4.7 V8 Liberty

unixxx · **Posted:** Thu Aug 17, 2006 9:24 pm

Ok, this is too cool of an idea to be left alone, so I did a little research.

Note: All of this info applies to 2.4L and 3.7L gas Libertys. I just can't see someone with a CRD wanting to replace their engine. The CRD has completely different engine mount brackets but does already have the correct transmission (at least in my case - MY 2005). The 2006 CRD uses a PCI TCM rather than the 2006 gas's CAN TCM, which could make swapping in a 2006 Dodge Ram CAN TCM more difficult. The CRD BCM is different from the Gas BCM and will probably expect the TCM to be on the PCI bus. In order to use the CAN TCM in the 2006 CRD you'd probably also need to swap out the CRD BCM for a gas BCM.

Emissions:

In order to be smog legal you'll need to use an engine that is the same model year as your vehicle or newer. You'll also need to be sure you install all of the factory emissions equipment that would normally go with that engine.

PCM:

In order for the engine to be compatible with your factory emissions equipment you'll need to make sure you get the same type of PCM (Powertrain Control Module) as you originally had. There are two types of PCMs: JTEC and NGC. JTEC is the older controller and NGC is the newer controller. There's an easy way to tell the two apart: an NGC PCM has four connectors on it because it integrates the TMC (Transmission Control Module), while the JTEC has three connectors on it because it uses a seperate TCM. If you have Sentry Key you'll need to have your VIN number programmed into the new PCM in order to start the Jeep. Simply reprogramming the VIN will create an unerasable DTC, the only way to prevent this DTC is to have the PCM properly reprogrammed using a DRB III so its secret key matches the secret key in your SKIM (Sentry Key Immobilizer Module). You'll want to grab the original PCM and wiring harness when you pick up the engine or you'll be stuck trying to match one later on.

Note: The 2006 Libertys uses a hybrid bus system where the PCM (engine), gas TCM (transmission), and ABM (ABS and ESP) all use the CAN Bus and everything else uses the PCI Bus. The BCM (Body Control Module) acts as a bridge between the PCI Bus and CAN Bus. The 2006 Dodge Ram PCM and TCM also uses CAN, so you might be in luck here.

Engine:

Not that I've done any actual measurements (I can't find any online) but the 4.7L PowerTech V8 is probably the only easily swappable engine that will fit. This engine can be found in the Dodge Dakota, Dodge Durango, Dodge Ram, Jeep Commander and Jeep Grand Cherokee. In my model year, 2005, all of these vehicles except the Dodge RAM utilize the CAN Bus rather than the Liberty's PCI Bus. This means that for the PCM to be electrically compatible with the rest of the Control Modules in my Jeep I have to use an engine out of a Dodge Ram.

Transmission:

All vehicles with the NGC PCM have an integrated TCM, which means that unless you find a way to reprogram it, you're pretty much stuck with the transmission that originally came with the engine. The 2005 Dodge Ram, the only vehicle with an engine compatible with my Liberty, has two transmission options: the 45RFE/545RFE and 48RE. As far as I know, the 48RE is only paired with the Cummins diesels. This leaves the 45RFE/545RFE as the only option. Luckily, the 545RFE should mount perfectly in the Liberty, as it is the same transmission that the Liberty CRD uses.

Cooling:

With the Liberty's relatively small grill and the larger engine, you'll need a more efficient radiator to dissipate all of the heat.

Motor Mounts:

In theory width and height wise the 3.7L should be the same size as the 4.7L. Looking at the service manuals the mounting points on the sides of the two engines look identical. If the 3.7L motor mounts can support the weight of the 4.7L then you should be able to bolt them directly onto the 4.7L and directly into the engine cradle brackets. The 4.7L mounts in the 2002 Grand Cherokee appear to be the same as the 3.7L mounts in our Libertys. The 3.7L wet weight is 422 lbs while the 4.7L wet weight is 474 lbs, making for a weight difference of 52 lbs, which shouldn't pose a problem. Another issue is whether the brackets on the engine cradle can themselves support the wieght of the 4.7L. Luckily, for obvious reasons, the added bulk of the 4.7L is forward of the old engine, so clearance in the firewall area shouldn't be an issue. The hardest part of this swap is definitely the motor mounts, if only because the dimensions and fit aren't known.

