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Mopar Computer/performance mods


 
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nixt
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Joined: 17 Aug 2005
Location: Atlanta/Athens, Georgia

PostPosted: Tue Sep 12, 2006 4:42 pm    Post subject: Mopar Computer/performance mods Reply with quote

I've gotten some money burning a whole in my pocket and I'm looking to spend it on my '98 ZJ 5.9 Limited. I've been looking at the Mopar Performance Engine Controller (PN 4876898). Is this thing really worth $370? I can't seem to find any specs on what kind of performance gain you get when you install the new computer. Aside from the cost, the main drawback I see is having to use 92 octane fuel, but the 5.9 already requires 91 octane fuel. In North Georgia, premium unleaded is 93 octane and mid-grade is 89 octane. So now I can save a little money by mixing premium and mid-grade gas 50/50 to achieve a 91 octane mix. Is there any other engine mod that I can do to improve performance for around $400? I've already gotten an aftermarket air filter kit and exhaust installed. I'm not looking to hurt my engines reliability or do any bottom end motor work. Another option I was looking at was an underdrive pulley to free up some horsepower but I'm not sure as to what brand to get, how difficult it will be to install, or what type of performance gain I would get. Does anyone have experience with performance computers or underdrive engine pulleys?
-nixt
_________________
1998 ZJ 5.9 Limited W/242 swap
JKS disconnects & Garmin GPS
Heavy duty OME Suspension kit
with 2" coil spacers for 3.5-3.75 total lift
235/85R16 Goodyear MTR's Measure a true 32"

Life has No Value,
But Death Has Its Price.
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1fox2go
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Joined: 01 Dec 2004
Location: Fishersville, Virginia

PostPosted: Tue Sep 12, 2006 6:09 pm    Post subject: Reply with quote

SUPER CHARGER rofl , try the hypertec and superchips websites maybe they have a chip that would work for the 5.9

is it still quadratrac? if so id swap the 231 tcase so you can smoke the tires at stop lites and stuff Mr. Green
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96 Cherokee 7.5 inch TnT long arm Locked F/R, D44 rear, 4.56s, 35x12.50 Muds/36x12.50 TSLs
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nixt
Member


Joined: 17 Aug 2005
Location: Atlanta/Athens, Georgia

PostPosted: Tue Sep 12, 2006 7:37 pm    Post subject: Reply with quote

I just searched the superchips and hypertech websites. When you do the "search by vehicle" search on the superchips website it only lists the 4.7 motor for the Grand Cherokee and the earliest year that is listed is 1999. I don't know if they don't make chips for ZJ's anymore or if they ever did- but I can't find anything for any ZJ on their website. The Hypertech website only has the 4.0 for the 1998 ZJ- So I guess that I'm in the same situation with hypertech as I am with Superchips.
As for the transfer case, I did the swap from the 249 to the 242. I'm happy with the 242 right now so I'm not going to do anything with it except maybe get the speedo gear corrected for my 235/85R16 (32") tires. I've started thinking maybe about a larger throttle body and spacer kit- but again I can't find any info about what types of performance gains I may get.
Using Larry Shepard's How To Modify Your Mopar Magnum V8 as a reference, he lists the cat-back exhaust and cold air intake as the level 1 performance package, and low-ratio underdrive pulleys as level 2. For level 3, he lists a high performance computer but with the explanation that a high performance computer could have been the first, or level 1 step. He explains that a high performance computer is basically required for any future performance gains to deal with the increased demands on the oxygen/fuel ratio. He doesn't mention anything about a larger throttle body or spacer in the 9 levels of performance laid out in his book- he just says that after a larger aftermarket cold air intake is added the throttlebody is the bottleneck in the top end of the motor.
I've found some sites that offer underdrive pulleys:

https://www.rpmoutlet.com/aspmopar.htm
http://www.streetbeatcustoms.com/asp504522.html
http://www.streetbeatcustoms.com/asp504500.html

But still, none of these sites say how much power is gained. However, the pulleys are way cheaper than the Mopar performance computer. I guess my questions are: Does anyone know how much power is gained with either the Mopar Performance computer or underdrive pulleys and which one should I go with? Since the computer or pulley can be alternated in sequence of performance building I just want some advice on what is the best option.
-nixt
_________________
1998 ZJ 5.9 Limited W/242 swap
JKS disconnects & Garmin GPS
Heavy duty OME Suspension kit
with 2" coil spacers for 3.5-3.75 total lift
235/85R16 Goodyear MTR's Measure a true 32"

Life has No Value,
But Death Has Its Price.
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nixt
Member


