Chrystler PowerTech Block Q? (Old "LA" thread)

SavageSS27 · **Posted:** Sat Feb 24, 2007 1:31 am

I was looking around for a good 4.7L short block to do a V8 conversion, when someone mentioned something to me. I was under the impression that the 4.7 was probably the most engine I'd be able to squeeze under the hood of the KJ. But this person said something to the effect of "even thought the 4.7, 5.2, and 5.9 are all different on the inside, i think they use the same block." Under this mode of thinking, it would make sense to assume that since they all use the same block, just different bore/stoke, i could just jump right to a 5.2 or 5.9. If anyone has the exterior specs of the three engines in question i would greatly appreciate it. Not to mention any links where i might be able to find an inexpensive short-block.

Thanks

unixxx · **Posted:** Sat Feb 24, 2007 2:12 am

The problem is that the PowerTech series is different from the now discontinued (except V10) LA series. While they could use the same block, I have feeling that they probably don't. Wouldn't it be sweet if they did.... :twisted:

Let me check to see if I can find any engine specs for you.

swyszomirski · **Joined:** Sat Oct 01, 2005 2:59 am **Posts:** 286

This has the makings of an HISTORIC Tech Article! Please keep us informed.

Stephen

tjkj2002 · **Posted:** Sat Feb 24, 2007 11:29 am

The 5.2 and 5.9 are totally different engines(they have been around for many a years)than the 4.7.The biggest problem is your tranny,it won't handle the power of the 4.7(the 4.7 HO will eat it for breakfast),so you will also need to swap in a different tranny.Alot of electronic work is needed to make it run.I on the other hand have the beefier tranny and I'm on the hunt for a '99-'02 grand/durango/dakota that has been wrecked just in the rear for cheap.Not only do I need the engine but the PCM and engine wiring harness intacted,but finding on for cheap and only wrecked in the rear without a million miles on it is proving pretty hard.

TheJawsOfDeath · **Joined:** Sun Nov 05, 2006 3:56 am **Posts:** 305

Other than the fact that they are all V8s, the 4.7 shares nothing with the 5.2 (318) and 5.9(360) V8's. Main difference lies in the valvetrain. Whereas the 4.7 has single overhead cams, the LA V8s are overhead valve/pushrod. Heres a good article to read.

http://www.allpar.com/mopar/47.html

Hope that helps.

SavageSS27 · **Posted:** Sat Feb 24, 2007 7:44 pm

OK, so after some more digging and head scratching, it turns out i was mistaken. Like Unixxx, tjkj and Jaws said, the LA series is much different from the PowerTech (Magnum) series. First and foremost, the LAs are pushrod engines, and the PowerTechs are SOHC. Also, the LAs had a 4.66" bore spacing, the PowerTechs now have only 4.09". So that means I wont be able to bore the 4.7 out as far as i had hoped. Here You can see what someone did to one by boring it out and adding a Kenne Bell supercharger. That's pretty much what i'm aiming for, but if i can get more cubes to begin with, then that's never a bad thing. Unfortunately, the end of the video (the part with the actual driving) seems to not be working.

So if any of you guys have compatibility information, such as PCM (I thin the 3.7 and 4.7 are the same) Transmission (I think the 545Rle is my best bet), etc. I'd appreciate it. I'm sure KY Liberty is around here somewhere and i know he's looked into this before. I just hope he'll chime in with some pearls of wisdom.

I plan on doing as much of the work as possible myself while i'm away at WyoTech. I figure i should be able to pass is off as a school project or something, even if i just have to sneak into the shops after-hours. The idea is that i'll build the motor and get it tuned up on an engine dyno, then shoe-horn it into the KJ. After that gets all worked out, or maybe at the same time, the rest of the drivetrain will get an overhaul, including a SAS capable of 33s. i've got big plans for my little KJ and i don't intend to half-@$$ it.

