Go Back   Jeep Garage - Jeep Forum > Jeep Platform Discussion > Grand Cherokee - WJ > Engine Performance/Intake/Exhaust

Join Jeep Garage Today
Reply
 
Thread Tools Display Modes
 
  #1  
Old 01-03-2012, 11:01 AM
Member
 
Join Date: Jan 2012
Posts: 12
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 985
jrwhit04 is on a distinguished road
2003 4.7L Engine Decision

So, I purchased my first WJ from my brother, it's a 2003 Limited with the 4.7L V8 and the Quadra-Tac 4x4 system. When I bought it, I KNEW it had a blown head gasket, so I was well aware that repair was necessary, and it was why I got it for so cheap in the first place.

This weekend I finally dug into the beast, and sure enough, the head gasket was blown but I also found cylinder's 7 and 8 were scuffed. They were "lightly" scuffed, but no matter how hard I try, I just can't ignore the fact that they are indeed scuffed.

This brings me to my question, and that is where do I go from here? As I see if I have several options:

1. Rebuild the engine I have (assuming block and heads are not cracked)
2. Get a junk yard engine that's running with low miles
3. New engine, or newly rebuilt engine

Also, I would "like" to have the HO engine, and based on threads I read, it is possible, and not that difficult. I am looking for any advise, or recommendations on which option, AND if the HO conversion is worth it in the long run. Thanks in advanced.

- Robbie
__________________

__________________
Reply With Quote
  #2  
Old 01-03-2012, 03:04 PM
Member
My Jeep: 2004 4.7 HO WJ
 
Join Date: Jan 2011
Location: Fortville, Indiana
Posts: 107
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 1417
Me Fix is on a distinguished road
Re: 2003 4.7L Engine Decession

Why do you want the HO engine? Lots to think about here!

Two bad cylinders suggests a complete rebuild. It can be very hard on other parts after fixing up two cylinders. It's like doing a valve job and then having renewed pressure on all the main bearings and piston rings. I always found it better to just rebuild the whole thing. Once you get things apart, you can take the major parts to a machine shop. They will check everything, straighten up the cylinder walls, polish the crank journals, set you up with new rings, do a complete valve job with new seals. All you would have to do is clean up all the other parts and brackets and put it all back together, if you are that kind of guy. We got 350,000 out of an old astro mini van before I rebuilt the engine ansd had the transmittion serviced. We then got another 100,000 or so before we traded for a new one. That ended up being a mistake, because the new one become a nightmare. One of those, "I'll never have another one of those" vans.

Your looking at least a different ECM and program with the HO engine.
__________________

__________________
Reply With Quote
  #3  
Old 01-03-2012, 03:20 PM
Member
 
Join Date: Jan 2012
Posts: 12
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 985
jrwhit04 is on a distinguished road
Re: 2003 4.7L Engine Decession

I want the HO simply because it's "cooler".........sounds kinda dumb when I say it like that, but honestly, I can't come up with a better answer. Simply more power and torque, which I generally like!

So your vote is rebuild...... interesting, my buddies are saying the same thing....

I have looked at wjjeeps.com and see the differences in the HO and non-HO. The one thing that isn't clear to me is if it is possible to mount the knock sensors to my non-HO block. Assuming I got the HO crank, HO rebuild kit, complete HO cylinder heads and intake, could I make my non-HO an HO or is there a difference in the actual engine block that would prevent this?

Thanks again for the advise, I will post which direction I end up going in.....
__________________
Reply With Quote
  #4  
Old 01-03-2012, 04:37 PM
Member
My Jeep: 2002 4.7 HO WJ
 
Join Date: Jul 2011
Location: Australia
Posts: 26
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 1175
JeepNut is on a distinguished road
Re: 2003 4.7L Engine Decession

How about since you should rebuild and thinking of a HO why not do your block .....go a stroker kit a port and polish HO cams and a late manifold. Now that cool! Money permitting of cousre
__________________
Reply With Quote
  #5  
Old 01-03-2012, 05:10 PM
Member
My Jeep: 2002 4.7L WJ
 
Join Date: Dec 2011
Location: Long Island NY
Posts: 9
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 986
wjgiants39 is on a distinguished road
Re: 2003 4.7L Engine Decession

I would rebuild the one you got and get H.O. cams and a newer 4.7 intake manifold and go from there with whatever else you feel needed, might as well work with what you got
__________________
Reply With Quote
  #6  
Old 01-04-2012, 07:21 AM
Senior Member
 
