new vx exhaust manifold?

[hamsterpower]

Originally Posted by cbaber

Its illegal to even move the cat in CA? Thats a bit too much regulation. I am so glad I live in MO. There are no such things as emissions tests here. Sometimes they dont even look under the car to check for a cat!

Yes it is illegal, but it is a federal regulation so it applies in MO too.

[greasemonkee]

I missed this thread by a few days -

I used the DX 92-95 manifold on my VX, it seemed to me like it would be greatly more efficient, with stock reliability - this did require using the cat-in-tunnel type setup the DX/LX used and welding another bung in the top of the lower pipe.

I think I have the top section, and maybe the lower section of the CX/VX manifold, no usable cat though.

[ian]

Originally Posted by greasemonkee

I missed this thread by a few days -

I used the DX 92-95 manifold on my VX, it seemed to me like it would be greatly more efficient, with stock reliability - this did require using the cat-in-tunnel type setup the DX/LX used and welding another bung in the top of the lower pipe.

I think I have the top section, and maybe the lower section of the CX/VX manifold, no usable cat though.

Did you use the stock DX cat with this setup or did you go with an aftermarket one? The last owner of my VX put a DC header on it w/no cat and right now I'm trying to decide whether to put everything back stock, or to just put a cat inline with whats already there.

I was also wondering if I would have to add any additional heat shielding to the exhaust tunnel around the cat. What was your experience with this?

Making it even more complicated for me, I'm in California. I don't know if moving the cat that far downstream will give me emissions problems. I had read that Honda moved the cat right up to the manifold so that it would burn a little hotter to fix an emissions problem (I think it was high nox) during lean burn. If you have any smog test results on your setup, I'd love to see them.

Thanks,
Ian

[greasemonkee]

I have no idea how CA does its emissions. If a stock civic LX can pass emissions with it down stream I doub't it would have a problem. To my knowledge the catalyst is that far up in order to light off sooner. Once lit, I doubt the EGT's affect the temp of the catalyst.

The D15B7 engines had the fast idle thermo valve to crank the cold idle up some more right after startup. You don't see those on engines with the cat in the manifold.

If CA allows it I'd hang on to that DC header, you might pick up 1mpg.