Rebuild the 4l and improve it.
 

So I am looking in to the age old problem.
Do I upgrade or rebuild.
Upgrade to what. (XJ check all my box's for an off roader).
or
Rebuild a XJ and run it for another 10-15 years through retirement.
If you rebuild a 4L what to do to it to improve it.
I run 90% of the time around 2000rpm. I don't want any increase in power above 2000rpm or increased fuel consumption. Working up a bit more torque around 2000 if possible with out going to premium fuel.
Cheers

Interesting question

from my basic knowledge of engine building theory, there isnt a lot you can do to increase power at lower RPM, apart from (maybe) a different camshaft, but more importantly, an increase in stroke

To the limit of my theoretical knowledge, most improvements work across range or at upper end, some even at the expense of low-end response..ie increase flow (alone) for more power will usually make idle & low-end response worse.

The white one I have with headers and big exhaust seems to have more power, but once again, in theory, this would be mainly (or all) at above 2000rpm

how many kms does your unit have on it?

Depends on what you want to spend, a small supercharger would give you everything you want.

Research RV or tow cams for the jeep 4.0.
then decide if you want to go the stroker option if you rebuild.

Good question. just remember its increased torque you want at the bottom end. Probably some sort of retune of the fuel injection & cam changes. Dont ask for more power as that normally only occurs at the top end.

obd2 PCM's can be retuned OBD1 not so much looking at piggy back controllers for that.

probably need a little more info r/e the condition km done compression figures.

my personal take is, and this is very much dependant on what you want to do.

in my case and I'm retired and have no intention to part with my jeep

i have had great results using the later horse shoe inlet manifold and extractors plus 2.5 inch exhaust. next is removing the mechanical fan and going to either two or three electric fans ,removes the horrendous roaring noise plus frees up a small amount of HP, plus the thing just sounds sweeter.

and if you are running larger dia tyres then going to 4.10 gears is a huge improvement.

i generally get 500 km out of a tank of mixed city highway use, stop start makes it really bad really quick.

at 435000 km i have 125 to 135 comp readings, and while it does feel a little tired its only noticeable if i want to be a boy racer ( which I'm not, well ok occasionally hehe)

this is purely my opinion and other may have better advise

macca