My 1999 xj sport is approaching its 200k mile mark andive begun the process of attempting to maximize the horsepower and efficiency of my engine. So far this is what I've done...
- replaced head gasket (it was blown)
- shaved the head (just enough to true it up)
- K&N air intake
- gibson headers

-spark plugs and wires
- I have also done a complete cooling system replacement including the heater core (which I don't care to ever do again)

Where do I go next? ..I'm not really interested in making any changes to the rest of the drive train, just the engine.

 

not much you can really do to free it up...
Have you changed injectors to 703's? 4 hole injectors

Also the only way ive been able to free it up is taken out the a/c system and also the mechanical fan clutch.. I have noticed a great difference in response and engine stress.. But really theres not much we can do to gain much extra power/torque.

 

63mm throttle body would help

 

Turbo

 

More air needs more fuel...
Our engine is going to take in the same amount of air with a 63mm or our so called restricted 59's.. may help more on highway than anything else..

 

Cold air intake ?

What diameter headers & what setup are they ?

I`m putting a 2.5 exuast system on my 96 from the bottom of the stock header flange to the tail pipe but decided not to go with header upgrade for now as I`m not %100 it`s the right thing to do for driving style. as the diameter and flow of the exhaust sytem has a direct impact on proper valving that insures all the combustion chamber gases are removed before the next explosion and this is what makes all the difference, who has the most fresh air mixed with gas on the next combustion...

I would just stop where you are while U still have alll that cash, and enjoy the JEEP !!!

J just
E enough
E essential
P parts

 

it depends how much you want to spend, if you want a lot of hp you can change everything better cam, bigger valves, coil, roller rockers, ect

 

703 injectors....ditto! I had a good response from that and porting/polishing intake and head + dynomax headers (muffler and etc) adjust kickdown linkage....clean clean clean!

 

id love to see pictures of your ported intake


id also like to point out that simply porting a head doesnt mean more power (not talking about yours) alot goes into properly porting a head, including flow bench time. an improper port job can actually hinder performance by disturbing the flow.

 

and to add to the thread....


this worked for me on a couple of my jeeps.

 

LOL what size shot you running sir? Wet or dry may I ask.

 

go baby go

 

Sorry to bud in on your thread But this guy seems to have some knowledge. I completely forgot about this, I`ve heard porting is the 1st upgrade that you should do to your engine before anything else. to late for me I already bought my exhuast up grade, N20Jeep could you throw in your 2 cents on this with some detail ? Would enlarging the valve`s been entirely nessesary or would the porting itself improve performance enough to be worth the time ?

 

For those of you new to this, the pictures below show the head intake & Exhuast valve chamber before and after it`s been ported. The other is what your Manifold exhuast may look like and what it looks like after having it polished.

I`m sure you can understand how that ruff surface would restrict the air flow.

I borrowed these pic`s from here: http://www.jeepstrokers.com/forum/vi....php?f=8&t=317

 

Around how much would it cost for the the valve and port job at a shop? Just an estimate?

I'f I ever change the head gasket this is a MUST.