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Unread 09-10-2003, 07:51 PM   #1
Bob K
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Has anyone chipped the 4.0?

I am shopping for a GC and can't decide between the V8 and the 4.0. Virtually everyone who answered my poll said "buy the V8". I'mm wondering if a performance chip can give it that little extra bit of torque that would make the difference towing and on long hills.

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Unread 09-10-2003, 08:15 PM   #2
Brian's 97 ZJ
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From what I've heard, the performance gains (or loss!) is not really worth the $ they are asking for them. At least, you would have to modify your intake and exhaust system to get the full benefit.

Others on this board can certainly advise. Anyone?

- Brian
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Unread 09-10-2003, 09:16 PM   #3
Skyjacked97ZJ
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All the chips available for the 4.0 suck. Most make you lose power. In fact chips for most cars don't do much of anything unless your already modded, then it just optimizes the computer for your mods. If your gonna tow, get a V8, if not I6 is pretty sweet. The only thing that's gonna make a 4.0 tow like a V8 is a blower or a stroker kit, and honestly it's easier to just buy the V8. Better aftermarket engine parts for the V8 too.
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Unread 09-10-2003, 09:18 PM   #4
MichiganK9SAR
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I usually find that engines come from the factory tuned to the best configuration. This best is usually in the form of a compromise between long service life, fuel economy, and power. Ready-made replacement "performance" chips do things to make it appear that you have better performance. These things include changing fluid pressures in automatic transmissions, decreasing shift times in automatic transmissions, increasing the rev limit. All of which will decrease the life of your engine.

Performance chips are not made to provide smooth power curves, or low-rpm torque that is necessary for off-road vehicles and towing. To adapt a chip for these uses, one would have to burn their own chip.

While it might sound fun to burn your own chip, I would recommend against anyone fiddling with ECM values unless they really knew what they were doing. Consider the ramifications of something as simple as decreasing the spark timing. You will need to use higher octane gas. The question being, how much higher? You will probably need cooler plugs, but how cool? You will probably need to adjust spark plug gaps, but how much? You may need to adjust air/fuel mixture...well you'll need to reburn your chip for that:

And once you're into adjusting air/fuel mixture, you'll find that you'll need to find a balance within the limitations of your intake and exhaust.

Now there are a few things you can do to an ECM that aren't much a big deal. For example, you can probably get away with lowering the fan temperature limit without getting into much trouble. However, when it comes to engine performance, there exists a balance that even in modification needs to be struck.

IMHO, not worth the trouble. If you legitimately need the V8, buy it. Don't send an I6 in to do a V8's job.

Last edited by MichiganK9SAR; 09-10-2003 at 09:21 PM..
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Unread 09-10-2003, 09:42 PM   #5
Bob K
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Thanks so far guys. That's what i thought. I used to frequent the Bimmer 6 series board and the more knowledgeable guys said pretty much the same thing. Basically the laws of physics can't be beaten by a chip ie you can't get something without sacrificing something else somewhere. The factory engineers get paid big bucks to figure it all out. Aftermarket companies can't afford the R&D time involved in designing something better than what the factory did.
But Iwas still hoping to get a different answer.
Any other experiences or opinions I'd still like to hear.
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'87 Wrangler YJ 4.2 I6 (sorry, sold)
JuiceBox ignition
2 1/2" ProComp Lift
31" BFG A/T's
K&N Filter
Custom Rock Guards
Turbo Muffler
Rear Track Bar in the shed
Other Tricks I won't tell to just anybody!

'99 Grand Cherokee 4.7 V8
Towing Package
K&N FIPK
ProComp MX6 shocks
Borla Exhaust
Tow Hooks
Alpine CD with Infinity+iPod connect
Just getting started!

If you're not living on the edge...
you're taking up too much space.
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Unread 09-12-2003, 12:20 PM   #6
jeepme79
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I've had both, and they are both great engines, but it still comes down to what you want to do with it. If you plan on frequently towing anything larger than an ATV, then you are probably better off with the V8. Otherwise, the I6 will tow anything you need. As a daily driver, I would suggest the I6. The only advantage the V8 has in this case it more speed, but that's not what most people drive Jeeps for. The mileage in the V8 in town sucks, and the highway isn't much better. My best tank in my 5.2 is still lower than the worst tank in my old 4.0 with over 200k miles on it. IMO, the 4.0 is will also last longer, and in general is easier to work on.

As an example, I towed my brother's 17' ski boat with my 4.0 for 100 miles round trip, and still got 16.5 mpg for the trip. Towed the same boat with the 5.2 on the same 100 miles and got 11.5. The 4.0 did the job just fine, but the 5.2 did it a little easier.
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Unread 09-14-2003, 03:22 PM   #7
10achik
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Dude, let me save you a lot of money, I did the same thing your talking about. I had a 98 GC with the 4.0 and I loved it, but it lacked the real power I wanted...so what did I do, I added the JET chip (on the 4.0 it's just about worthless), then I added a drop in K&N fliter. I'm guessing it may have added a little, but still not what I wanted. After a lot of soul searching, I went an traded in on my current GC (listed below) and havent regreted it a day yet! This V8 with the mod's I've added to it makes it an absolute beast!!! nothing like blowing past the ricers in their 4 and 6 bangers w/ the "fart can" mufflers.

