2.5- 4.0 Exhaust Manifold Question

[dasbulliwagen]

Ive been looking at headers lately, and for some reason the cheapest one I'm finding are for the 4.0... economies of scale I guess. But anyways, I was wondering if I could cut the end pipes off a 4.0 header and put it on my 2.5. I would of course have to weld up where the 1 and 6 pipes were cut off. Does anyone know if the bolt pattern for these two motors is the same in the middle? Looking at comparisons of the flanges for each finds the pattern is similar, but I'm wondering if they are exactly the same in that area to where I could make something like this work. Here is the 4.0 header that got me wondering about this. Let me know what you think. The price on this can't be beat and the few reviews Ive seen have been good.

 

http://www.ineedparts.com/apn-jeep-exhaust-manifold.html

[Oyaji]

I applaud your ingenuity, but to get any benefit you would need to get a 4-into-1 collector instead of trying to mod a 6-cylinder collector.

 

If you insist on a header, have you tried talking a local muffler shop or other fabricator into making you a custom one? If you do, make sure to shoot for the longest primary tubes you can get: even 36" long are tuned for something like 5,000 - 5,500 RPM (if my memory serves correctly, that is - if you are really interested I could calculate). Since you are starting with a 4-banger, there might be room for longer pipes (longer drops the RPM for which you would get greatest benefit).

[carnuck]

Check out the Wrangler stuff for 4 cyl headers.

[TheDirtyJeep401]

You can buy a header for a 2.5 on Summit Racing

[dasbulliwagen]

Ive looked at all the options for Wrangler 4 cyl headers, just being the cheap jeep person I am the prices are a little out there, especially when you can buy physically larger and more complex ones for other models much cheaper, such as that one for the 4.0. I understand you pay for R+D, and economies of scale come into consideration, but sometimes it just doesnt make sense. Just trying to broaden my nuimber of options for when I rebuild my spare motor.