Suggestions for upgrades

[patlisa514]

I have a 99 stock Sahara 4.0 Automatic and was looking for suggestions to improve performance, what kind of ignition or muffler system, or whatever may come to mind. Not looking for cosmetics at this time but performance and gas mileage. Thanks for any feedback. patlisa514 I am looking for around town performance and some off road

 

[redrooster]

It really depends on what you see yourself doing with the Jeep. I think the engine department is suitable in stock form, but there are plenty of bolt on mods. I would suggest starting with a JET computer chip.
If you intend to take it off roading, the greatest performance mod would be stuffing the axles with lockers. If you don't know what those are or what kind you want then just search back through the forum. There are multiple discussions on the subject.

 

[Craig]

I'd say one of the easiest and cheapest mods to do is a K&N filter. A free mod (if your's has it) is to remove the air restrictor in the hose of the air intake between the filter and intake manifold.

 

[TwistedCU]

Engine mounts

Well if you do all the advertised mods that boast 5-10 hp, you'll end up with a 300 hp 4.0L!!! :lol:

Removing the airflow restrictor and putting in a K&N drop-in air filter was my first thought also. That, a set of dual tipped spark plugs, and an electric fan conversion definately gave me considerably more pep on my 2.5L.

 

[Snitty]

replacement K&N air filter, remove restrictor, not sure if TB spacers work, but possibly an improvement, high-flow cat, or hollow cat with O2 simulator, not sure if a chip really helps but possible, high flow cat back, electric coolin fan, better ignition wires

 

[jps4jeep]

Maybe a LS8 454 out of a chevelle would give you jeep a bit more power!! hehe!!

Forget the cat idea, you live in mass and we can't mess with egr stuff!
The simplest equation for more power is, increase spark+increase air+ increase fuel+ increase exhaust=more power.

Exhaust and intake work will yeild a nice performance increase! later down the road you can add wires and plugs to increase spark then at the same time a chip or bigger injector to increase fuel.

 

[redrooster]

Throttle body spacers do work. The reason I mentioned the JET chip is because the author mentioned fuel mileage. The Jet chip is supposed to up horesepower and improve mileage. THey are about $250 but if they save fuel, you'll make that back pretty quick.
Basically the factory tunes the motor down for longevity. The chip changes your timing curve and increases power. It is also easliy removed to return it to factory settings. Read up on them.

 

[jeepdude832]

I dont know if my jet is broken but I notice absolutely no difference wether its plugged in or not

 

[Snitty]

bigger injectors really won't really do you much good unless you get into the engine... simply supplying more air in/out by intake/exhaust will not be enough to allow the injectors to work... changing the cam may be enough to take advantage of injectors

 

[jps4jeep]

I have been told by a mopar mechanic that the injectors off the rt dakota will fit the manifold of a 4.0 but have a higher flowrate. I forget by how much the increase is, but it was not monumental. But this is similar idea to re-jetting and setting floats in a 4bbl carb, right?

If you increase the amount of air and exhaust, the motor has a tendency to run on the slightly lean side, A motor makes the best power over the its RPM band when the air/fuel is as close to stociometric (help with spelling) as possible. Hence by increasing the amount of air and fuel in the cumbustion chaimber, greater "explosion" equals more power.

 

[noskils32]

A suspension lift and bigger tires will give you a noticeable difference!!

 

[fourtrail]

Install a free flow cat back exhaust and a K&N filter and remove any restrictions between the air cleaner and throttle body. Also a tbi spacer may help, but only on the upper rpm range and they cause an annoying whistle I know from experience. Also look at a 50-state legal header. On the ignition side I suggest a Jacobs ignition. They only help increase spark and don't change timing so you can still run the cheap gas. They trigger off of the stock coil so they are easy to install and most come with a new set of plug wires. Hope this helps.

 

[patlisa514]

Just wanted to thank everyone for their input, I appreciate it. Fourtrail, I will check into the ignition, I have 92000 mi so a complete tuneup is due I am sure. thanks Patlisa