What's the difference?

[HPI_Savage25]

So I have a 1990 XJ with the 4.0 and I have been looking through the Quadratec catalog at headers and I can't find any for a 1990, everything is for a 1991+ ?

Thanks

[OhJeepers]

I may be wrong BUT, my 1990 is a Renix motor an I can't find upgrades for it either because the Renix motor was an epic fail :p. But I took a lot of parts of a 93 h/o motor an put them on mine, things such as the intake manifold, throttle bottle so I could get a throttle body spacer, an took my clutch fan off an put dual electrics that were supposed to go onto a 91 h/o. A lot of parts off the 91+ will fit onto the 90 some... may need minor modification thou. Again I may be wrong, but there is how I solved my dilemma

[OhJeepers]

I almost forgot I took the Renix cooling system out because again it was junk an swapped it with a h/o one from a 95 TJ

[bluedragon436]

I know one of the main reasons they don't sell headers for the 90 is because it still has the EGR tube that runs from the exhaust manifold to the intake.. I only know this because we were looking for a header when we swapped the engine out on one of our new member's 90 XJ, and the exhaust manifold literally fell apart in my hands when I took it off the engine.. I would love to have bypassed that EGR crap and stuck with the full 91 setup.. but couldn't find enough info to do that "conversion"..

[4.3LXJ]

That would only be an issue for emissions control. Eliminating that feature will give you more hp, but increase your NOx emissions.

[HPI_Savage25]

Well down here in GA we dont have any type of emission testing or anything so could I put a set of headers on it for sale a 91+ Cherokee?

[4.3LXJ]

Why not, and change the head to an HO head while you are at it and gain some hp

[HPI_Savage25]

I may end up doing all of this to the 89 motor I have in the parts XJ. I can then take my time and rebuild it, while throwing in some goodies while in the process. I guess a HO head, headers, maybe bore it out some, and not sure what else yet...all possibilities

[4.3LXJ]

I may end up doing all of this to the 89 motor I have in the parts XJ. I can then take my time and rebuild it, while throwing in some goodies while in the process. I guess a HO head, headers, maybe bore it out some, and not sure what else yet...all possibilities

Might as ell throw on a 99-01 intake while your at it then.

[bluedragon436]

^^ +1!! If you are going to do the headers and a HO head, might as well hook up a 99+ IM, some better flowing injectors, and a bored TB.. or at least do your own bore job, and get rid of that slight taper on the bottom of the TB if not a full bored job!!

[dagr8tim]

^^ +1!! If you are going to do the headers and a HO head, might as well hook up a 99+ IM, some better flowing injectors, and a bored TB.. or at least do your own bore job, and get rid of that slight taper on the bottom of the TB if not a full bored job!!

Even if you don't go a header. Get a like 97 or 98 exhaust manifold. In 99 Jeep made the exhaust manifold more restrictive, and that's why it got a more open intake to keep the power up.

Some people say the 95 head flows the best also.

[RustyXJ]

Don't know if they still offer it, but several years ago I replaced the stock cracked exhaust manifold with a ceramic coated Pacesetter header with a CARB #. Been very happy with it.