Joined: 17 Aug 2005
Location: Atlanta/Athens, Georgia

PostPosted: Tue Sep 12, 2006 8:01 pm    Post subject: Reply with quote

I just read a thread on the TJ section of the forum about throttle body spacers-
http://www.jeephorizons.com/phpbb/viewtopic.php?t=8804&highlight=pulley
The argument against spacers is pretty convincing and recommends an electric fan as a much more efficient and reasonable option as a way to gain a few extra horses. The 5.9 came with an electric fan from the factory so I've definitely narrowed my performance options to the underdrive pulley or computer. According to the guys at Summit Racing, the Mopar performance computer gives gains of 10 horsepower and 12 to 15 pound-feet of torque. That sure as hell doesn't seem like much for almost $400. So now I'm definitely leaning toward the pulley setup- but I'd still like to hear from anyone that has experience with an underdrive pulley swap. Does it alter the driveability or reliability of the vehicle? Or does it affect the fuel economy or the operation of any of the engine driven accessories?
-nixt
_________________
1998 ZJ 5.9 Limited W/242 swap
JKS disconnects & Garmin GPS
Heavy duty OME Suspension kit
with 2" coil spacers for 3.5-3.75 total lift
235/85R16 Goodyear MTR's Measure a true 32"

Life has No Value,
But Death Has Its Price.
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1fox2go
Member


Joined: 01 Dec 2004
Location: Fishersville, Virginia

PostPosted: Tue Sep 12, 2006 8:16 pm    Post subject: Reply with quote

well the way im lookin at it right now...you have about 400 to play with, you could save up and build you a hell of a 5.9

not sure about the price but a friend bought a book on how to build ford small blocks on the budget, he read somewhere that you can build a 302 puttin out about 400 hp for about 2000, if thats accurate or not im not sure, but i am sure there is a book on building mopar small blocks tho
_________________
96 Cherokee 7.5 inch TnT long arm Locked F/R, D44 rear, 4.56s, 35x12.50 Muds/36x12.50 TSLs
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nixt
Member


Joined: 17 Aug 2005
Location: Atlanta/Athens, Georgia

PostPosted: Tue Sep 12, 2006 8:49 pm    Post subject: Reply with quote

I just searched over on jeepsunlimited.com for any numbers they had on underdrive pulleys. The numbers are about the same as for the performance computer (roughly 10 hp). Apparently, when you get the underdrive setup you can't use the stock belt anymore and you have to do some searching to find one that fits. One person commented that with the underdrive setup you may run into some problems with the accessories and draining if you do a lot of idling (city driving or being stopped at a drive thru). He stated that you solve this by applying the throttle which would lead me to believe that the fuel consumption would definitely go up. The mopar computer would seem to me to be more reliable and not make the driveability suffer adversly. But the computer setup would cost twice as much as the pulley and cost a little bit more at the pump. My ZJ is my only vehicle and therefore my daily driver and I just cracked 100K miles. So I don't need to make a speed demon- I just want a little more horsepower. As for the book- I've purchased both of Larry Shepard's HPBooks; How To Rebuild Your Mopar Magnum V8 and How To Modify Your Mopar Magnum V8. They are both really good books and really informative. Since I lifted my Jeep and put the 32" inchers on it, it doesn't accelerate as well as it did before (that was expected). It will still chirp the tires at the stoplights but I thought about swapping the 3.73 to 4.10 gears but again that would make my fuel costs go up. After I wear out my current tires I'm going to step down to 31's. Of all the vehicles I've owned this is by far my favorite and I doubt I'll ever get rid of it. After I graduate and get into a real career I'll by another car and then get a rebuild done on my engine- but I can probably hold out until I have between 160-180K miles on it. Until then I want to keep it at a balance of power, reliability, economy, and still be able to take it on the trails.
_________________
1998 ZJ 5.9 Limited W/242 swap
JKS disconnects & Garmin GPS
Heavy duty OME Suspension kit
with 2" coil spacers for 3.5-3.75 total lift
235/85R16 Goodyear MTR's Measure a true 32"

Life has No Value,
But Death Has Its Price.
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jeepjeepjeep
Member


Joined: 28 Nov 2005
Location: elizabethtown.ky

PostPosted: Fri Sep 22, 2006 1:32 pm    Post subject: computer Reply with quote

http://www.trademotion.com/partlocator/index.cfm?action=MorePartInfo&PartID=198779&siteid=214012&catalogid=3326

prices are cheap computer is 259 other stuff on there two
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1993 jeep grand cheerokee
1994 jeep grand cheerokee wrecked
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