Join Date: Jul 2009
Location: Scotland, UK
Posts: 1,878
Thanks: 20
Thanked 15 Times in 15 Posts
Rep Power: 79933
Martyp has a reputation beyond reputeMartyp has a reputation beyond reputeMartyp has a reputation beyond reputeMartyp has a reputation beyond reputeMartyp has a reputation beyond reputeMartyp has a reputation beyond reputeMartyp has a reputation beyond reputeMartyp has a reputation beyond reputeMartyp has a reputation beyond reputeMartyp has a reputation beyond reputeMartyp has a reputation beyond repute
Re: 2003 4.7L Engine Decession

I'd say rebuild what you have and it would be the perfect time to install some HO cams or a regrind with new springs etc, 08 intake manifold + TB converter and get your TB ported (or buy a ported one) then install a 180 t-stat. Then get a SCT tuner and custom tune for it.

If you have enough to sink into it, you could bore it out a little, new pistons or fit a stall converter etc. etc.

Have a look on www.airram.com and/or PM him on here. He is really helpful and is one of the main places to get 4.7 goodies.
__________________
Marty

"Even though I walk through the valley of the shadow of rice, I will fear no turbo for thou torque art with me. Thy rods and crankshaft, they comfort me."
Reply With Quote
  #7  
Old 01-04-2012, 09:17 AM
Member
 
Join Date: Jan 2012
Posts: 12
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 985
jrwhit04 is on a distinguished road
Re: 2003 4.7L Engine Decession

Sweet website, thanks Marty for the recommendation. It would appear that a rebuild is pretty much the consensus, both from this forum and pretty much everyone I talk to. Now I have to figure out what I can afford as far as a rebuild goes.

I do have another question, and that is about the crank. From what I gather, my NON-HO engine doesn't have a forged crank, and an HO does. Is it worth getting the forged crank if I am planning mild upgrades, like you mentioned above?

Thanks again for all the advise, I am new to the 4.7L world, so this is a learning experience for me for sure. If this Jeep was the standard 4.0L inline 6, I would be much more in my comfort zone!

- Robbie
__________________
Reply With Quote
  #8  
Old 01-04-2012, 09:42 AM
Senior Member
 
Join Date: Jul 2009
Location: Scotland, UK
Posts: 1,878
Thanks: 20
Thanked 15 Times in 15 Posts
Rep Power: 79933
Martyp has a reputation beyond reputeMartyp has a reputation beyond reputeMartyp has a reputation beyond reputeMartyp has a reputation beyond reputeMartyp has a reputation beyond reputeMartyp has a reputation beyond reputeMartyp has a reputation beyond reputeMartyp has a reputation beyond reputeMartyp has a reputation beyond reputeMartyp has a reputation beyond reputeMartyp has a reputation beyond repute
Re: 2003 4.7L Engine Decession

Sorry but you can't get the forged crank anymore... Airram listed on their site last time I looked but Mopar now just offer one crank. Whether you get a forged or non-forged is a lucky dip I think.

To be honest though, I don't think its all that important unless you are going to add a lot of boost or NoS to the motor.

Getting the ARP stud kits for the motor would be a good idea though. Although if you speak to Nick @airram he'll tell you what you'd need to keep it safe.
__________________
Marty

"Even though I walk through the valley of the shadow of rice, I will fear no turbo for thou torque art with me. Thy rods and crankshaft, they comfort me."
Reply With Quote
  #9  
Old 01-04-2012, 11:44 AM
Member
My Jeep: 2004 4.7 HO WJ
 
Join Date: Jan 2011
Location: Fortville, Indiana
Posts: 107
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 1417
Me Fix is on a distinguished road
Re: 2003 4.7L Engine Decession

What about going to the junk yard and maybe finding an WJ with and HO engine. If you were lucky, you might be able to get everything needed to simply replace what you have now. Or if you can find an HO engine and related parts, you could do a rebuild on that before you install it. Either way you go, you're going to be spending some bucks. Don't take this wrong, but is your Jeep worth it? It is possible to spend more than your ride will be worth after you get done!
__________________
Reply With Quote
  #10  
Old 01-04-2012, 02:06 PM
Member
 
Join Date: Jan 2012
Posts: 12
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 985
jrwhit04 is on a distinguished road
Re: 2003 4.7L Engine Decession

Ha! My thoughts exactly....is this worth it?

Here's what I have come up with, the Jeep is in great shape cosmetically, I got it for hardly anything, so even with investing $2000 or $3000 in an engine, I will have less in it than it books for (but damn close). I plan on driving the wheels off this thing, so yeah, it's worth it to do it right so I don't have to do this again.

