Dual exhaust issues

[foxtrot]

I would like to install a custom dual exhaust onto my 1986 regal (GN clone).

I have obtained a pair of Thornton Dual Exhaust Manifolds: http://www.tntmusclecars.com/350jr_exha ... folds.html. I'm planning on running two 2.25" pipes thru a dual input/output cat on the passenger side and finally thru two high flow mufflers.

This issue that comes to mind is the o2 sensor. It currently is installed after the y connection and with the new exhaust I was planning to install the o2 sensor in the dual cat. Will the temp from the dual cat burn out the o2 sensor?

Thanks for any advice.

 

[dan2286]

Are you talking about putting it in the actual cat. housing?

 

[megaladon6]

if i'm reading this right you're running 2 pipes to a single cat and 2 pipes out of the cat, correct? is the internal design of the cat an open system where the gasses from both pipes mix or is it a split system?
are you running the stock 80's narrowband O2 sensor and computer controlled carb or something else?

 

[foxtrot]

.

 

[foxtrot]

Yes -- I'm thinking of installing it in the cat housing. The last time (~16 years ago) that I did a similar project -- the 02 sensor was installed at a crossover point...

 

[foxtrot]

The cat will allow the gasses from both pipes to mix...

 

[megaladon6]

the best way to do it would be to connect the pipes just before the cat and put the O2 sensor there. however, given the simplicity of the system and the narrow band sensor you should be fine with just putting the sensor in one pipe, pre-cat.

 

[foxtrot]

Thanks for the info -- one would think that If the o2 sensor was on in one of the two exhaust streams that the comptuter would think that the exhaust was lean by %50...

I haven't done any real research here...

 

[megaladon6]

the best way is to read all the gasses but since you've upgraded the engine and since the CCC system is so basic you can get away with it. like i said, if it was (modern) EFI it wouldn't really work.

 

[olds307 and 403]

I for one thought Sanderson headers would out perform the Thorton maifolds for similar money. The Sandersons fit nice and tight, I fabbed my dual 2.5" pipes thru the passenger side with a compact x pipe. The Thortons should still out perform the lousy stock manifolds.