Exhaust Modifications

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Homeward_Bound

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KJ Supporting Member
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After some recent wheeling adventures, the idea of solid swapping the front end has come back to the drawing board for me. Yes it would be easier to pick up an older XJ or TJ, but where is the fun in that? For now it is still all theory. However, if I can have it all figured out beforehand, it will be a smoother transition.

I'm confident I have the computer issue solved for the ABS/ESP. JK and KK wheel sensors are a passive, 2 wire system. Theory is that since it is passive, the ABS is not looking for a specific tooth count. Rather it is looking for an equal tooth per revolution from each time ring to determine slip and whatnot.

For comparison, the JK/JL tone ring is 52, while the KK/WK/XK tone ring is 48 tooth.

Fabrication is only as hard as the imagination makes it out to be. And another area I am confident I have accounted for.

But one issue I currently am having trouble with is the emissions control. On the KK, the driver side catalytic converter sits right below the front drive shaft. And living in NY, I have to have a California Emissions Compliant catalytic converter to keep it street legal. But the drivers side catalytic converter will need to be relocated for front driveshaft articulation. To allow this movement, I have come up with three options.

First option is to cut and move the driver catalytic converter to underneath the bell housing. Trying to tuck it as high as practical in that space. This was done on the solid axle KK in California and his still passes their emissions test. This is most likely the route I will be taking. But for conversations sake, I added a second and third option.

Second would be to use a setup from a JK 3.8 since the catalytic converters are already tucked up into the engine bay. But this has its own issues since the JK 3.8 has 4! catalytic converters, 2 smaller ones per side. And the O2 sensors are in different places as compared to the KK. Would this approach even be practical? My gut feeling says no.

In comparison, both the JK and KK have 2 banks of O2 sensors, 2 sensors per bank for a total of 4.

For the KK, bank 1 is before the catalytic converter while bank 2 is in the middle of the catalytic converter.

For the JK 3.8, there are 2 catalytic converters per exhaust manifold. Bank 1 is in the inlet to the first catalytic converter which is directly after the exhaust manifold while bank 2 is in between the two.

What I'm getting at here is asking if the location of O2 sensors greatly affect the emissions.

Option 3 is to go full custom exhaust to get everything in the right place. However I belive that this would be the most expensive option.
 

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