SavageSS27 · **Posted:** Mon Aug 21, 2006 6:20 pm

Any thoughts on a pricetag for all that?

unixxx · **Posted:** Tue Aug 22, 2006 12:24 am

The difficult part is finding an engine that matches all of the criteria and includes a wiring harness. Most of the 4.7L PowerTech V8s seem to be going for around $1,700 on eBay. Currently there are no 545RFEs on eBay and the 45RFEs go for $600. Then add a new exhaust, headers, intake, and radiator. You're probably looking at paying at least $4,000 including shipping. Althugh, I'm sure if you visited some junkyards you could do it a little cheaper and you'd be putting new exhaust, headers, and intake on the 3.7L anyways. Apparently a company does make a super charger kit for the 3.7L now and I'd expect it to cost $5,000: http://www.dodgetalk.com/forums/showthr ... light=3.7L

SavageSS27 · **Posted:** Tue Aug 22, 2006 12:29 am

Very true, this is starting to sound more and more feasible, and MUCH more attractive than the 3.7....I might just go all out and get a 4.7 short block, bore it to 5.0 and buy some forged components, etc. Then mount a blower or a turbo, and be more than all set...lol Once i dig up a treasure chest that is...lol

Maximum Carnage · **Posted:** Fri Sep 08, 2006 1:48 pm

I saw a Liberty with a HEMI sticker on the rear window a few weeks ago while in TX. The grill had a screen which wouldn't let me pick in and take a closer look. But is a Hemi engine possible in a Liberty? :?:

unixxx · **Posted:** Sun Sep 10, 2006 2:07 pm

Anything is possible, but I don't think a 5.7L Hemi would fit into the stock Liberty engine compartment. I think the 4.7L PowerTech will just fit.

DarbyWalters · **Posted:** Mon Sep 11, 2006 1:30 pm

When the Liberty first came out, DC actually fit a 4.7L in the KJ as a test vehicle. The biggest problem was that in a headon collision the engine protruded into the passenger compartment...Otherwise the fit was ok. So it can be done.

Seems that someone could stroke the 3.7L and do some head/valve modifications to get some HP. Then find a way to put the 4.7L throttle body on or bore the stock 3.7L throttle body. If you put some beefier pistons/rods in the 3.7L with the rings farther away from the piston crown and maybe slightly lower compression, then a turbo would be an option.

If this link still works below...they had a positve pressure device for the KJ.

http://www.automotionperformance.com/

Well I just looked and they don't have the picks up anymore...They called it the
High Altitude Power Compensator"...I bet they still have a kit or two laying around...I think they had 2 or 3 versions for less or more power.

If the longer CRD will fit...the 4.7 should not be limited by length.

The A Team · **Joined:** Sun Sep 24, 2006 10:38 pm **Posts:** 16

I just picked up my wife's 2006 Limited 4x4 and flipped through a brochure for the '07 Grand Cherokee. On the engine page I saw the same 3.7L V6, 4.7L V8, 5.7L Hemi...and a 3.0L CRD Turbo pushing 215 HP and 376 lb/ft of torque (I remember this because it's 1 more than the Hemi). It's used in Europe and Australia already, see here.

So it got me thinking...3.7L fits fine, a 4.7L *can* fit with some degredation to the 5 star crash test rating, weight distribution issues, suspension droop...forget that! A 3.0L *should* fit fine with a little more HP, a lot more torque, in a smaller package...wow, if I was crazier I think I'd persue this. I know some of you guys are enthusiastic enough to try it. There are some nice V6's out there, but I think this is the best Mopar option.

