what is the better header for a 2.5

[cz777]

i am looking for the better header for the 2.5 liter with m/t ,2 wheel drive set up ? anybody played with them of different makes,tested them for life/power out put yet?

[shelbyluvv]

The 2.5 does not respond well to mods. It is a tiny 4 popper and there is not much you can do to get a performance boost. Do not waste your money on hopping up a 2.5 in a MJ.

[AMCJeepMJ]

I've seen 2.5 Mopar performance cams, but as stated above the payoff is not worth the expenditure.

[Suuperman]

If you NEED a manifold...then is a good time to get a header.

 

As stated above you won't get much from it.

 

I have used a pacesetter header on 2 of my 4 bgnrs in the past with good luck.

 

My friend has on in his 4 bngr YJ and it has been in there for the better part of a decade and he's had no trouble with it.

 

They are only a little bit more $$ than a stock manifold (I remember paying under $200 each for mine).

 

I have used banks on one of my 4.0L with good luck but I think even the banks 4 bngr headers are pricey if memory serves.

 

If you do this, get a good muffler (do NOT delete the cat on a 4 bngr), a 4.0L TB and 4.0L TB spacer you might see 10 HP...maybe. One of the better upgrades is to switch to an electric fan if you have not yet done so. I've run a 16" parts store fan on every jeep 4 bngr I have owned and they respond well to it and stay cool easily. Also even with a 2wd...regear it. Run 4.56's with stock sized tires...that's where you will really see a difference.

[cz777]

i have a understanding how things work with 2.5 .but if you get better volumetric flow both intake/exhaust better hp/mpg both count here ....so stock exhaust manifold is good but know to crack i have heard is this true? ''catch a trouble spot before hell is to paid'' thxs

[dasbulliwagen]

The 4.0 throttle body mod will only work if you have a 91 or newer port injected 2.5, and removing the cat won't make a difference in the 2.5 powerband. I have a gutted and sleeved cat, flowmaster muffler, removed engine fan and added electric fan, and a high flow air intake tube and filter, and have noticed small power gains with each of them. I have plans for a header in the future, and am hoping to get the Pacesetter. Id like to do a cam too, but finding one has been next to impossible. Mopar used to have one, but is no longer available, and theres a Canadian company outside of Vancouver that used to have a selection of them listed, but their website says they have been temporarily shut down for quite a while now. ......Just rechecked their site, its now back up, and they no longer list a cam for the AMC 2.5. :fs1: Might need to look at companies to do a custom grind.

 

And don't listen to all of the naysayers in regard to 2.5 power mods. If the 2.5 is all you have to work with, then by all means do what you want to. Yes its true that a 4.0 will give you everything you want and more, but if its not feasable to have one installed, then do what you have to do, with what you got. But if you do modify the 2.5, just don't get your hopes up too much.

 

Clifford has a 2.5 intake listed on their website, and Ive wondered about adding it and then modifying a 2bbl TBI injected throttle body from a GM v6 to it to work with the factory wiring and controls. I'm not sure though that the RENIX PCM would be able to have enough power output to control two injectors. The injector is controlled through on off times by the computer through inputs from the 02 sensor, and Throttle position sensor. I would think that if the computer could control both injectors, it would just cut back the on time to compensate for the additional fuel from the second injector to keep air fuel raio where it needs to be. That is assuming that all the sensor parameters between the two styles of throttle bodies are the same or similar. Ive yet to try this, but have been tossing it around in the back of my mind for a while now, and an initial look at the service info finds at least that the TPS voltages seem to be the same.

 

Anyways.... good luck with whatever you come up with....let us know how it works out.