So save yourself the headaches and money and just go with the big dawg!
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99 GC Limited - 4.7L HO V8, 6.5" IRO HC LA lift, F&R D44s locked & trussed, 242HD, IRO TC Skid, KMA Bumper, 35's
2006 Saturn Redline -2.0L Eaton supercharged I4, GMPP Stage 2, Custom Tune, AEM CAI, Ebiach Pro Kit w/ swaybars, EVO Ventus V12s (13.76 @ 103.85)
2006 Pontiac G6 GTP
2012 Nissan Juke - (hers)
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2006 Triumph America 900 - Full Dresser

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Unread 09-14-2003, 10:55 PM   #8
Bob K
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thanks i0achik, Just the kind of answer I was looking for. I think the HO's are rare. But I'll definitely be shopping for the 4.7.
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'87 Wrangler YJ 4.2 I6 (sorry, sold)
JuiceBox ignition
2 1/2" ProComp Lift
31" BFG A/T's
K&N Filter
Custom Rock Guards
Turbo Muffler
Rear Track Bar in the shed
Other Tricks I won't tell to just anybody!

'99 Grand Cherokee 4.7 V8
Towing Package
K&N FIPK
ProComp MX6 shocks
Borla Exhaust
Tow Hooks
Alpine CD with Infinity+iPod connect
Just getting started!

If you're not living on the edge...
you're taking up too much space.
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Unread 09-15-2003, 09:27 AM   #9
ecrab3
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I like to add to the numbers by saying to skip on the chip as well. I also have a 98 ZJ 4.0 that I added a Jet chip stage 1 to it, along with Jacobs wires, plat plugs, K&N drop in filter and a Dynomax catback around 10,000 miles.
The chip was the only mod that really wasnt worth the bucks. ON top of it all, I need to run 92+ octane to get the chip to respond, it really only allows the engine to rev higher and longer. Not that good of an idea.
Needless to say I run 89 octane now and dont even notice the chip anymore.

If I had to do it all again, I should of bought a V8 in 98 instead for the seat of the pants thrill, but then again my ZJ runs and looks like new and its paid for, I think if I had a V8, it would of been dogged out by me. So its all good
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Unread 09-15-2003, 10:06 AM   #10
jeepme79
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I have the Jet Stage II in my 5.2, and I did notice a little difference around 3000 RPM, but not worth the price of a new chip.
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98 ZJ Limited, 5.2L, NP242, Jet Stage II (worthless), K&N, 245/75-16 BFG KO's
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79 CJ7 - Options included ripped soft top, leaky 4.2L (5qts/week), ripped seats, 33" tires, bondo & gray primer
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Unread 09-20-2003, 02:36 PM   #11
Rockhound79
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Bob K those guys have great advice. If you don't need to pull big, don't buy the V8. For a minor speed increase you're sacrificing valuable mpg. Seriously, are you getting a V8 GC so you can be faster than a 2000 lb V6? I don't remember seeing GCs in the fast and the furious.
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Unread 09-20-2003, 04:42 PM   #12
10achik
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Quote:
Originally Posted by Rockhound79
Bob K those guys have great advice. If you don't need to pull big, don't buy the V8. For a minor speed increase you're sacrificing valuable mpg. Seriously, are you getting a V8 GC so you can be faster than a 2000 lb V6? I don't remember seeing GCs in the fast and the furious.

FYI, Its a straight 6, and I had one in my 98 GC before I got this one and the mpg was about the same. As for the Fast and the Furious, I'll take on a ricer anyday - unless they got a large turbo and NOS, they aint touching my GC...

Just from the mods I got, I'm running 14.3 in the 1/4 @ 101 mph. Don't be fooled by the "big sleeper"! Hollywood's all about the imports, becuase GC's aren't known for their great speed, doesn't mean they aren't fast.

I'll go back to what I said before, BUY THE V8!!! Because if you ever get the pleasure of driving the V8 after you already bought the 4.0 straight 6, you will definately regret it. I know I did and I paid for it.
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99 GC Limited - 4.7L HO V8, 6.5" IRO HC LA lift, F&R D44s locked & trussed, 242HD, IRO TC Skid, KMA Bumper, 35's
2006 Saturn Redline -2.0L Eaton supercharged I4, GMPP Stage 2, Custom Tune, AEM CAI, Ebiach Pro Kit w/ swaybars, EVO Ventus V12s (13.76 @ 103.85)
2006 Pontiac G6 GTP
2012 Nissan Juke - (hers)
2000 SV650 - naked, integrated tail light, sliders, corbin, pilot roads, RK chain & sprokets, D&D full exhaust, FactoryPro Stage I jet kit, +4 Ignition Advancer, Barnett race clutch
2006 Triumph America 900 - Full Dresser

January 2009 Grand Cherokee of the Month (GCOTM)
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Unread 09-20-2003, 06:54 PM   #13
Ross
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I got the six. Power is fine for me but it is not a race car or a towing machine. It is not underpowerd.

The reasons I got the six was the dependablity of the motor. I don't know about the newer grands but the all wheel drive tcase you get with 8 can wear out. The six you can get a tcase that you can take out of 4 wheel drive. Plus the mileage. I get about 17 in town and just over 20 on the highway.

Ross
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Unread 09-20-2003, 08:07 PM   #14
10achik
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I get similar mpg when I can keep my big foot out of it
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Ken

99 GC Limited - 4.7L HO V8, 6.5" IRO HC LA lift, F&R D44s locked & trussed, 242HD, IRO TC Skid, KMA Bumper, 35's
2006 Saturn Redline -2.0L Eaton supercharged I4, GMPP Stage 2, Custom Tune, AEM CAI, Ebiach Pro Kit w/ swaybars, EVO Ventus V12s (13.76 @ 103.85)
2006 Pontiac G6 GTP
2012 Nissan Juke - (hers)
2000 SV650 - naked, integrated tail light, sliders, corbin, pilot roads, RK chain & sprokets, D&D full exhaust, FactoryPro Stage I jet kit, +4 Ignition Advancer, Barnett race clutch
2006 Triumph America 900 - Full Dresser

January 2009 Grand Cherokee of the Month (GCOTM)
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