SavageSS27 · **Posted:** Mon Oct 02, 2006 12:56 am

not only that, but it's a diesel, and if the diesel aftermarket is any indication, i'm sure there's PLENTY of potential in that engine. I'd say (and this is a total n00b's guess) that you could probably have that engine pushing 400HP and 700 ft./lbs. without too much trouble...I mean, it's not uncommon to see guys with diesels that have more than doubled their output through injector swaps, bigger turbos, intakes, exhaust, propane injection, etc. and most importantly, ECU upgrades...you can get an extra 100+hp and 200+ft./lbs. just out of those sometimes...This should definately be a stout little powerplant...i'd love to see one in a liberty...hell, maybe even mine! (keep dreaming Savage)

The A Team · **Joined:** Sun Sep 24, 2006 10:38 pm **Posts:** 16

SavageSS27 wrote:

I'd say (and this is a total n00b's guess) that you could probably have that engine pushing 400HP and 700 ft./lbs. without too much trouble

Somewhere along the line you'd seriously have to beef up the drivetrain. I would imagine 300 HP and 500 ft/lbs would be fairly easy to make with inexpensive mods in a daily driver, but I doubt the trans, shafts, timing chain, etc. would be up to that. 4 Lo would be insane, smoking all 4 would be a sight...you could totally win burnout contests!

KY Liberty · **Joined:** Sat Jul 09, 2005 1:46 pm **Posts:** 1195

I think the conclusion here is that a 4.7 can be squeezed in the Liberty for around $10k provided you already have a 45RFE transmission although it might not be safe in an accident.

Dropping that 3.0 CRD in it is going to be expensive too. If you upgrade it to make 500 ft/lbs of torque, you'll need to put a 545RFE in it with an upgraded torque converter and shift kit in it. I wouldn't count on the rest of the drive train to last long either.

kickit_in4wheel · **Posted:** Fri Oct 06, 2006 9:26 pm

I know we all like our Liberties, but for that kind of hassle and expense, I'd just go ahead and buy the Grand Cherokee CRD and enjoy the warranty that comes with it. The 4.7 thing sounds a bit easier, but still you'd have to be real enthusiastic to make it happen. And we all know enthusiasm is measured in $. Plus, just think how all of us lifted 4X4 guys are gonna feel when that new heavy engine sags out the lift. We still don't have alot of options in the front spring and strut department. I think the new 4.0 V6 might be a good idea, but it will be awhile before a used one is available used. I like KY's idea of just having a quality professional performance rebuild on the 3.7. One day...

Marlon_JBT · **Posted:** Sat Oct 07, 2006 4:32 pm

CRD front springs should help the 4.7L V8's extra weight... use a spacer lift in the front if you're lifted.

REKIII · **Posted:** Mon May 21, 2007 12:24 pm

Just to bring this back from the dead.

I have a 4.7HO from my 02 Grand sitting here with a dropped valve (spring craked, dealer has never seen that before) I'm currently putting in the new longblock that I got from a scrap yard, so when I'm done I'll have this complete engine.

I have an 06 3.7 limited Liberty

Anyways.

What are my computer options? I've done most of my modifying to pre OBDII cars so I don't have a lot of experience with the NGC.

I didn't get any computer with the new motor since I didn't need it. I'm sure I could go find an ECU somewhere.

How do I know which trans is in my libby? It is the 4X4 with the full time 4 wheel option.

So, any opinions? I'm doing the swap in my WJ myself, and have modified other cars quite extensively, so my aptitude is not in questions, but I also like to get other thought and info as much as possible so I'm not reinventing the wheel.

Thanks!!

Bob

tjkj2002 · **Posted:** Mon May 21, 2007 12:40 pm

REKIII wrote:

Just to bring this back from the dead.

