I decide to buy the donor so be it, I'll plan on getting an ECU and 5.9 to drop in it later. It will be replacing the motor in the 91, which will probably go on to live in the 98 or sit in my shed as a spare in case anyone I know hydrolocks theirs wheeling.

 

[Talyn]

This thread isn't about what a POS the 4.0L is

Then why did you bring it up?

The 00-01 is known for the coolant/oil issue due to the 0331 head. I've also heard about cam / DIS sensor / oil pump drive issues and saw them first hand on an 05 (?) LJ wheeling last fall. Apparently it's known but they haven't found a fix for it yet.

The cam sensor/oil pump drive is known for freezing up. Happened to me once. Cam was fine luckily. I haven't heard that many incidents on the XJ, probably because it only had it for 00-01. I have noticed that it is a common problem on TJs and their variants.

 

[srimes]

HP isn't THE most important factor here. It is important but I'm looking for a balance of HP, fuel economy, and cost to do the swap.
B

Those motors aren't know for good fuel economy, but maybe they'd be alright in a jeep. I do like the idea of a cheep and easy v8 swap.

 

[Bloose]

Those motors aren't know for good fuel economy, but maybe they'd be alright in a jeep. I do like the idea of a cheep and easy v8 swap.

No Jeeps are known for good fuel mileage. I just figure a 5.2 would get better fuel mileage than a 5.9L yet meet my needs.

B

 

[Bloose]

Then why did you bring it up?

The cam sensor/oil pump drive is known for freezing up. Happened to me once. Cam was fine luckily. I haven't heard that many incidents on the XJ, probably because it only had it for 00-01. I have noticed that it is a common problem on TJs and their variants.

This wasn't a thread about whether or not the 4.0L is a POS.

Is that better? The fact is, when you look at all of the trouble I've had with all of the 4.0L's I've owned I'd just rather have anything other than the 4.0L. Both my '98 and my wife's '01 also have huge problems with cylinder misfires. Mine since new, hers for a long time now but not since new. Add in the head problem on hers, the Distributor/cam sensor shaft on both hers and mine, and 2 bad fan drives on mine (one of which sent the fan through the radiator) and if I can help it I'd like to be done with the 4.0L.

As stated I know lots of people put tons of miles on them without issue but that just hasn't been the case for me.

B-I have a real nice 4.0L I'll sell you-Loose

 

[yossarian19]

Hey man, I support you wholeheartedly. I've thought about it myself, the 5.2 in an xj, but had to get realistic about my cash & available time. Not to mention space for a dead XJ.
Go Mopar, get it done, take pics.
There was a guy, haven't seen him active lately, went by 5.2literxj or something similar. Anyway, yuo can guess by the name that he's already done the swap and IIRC he loved the results.

EDIT: Found him : http://www.naxja.org/forum/showthread.php?t=930858

 

[DieselSJ]

Stroker >>> stock 5.2

Stroker will make equivalent, if not better, power than the 5.2. Plus it is 100% bolt in - no screwing with mounts, radiator, exhaust, and the 1000 other things that go with an engine swap.

 

[Gaius]

Stroker >>> stock 5.2

No.

 

[FlexdXJ]

Stroker >>> stock 5.2

Stroker will make equivalent, if not better, power than the 5.2. Plus it is 100% bolt in - no screwing with mounts, radiator, exhaust, and the 1000 other things that go with an engine swap.

But he wants to get away from a 4.0. So go for the 5.2 Bob. Better hurry WF is 11 months away!

 

[anthrax323]

It looks like there are a few people interested in this swap now (and the more I think and read about it, the more I'm on board with it).

Anyone have a rough idea of what model year donors would be the most direct swap into each generation of XJ? I, too, have a 2001, which would be the focus of most of my interest.

I really might need to wait until after I move back to TX to seriously consider this, but it'll be even more important then as the business I'm taking partial ownership in will quickly require a trailer... And God help me, I never want to tow a trailer with the 4.0 again (on 31's... on 3.55's... ).

 

[kastein]

I've been looking at it because I'm gonna have the whole drivetrain out already, and I have 4 vehicles so I don't really have worries when it comes to having to DD something else for a while.

It's been on my mind for probably around a month or two at this point. I did a brake job for a friend of a friend on a 5.2 ZJ and took it out on the highway for a test, floored it expecting it to be a pig since I'm used to 4.0 ZJs... and was quite pleased with what the butt dyno said. Been thinking about swapping the MJ over to a V8 ever since.

I'm not sure how much the donor matters to most people. I am aiming for the Rams, preferably as early in the model series as possible (94 to 02 is the range I've been looking at) because the electronics will be more accomodating to modification the older it is. I need to do a bit more research but I'm hoping the early end of that range uses the CCD bus just like all the XJs do because I'm somewhat familiar with it, and have a chance of making a 97-up instrument panel work with the Ram ECU (need to verify if this is possible or not, most Chrysler brands used CCD for quite a while.)

A 2001, you are going to have an interesting time. Talk to Frank Z and John D, read their build threads. Both of them did non-Chrysler V8 swaps into late models iirc and took different approaches to getting the gauges working.

Also remember that depending on smog checking and your state inspection station's inspection rigor, you may need to get a donor vehicle that is newer than your XJ, and preserve *all* emissions equipment from the donor or recipient, not sure which. This would all be going in my 91, so I was all set there, but if it is a worry for you it will narrow your donor range down a lot.

 

[XJEEPER]

Stroker >>> stock 5.2

Stroker will make equivalent, if not better, power than the 5.2. Plus it is 100% bolt in - no screwing with mounts, radiator, exhaust, and the 1000 other things that go with an engine swap.

I beg to differ. 100% bolt in would imply that there are no additional modifications required, simply bolt in the new stroker motor and drive it. Seems to me from all the documentation I've read, you need to add wideband 02 sensor/gauge, larger injectors, larger TB, adjustable MAP, aftermarket tuning module to get the stroker to run properly.

The outcome that Bob is looking for is what I got with the salvaged 4.3L Chevy/TH350 swap that I did in a truck back in the 90's.
Looked stock under the hood, used all stock sensors and ECM, had triple the HP over the stock powerplant and ran like a top for the 5 years I owned it and passed IM with flying colors.

 

[Darky]

Shelbyluvv is swapping a 5.2 into an MJ. I think he's just about done, or close to it. Unfortunately he had a falling out with some of the people here and doesn't log in any more. He used a ZJ as the donor. IIRC he had to lower the motor mounts to fit it under the hood without getting a cowl hood. I think he used the harness from an XJ to tie it into the guages since the MJ harness was shot.

 

[yossarian19]

Cowl hood, lower the motor mounts or delete the AC. Thats the way I understand it, anyway.
Stroker may make more torque / HP than a bone stock 5.2, but from there you are looking at forced induction to increase power. You can get a lot more from even a 5.2 than you can from a stroker once you start trying.