I have been doing some looking around and I have a lead on a running HO engine with 74k on it. They want $2100, and will work in a 3 year warranty for $200 extra.

Due to the fact that I am having trouble finding someone with HO cam's in stock, and as Marty informed me, I can't get a forged crank........I am leaning towards getting this HO engine and "freshening" it up a bit with new gaskets, possibly new timing chains/tensioners, and a new oil pump and calling it good.

Thanks to everyone for their thoughts and advise, it is most appreciated.

- Robbie
__________________
Reply With Quote
  #11  
Old 01-04-2012, 03:25 PM
cheapjeep's Avatar
Amber Instigator
My Jeep: 1997 2.5L TJ
 
Join Date: Sep 2010
Location: Vintondale Pa.
Posts: 3,101
Thanks: 97
Thanked 68 Times in 64 Posts
Rep Power: 331899
cheapjeep has a reputation beyond reputecheapjeep has a reputation beyond reputecheapjeep has a reputation beyond reputecheapjeep has a reputation beyond reputecheapjeep has a reputation beyond reputecheapjeep has a reputation beyond reputecheapjeep has a reputation beyond reputecheapjeep has a reputation beyond reputecheapjeep has a reputation beyond reputecheapjeep has a reputation beyond reputecheapjeep has a reputation beyond repute
Garage
Re: 2003 4.7L Engine Decession

In the interest of keeping you from getting in way over your head there are some serious points to consider.
1.The most important.Since your GC is an '03 you are in the "grey" area concerning engine management systems. It could be jtech or ngc. If you don't have the jtech system forget the HO unless you feel like gutting most of your vehicles original wiring harness and are a Mopar wiring guru. Jtech has the separate tcm mounted by the overflow bottle. If you dont have this its ngc.


2.If you read jeepwelds stickie you'll see he still had considerable obstacles to overcome even going 4.7 jtech to 4.7 jtech.This could possibly be to the fact that he was putting an HO into a GC that was built before this engine was around or maybe not.They may have made provisions in the later harnesses for both or possibly not. If not you have quite a few sensors issues ahead.
3.If you use your ecm that came with your Jeep you will need a custom tune and a tuner that supports them.If you use the Ho ecm your gonna have it towed to the dealer to have it programed for your key because it won't run for more than 4 seconds.
4. I'm not trying to discourage anybody,I'm all for performance,but it's good to know what you're getting into beforehand.
__________________
Dave'04 Overland,I don't even remember what I did to it anymore.

Quote:
Originally Posted by TJXJWJ View Post
OK, fine...I'll admit...some amber lamps are good, and necessary.
Reply With Quote
  #12  
Old 01-04-2012, 03:47 PM
Member
 
Join Date: Jan 2012
Posts: 12
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 985
jrwhit04 is on a distinguished road
Re: 2003 4.7L Engine Decession

Dave,
Thanks for the detailed response, it is much appreciated. I am especially glad you sent the picture, because I had read about the JTEC, non-JTEC issue on this board and many others, and based on what I was reading I "thought" I had a JTEC vehicle. Since my jeep has what you showed in the picture, this further confirms what you said about it being JTEC.
I might be optimistic, nieve, stubborn, or some combination there of, but I am "hoping" that the sensor issues encountered by jeepweld won't be as much of an issue for me since my vehicle was made when the HO was available as an option. Also, if I do encounter the issues, luckily I can learn from his experience and at least know which direction to head in trouble shooting. This might be silly, but it's a risk I just might be willing to take.

And about getting in over my head.....I'm a mechanical engineer by trade, so even if I get myself in over my head, I probably won't admit it!

Also, my daily drive is a 1984 Chevy truck with a Cummins engine out of a 1989 Dodge and a NV4500 transmission from a 1998 Chevy truck. While I might be new to the 4.7L world, I am familiar with engine swaps, and running engines in vehicles that the factory didn't put them in.

I am sure there will be PLENTY of unforeseen obstacles if I decide to go the HO conversion route, but the more I think about it, the more I think I might just have to do it.....

Thanks again for all the help, it really is appreciated.

- Robbie
__________________

__________________
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Help me make a decision... Crestwood1001 Grand Cherokee - WK 9 08-21-2011 08:59 PM
Final Decision!!! Airbags!!! SoCalMoparWK Performance Modifications 31 08-11-2009 11:05 AM
finally made my decision!!!!!!! BUDAKANE Performance Modifications 24 07-05-2009 08:28 PM

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 12:55 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Copyright 2012 - JeepGarage.Org
The Jeep Grand Cherokee Owners Community