I have a 4.7HO from my 02 Grand sitting here with a dropped valve (spring craked, dealer has never seen that before) I'm currently putting in the new longblock that I got from a scrap yard, so when I'm done I'll have this complete engine.

I have an 06 3.7 limited Liberty

Anyways.

What are my computer options? I've done most of my modifying to pre OBDII cars so I don't have a lot of experience with the NGC.

I didn't get any computer with the new motor since I didn't need it. I'm sure I could go find an ECU somewhere.

How do I know which trans is in my libby? It is the 4X4 with the full time 4 wheel option.

So, any opinions? I'm doing the swap in my WJ myself, and have modified other cars quite extensively, so my aptitude is not in questions, but I also like to get other thought and info as much as possible so I'm not reinventing the wheel.

Thanks!!

Bob

AS far as the PCM I'm not totally sure but it would be easier to have the PCM and complete wiring harness from the original vehicle so you should have snagged the PCM and wiring harness when you got the engine.The reason for needing the wire harness from the vehicle is you need the wires for the extra 2 injectors and coil packs,the KJ wiring harness will have to well modified(and probally not worth doing) to work with a V-8 PCM and engine.As far as your '06 tranny,it's a 42RLE and probally not strong enough for a 4.7 V-8,a 45RFE from a '02 KJ will handle the extra power though.

REKIII · **Posted:** Mon May 21, 2007 1:46 pm

I have the engine harness, just not the ECU.

That sucks about the trans.

Well, I still want to keep this as an idea, buying the new 4.7 for the WJ set me back a bit so it will take awhile to fix the old 4.7 and then get the trans. Plus my other money pit project.

Thanks for the input though.

Bob

QuestMan · **Posted:** Mon May 21, 2007 3:11 pm

Do it! Do it! Do it!

Love to hear how it turns out.

KY Liberty · **Joined:** Sat Jul 09, 2005 1:46 pm **Posts:** 1195

REKIII wrote:

I have the engine harness, just not the ECU.

That sucks about the trans.

Well, I still want to keep this as an idea, buying the new 4.7 for the WJ set me back a bit so it will take awhile to fix the old 4.7 and then get the trans. Plus my other money pit project.

Thanks for the input though.

Bob

I know how it feels. I've got a 3.7 short block with 2 scorched cylinders sitting in my garage right now that I'm still trying to decide how to rebuild. Going to be expensive however we rebuild it.

A built 4.7 HO would be really sweet in a KJ. It will be a lot of work, but should be worth it.

Louis Young · **Joined:** Wed Jun 27, 2007 11:21 pm **Posts:** 3

Under an unusual set of circumstances, I happen to have a very, very totaled ‘01 4.7 Dak truck that starts and runs.....I also have a ‘02 Liberty 2WD 3.7 that has dropped a cylinder at 198K miles...(actually maybe two…)..But the body, paint and interior are remarkably clean and serviceable on the Liberty….

Has anyone out there actually done this?? I have both sets of factory service manuals but as you can imagine, that is no help as far as dimensions and such….I wonder if the jump from 210HP & 235 ft lbs to 250HP and 300ft lbs would be worth the time and energy….40 hp and 65 ft-lb’s……Hmmmmmm……

I understand the engine controller and engine harness may plug and play…maybe….Would the hood close?? the accessories and accessory drive looks compatible….I suppose the tranny could just follow the 4.7 right out the front of the dak and into the Liberty as an assembly..….I guess the tailshaft housing is the same ?? ….

Gentlemen….Has anyone actually done this??

unixxx · **Posted:** Thu Jun 28, 2007 2:14 pm

There's no replacement for displacement; throw a supercharger on the 4.7L :twisted:

Louis Young wrote:

I wonder if the jump from 210HP & 235 ft lbs to 250HP and 300ft lbs would be worth the time and energy….40 hp and 65 ft-lb’s……Hmmmmmm……

4.7 V8 Liberty

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