Guess i might as well change the name of the thread to "Chrysler PowerTech Engine Block Question" :lol:

I'm open to any imput, i want to do this right the first time, so i don't intend to cut any corners. I'd like to get anywhere from 450-500HP out of this engine, so everything is gonna have to be pretty stout. I might even open a website and start taking donations to the cause. I figure for every $10,000 i get in donations, i'll go out and buy a beater...and crush it with the KJ (in whatever stage it's in) and then post the video on the net. That should keep the non-believers quiet. :twisted:

unixxx · **Posted:** Sat Feb 24, 2007 7:58 pm

The 545RFE is a good choice as it sits behind both the Liberty's 2.8L diesel and the Ram's 5.7L Hemi. Since the TCM and PCM are combined, your best bet is to grab a 4.7L from a Ram, already paired with a 545RFE tranny. Earlier, KY Liberty posted that a larger engine may enter the passenger compartment in an accident

Which would suck.... Don't forget to add an Atlas transfer case and Dana 44s to your plans. Then, you could quite possibly have the sickest Liberty ever built :twisted:

SavageSS27 · **Posted:** Sat Feb 24, 2007 8:05 pm

Cool, thanks for the tip on the TCM/PCM thing. I'll start looking for a wrecked Ram with a 545 and a 4.7. I'm not too worried about the engine/passenger compartment issue. I'm not saying i won't hit anything, but in the event that i do, i'll most likely just drive right over it. :twisted:

I was planning on the Atlas and maybe even some 60s. I've heard that 33" is about as big as you want to go on 44s, and i'm planning on putting A LOT of power to the ground. Besides, the extra weight of the 60s will keep all 4 on the ground in off-camber situations and, god forbid, evasive maneuvers. :shock:

But if the 60s are overkill, LMK, i don't want to skimp on anything, but i'd also like to keep the money i don't HAVE to spend.

unixxx · **Posted:** Sat Feb 24, 2007 8:18 pm

The problem is that the larger axles remove ground clearance. The Ram Power Wagon (3/4 ton), which has the 5.7L Hemi and 545RFE, has a Dana 70 rear axle. Since the SRT10 Ram is 500 hp, it would be interesting to see which rear axle it uses. I'd say at least go with 44s, after that you've got 60, 70, and 80. The GM 14-bolt is also a popular option among the hard core crowd. Heck, you could even buy a Spider 9 axle from Spidertrax. If you get this project off the ground, please take lots of pictures and do a massive write up. I've been looking into something like this for a while :twisted:

SavageSS27 · **Posted:** Sat Feb 24, 2007 8:21 pm

Dont you worry, if this works out, i'll take enough pictures to fill up Photobucket and write enough to clog up Wikipedia. But something just occured to me. If i'm swapping out the TCM and PCM anyway, and the BCM is a separate module, why go with a 4.7, why not a 5.7 Hemi, or even an EFI crate motor?

tjkj2002 · **Posted:** Sat Feb 24, 2007 8:26 pm

A 4.7 will fit in our engine bay but it'll be really tight(custom raditor and fan).Have you seen the size of the 5.7 Hemi? Good god,you'll have to cut half the front end off to get it to fit,length wise it's fine but width wise you got some major problems.Though it would be awsome to have a Hemi, "does that thing have a Hemi? Why yes it does(will roasting the tires)".

unixxx · **Posted:** Sat Feb 24, 2007 9:16 pm

No crate motors and only street engines from the vehicle year or later are emissions legal. The engine and computer also need to be able to use all of the gas and exhaust emissions equipment. Of course, some states don't have emissions testing, but mine does.

There are aftermarket fuel injection and ignition controllers to replace of the PCM and I don't think it would be that difficult to build a custom board to replace the TCM.

OzLtd · **Posted:** Sat Feb 24, 2007 9:56 pm

heck, i've thought of this one as well, but i'd rather get the 3.0 V6 CRD WK Grand motor in there and chip it to 195Kw / 600Nm

The 4.7lt Powertech from the WG/J Grand is the only V8 I thought would ever fit into the KJ's motor box area.

Go you good thing !! Lets see a V8 !!

SavageSS27 · **Posted:** Sat Feb 24, 2007 9:59 pm

OK, so basically i need a 4.7 out of an 03+ Ram? darn, that doesn't sound cheap. Oh well. Looks like i need to make some phone calls and some REALLY long lists.

