88cherokee

What is the best proformance upgrades to do on the 4.0 motor to get more torque?

muddeprived

replace it with a rare 350.

There are a number of upgrades that give you a little bit of gain but none of them give you OMFG!!!! gains. Maybe a supercharger would but those are worth more than most xj's out there.

I would say the combination of taking more air and spitting it out. Bigger exhaust, bigger intake. Best start right there.

BlueXJ

Keep in mind when doing any performance upgrade on any motor. More air in and more air out. It is just a complicated air pump.
What ever accomplishes the above is the solution to getting more performance from any motor from a lawnmower to a F-16 Jet.

paroxysym

junk the 4.0 and throw a 4bt diesel in it.. seriously the 4.0 has plenty of torque, you can do little things like exhaust, maybe an intake, gears for more torque and some hp. but the 4.0 in these jeeps is built to put out as much as it can in stock form. you change the cam, lifters, internals yea you will put some bigger numbers out. but a stock 4.0, you will be squeezing small gains out of it.

BowtieGuy3

Go to Comp Cams, and check out their selection of cams for the 4.0L. Careful though, if you go with the highest grind, you'll probably have to regear or add a vacuum reserve canister, maybe both to be on the safe side. And don't forget... ALWAYS CHANGE YOUR LIFTERS WITH A CAM SWAP!!!
Get new pushrods too. After that, you can always get new rocker arms if you want.

Hesco is reportedly working on an aluminum head for ALL 4.0L's and an upgrade for the 4.2L's. Don't know when its coming out though.
^ Scratch reportedly, it right on their main page now!

Check with your local go-fast shop, a lot of those guys will be able to help you w/ advice And think it's pretty cool ordering stuff for an oddball engine. Hell some might even install it for you, I have one here that will.

Here's some links to help you get started:
http://www.hescosc.com
http://www.summitracing.com
http://www.winnerscircle.com
http://www.compcams.com
http://www.whitespitstop.com
http://www.cranecams.com
http://www.lunaticams.com
http://www.cranecams.com
http://www.ersoncams.com

That should keep you busy for a lil while. I LOVE go-fast parts!!! (If you couldn't tell! )

nick_n_ii

With looking for performance upgrades, check out this posting..
https://www.cherokeeforum.com/showthread.php?t=6347

It's about alot of the upgrades you can do to the 4.0L and what they help...

BowtieGuy3

Hey Nick, on that perf. thread, that ported HO head, is that using SBC 2.02's/1.60's?

nick_n_ii

I'm not sure, see found that years ago but have yet to read it through and through..

JakeWI

i wouldnt go with a supercharger on these for sure. They cost way to much. at that point you might as well take that 4.0 and stroke it if you really want some gain out of it.

nick_n_ii

We also have a write up for stroking it also..

https://www.cherokeeforum.com/showthread.php?t=6404

93XJLI

a true bored TB (not a backyard mod) will give you the biggest seat-of-the-pants increase for the cheapest and easiest.

98 JeepJeep

I have been eager to get one...there is a guy who does them for 90$ strokerjeeps or something like that. i think with a CAI it would be a awesome upgrade.

BowtieGuy3

is there a sticky on that one?

nick_n_ii

Yes it's in the Tech write up area, seeing as it works for many Jeeps...

BowtieGuy3

Ya kinda missed that inference there Nick....