LX Forums Forum banner
31K views 31 replies 12 participants last post by  Chizach124 
#1 ·
Yes, I believe I'll take one!

It ought to go well with the 6-speed stick shift transmission I already have installed.

Haven't decided yet to spring for a separate donor 3.5L V6 engine, or just yank the engine out of my Magnum.
 
#3 ·
Nope, no interest in losing my 6-speed transmission, having to heavily modify my floorpan to accept a Challenger 6-speed, trying to figure out how to get a V8 setup to accept a manual transmission, installing beefier front springs, adding 250 or so more pounds, knocking my gas mileage down significantly, or doing something that's frankly already a pretty common mod.

Besides, I'm swapping in a really cheap Pacifica V6, not having anything bored out. No custom engine work required. I estimate that it will take much less customization than putting in my 6-speed.
 
#8 ·
First pics of the replacement engine.











Debating whether to keep the timing belt covers. There might not be enough hood clearance for the alternator, where it would sit on top of the left side.

Not sure if I can keep the intake manifold. That depends largely whether I can get the lower intake manifold to play nicely with the radiator.
 
#9 ·
Ok, I'm here now to follow the updates.
Want to do this too
I'll just be boosted and you'll have the 6 speed :kinglock:
 
  • Like
Reactions: t_vago
#13 ·
Got a little more work done on the engine today. Still kind of cold outside, still waiting on all of the parts I ordered, and my garage is not heated, so I am going to wait a little while longer before actually putting together the engine.

However, I do have a few pictures.

upside-down 4.0L engine, Pacifica 4.0L oil pan removed


upside-down 4.0L engine, LX 3.5L 42RLE oil pan temp installed


LX 3.5L inside timing belt cover temp installed


LX right-hand 3.5L engine mount bracket temp installed


LX left-hand 3.5L engine mount bracket temp installed
 
#16 ·
The 4.0L block is almost completely identical to the 3.5L block. The only significant change is that the 4.0L block has larger diameter main bearings than the 3.5L.

The 4.0L cylinder head castings are identical to the 3.5L cylinder head castings. The 4.0L camshafts have more duration than the 3.5L camshafts, and I think they have a slightly higher lift, but they're otherwise a bolt-in part.

Your ported heads and ground cams and ported intake should bolt onto the 4.0L block just fine.
 
#15 ·
Watching this for sure. Watched your 6spd install and loved that. Would like to do it to mine, but I'm not that smart to figure it out.
 
  • Like
Reactions: t_vago
#17 ·
Got a new oil cooler, a bunch of different bolts, and my lower intake manifold today! With luck, I will be doing some more work on my 4 liter block this weekend. I might even port-match the lower intake manifold to the heads...
 
#19 ·
Here's the link to the thread for putting the 4.0 Liter crank in a 3.5 block. I think the 4.0 crank is nodular iron so if your thinking of adding forced induction down the road keep the boost relatively low.

http://www.lxforums.com/board/3-5l-v6-forum/221388-3-5l-stroker.html?highlight=dmondeac
I am not going this route. This information, about grinding down a 4 liter crank to fit a 3.5 block, is interesting in it's way, but it is ultimately irrelevant to my purpose.

The idea here is to show that any LX owner looking to replace their 2.7L or 3.5L, can fairly easily swap in a 4 liter V6 out of a Chrysler Pacifica or a Dodge Nitro. The work required to swap in this 4 liter block is only slightly more that the work that would already be required to swap in a replacement 3.5L engine. All that is really needed is the 4 liter short block, some gaskets from Rock Auto, and possibly a few parts off eBay (which would mainly be for the 2.7 folks).

The LX 3.5L oil pan bolts right up. The LX 3.5L motor mount brackets bolt right up. The LX 3.5L inner timing belt cover bolts right up. I am going to prove this weekend that the LX 3.5L lower intake manifold will bolt right up. My 3.8L manual transmission dust shield holes match the bellhousing bolt pattern on the 4 liter block as they do on the LX 3.5L motor, so I know an LX 3.5L transmission will bolt right up.

The only question I have left is whether the LX 3.5L crank pulley will fit, and I am reasonably certain it will.
 
#20 ·
Seeing as how it's finally warm enough, and I finally have some little bit of free time...

I could bolt the left and right engine brackets onto the 4 liter block. I also verified that the Pacifica crank pulley cannot be used, but the LX crank pulley will bolt on.

Also did some calculations, and figured that either the stock 3.5L fuel injectors will have to flow about 12% more fuel, or I'll have to get a slightly larger capacity set of fuel injectors. The stock 3.5L fuel injectors flow about 246 cc/min, or about 23 lb/hr. To avoid relying on STFT and LTFT, and to avoid relying on tuners that think of V6 tuning as an ignorable afterthought, I would need an injector that flows about 275 cc/min... well, 284 cc/min... Kind of like the fuel injectors I pulled off the 2009 4.7L engine a couple of years ago... The one in my hand has "4591851AA" stamped on it. Looks oddly familiar...

Also looking at different throttle bodies. The 2009 4.7L throttle body is plastic and has an 80 mm bore, which is slightly bigger than the 74 mm throttle opening on the 3.5L intake manifold. That can probably be shaved off with a Dremel tool. However, it has a different wiring pinout than the 3.5L throttle body does. I am going to do some tests to see if it could otherwise be electrically compatible with the 3.5L PCM.
 
#23 ·
Huh... It's been a while since I last posted...

The 4.0L block is in, and is mated to my manual transmission. All engine accessories are installed. Still have to install the lower and upper intake manifolds, install the crank pulley, install the serpentine belt, connect the short headers to the exhaust, fill the oil and coolant, reinstall the clutch slave cylinder, and reinstall the hood.
 
#24 ·
I know I am being bad at this whole updating thing...

The 4.0 is in, and runs great! It's been in since July. There's a noticeable increase in power, though I would not say it's an overwhelming increase. I'd say this was a worthwhile engine swap.

I did have to replace the Centerforce clutch for an Exedy clutch, because the Centerforce became really sticky and would not disengage once the engine would get warm. Also had to replace the driveshaft isolator donut thingies because one of them was starting to fray.
 
#27 · (Edited)
Nope, ended up using the 4591851AA injectors. Been considering going back to my other injectors, the 12 hole 246 cc/min ones, because I do notice that the engine runs a bit rough when it's first started up in the morning, then goes away as the engine warms up. The 12 hole injectors are a lot smoother. This Diablosport Trinity I purchased can apparently adjust WOT fuel delivery.
 
#32 · (Edited)
............ >< A jeep 4.0 is an inline 6 cylinder yo(Unless your talking about a Liberty). A 4.0l out of a Pacifica, Caravan, Liberty, or Nitro is a V6 FYI anyway other than assuming you know what your talking about, which i would fo sho, a 4.0 was most well known as an I6 motor used for many many many years and I have heard that they are bringing it back for a short time. Very well made motor. Especially is you took care of it. Which can be said for most motors with the exception of most of the ECO tec line up from GM which had alot of timing issues.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top