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

SavageSS27 wrote:

OK, so basically i need a 4.7 out of an 03+ Ram? darn, that doesn't sound cheap. Oh well. Looks like i need to make some phone calls and some REALLY long lists.

You're going to need the transmission and some programming too. I would love to see someone with a V8 Libby, but you can build the 3.7 and the current transmission to easily outperform the stock 4.7 for a lot less money. I would recommend multiple smaller projects to attain a KJ that will make everyone reach for something to hang on to. Since you're going to be doing it at Wyotech, you need to go to 4.10 gears, which will give you experience with differentials. You need an upgraded torque converter, and a shift kit to get experience with transmissions. You need some 206 cams, forged pistons and rods to get experience building a long block. You need to port the heads to learn to do machine work. You need to get a spare PCM programmed by B&G so you can learn about the security built into the VIN and sentry keys. Just keep up the pattern, and don't forget to make the suspension handle the power, and the brakes able to stop it. :wink:

SavageSS27 · **Posted:** Sat Feb 24, 2007 10:40 pm

I was wondering when you'd chime in :lol:

But i'm not looking for something that'll outperform just a plain-jane stock 4.7. Unless i can get 500 reliable HP out of the 3.7 without spending a fortune, it's gone. There's no replacement for displacement. And like i said before, the whole drivetrain is gonna go. So that means Computer, Tranny, Trans Case, Axles, and Engine. I'll be building the 4.7 myself (boring it, building it and possibly supercharging) The 545 will most definitely get a shift kit, becasue i shure as hell won't be putting 500 ponies through a stock one (not that it won't handle it, i just want it to last). The Tranny case is gonna get upgraded, and the axles will probably be swapped to 44s. Basically, i'll be building Wally's KJ, but with a V8 in it. I have plans to build my own tube bumpers, tubular fender flares, interior and possibly exterior cages, custom seats and interior, new paint, etc, etc. I'll probably be able to do all the tuning work at wyotech, so that will get my the experience on the keyboard end as well. This is something i've been thinking about for a while. I want to pull out all the stops, and i want to do as much as possible with my own two hands.

tjkj2002 · **Posted:** Sat Feb 24, 2007 10:59 pm

Quote:

There's no replacement for displacement

AMEN!!!!!!!!!!!!!!!!! Got a buddy back home with a 640 cu in wedge motor that puts out 900 HP on pump gas,now that would be fun in a KJ!!!!!!!!!!!!!!!

SavageSS27 · **Posted:** Sat Feb 24, 2007 11:07 pm

Lol, maybe i'll just put the engine in the back half. Then i'll have as much room as i can use... :lol:

unixxx · **Posted:** Sat Feb 24, 2007 11:11 pm

Quote:

There's no replacement for displacement

Well said

Quote:

Lol, maybe i'll just put the engine in the back half.

Throw the engine in the trunk, install a firewall, and throw all of your tools under the hood :lol:

But then you'd have to put the gas tank in the front and you wouldn't have any air flow.

The 2002-2005 Ram is the only vehicle I can verify to have a PCI bus JTEC PCM :shock:

The 2002-2004 Grand Cherokee uses the PCI bus, but I'm not sure whether it's has a JTEC or NGC PCM. Newer Libertys need the NGC controller for emissions and you can't just swap computers because the NGC engines have a different crankshaft reluctor wheel. JTEC engines have 16 teeth on the wheel and NGCs have 32. I believe the change from JTEC to NGC began mid 2002. Check out this thread for more info:

http://www.lostjeeps.com/forum/phpBB3/vie ... 2&start=47

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

That's going to be a ton of work, but it's going to be sweet. I think that you'll be closer to 400 hp with the 4.7 and supercharger. Going to be hard to get 500 hp out of it. Considering what a wild ride 335 hp and 400 ftlbs torque was in mine when I was racing it, 400 hp all the time should be amazing. :shock:

Chrystler PowerTech Block Q? (Old "LA" thread)

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