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IM thinking about putting a set of shorty header on my 87 Chevy pickup. It now has stock manifolds with cross over pipe. The 02 sensor is on the drivers side manifold. I was going to weld an adapter above the collector on the same side. Add another converter and run dual instead of the crossover. Will this mess with my emissions at all. It's a late 87 model so it does have EFI and is not carbed.
I don't think it will harm the emissions by going that route as long as you install the cats preheater hose on the new cat to keep it stock-like. Assuming it has that feature now...
But if you're going to cut and weld on some shortys, why not buy the right set with an O2 fitting already added?
The reason IM even thinking of using these header is because they are hanging on my wall. The old manifolds are cracked. I just wanted to use what I have without buying anouter set, but wanted to make sure it would pass the smog test before spending money for nothing.
:confused: youer not getting much help here bowtie so ill give you my 2 cents worth. we dont use the sniffer here, but my thanking would be that the truck would run ok that away but i dont belive you would get the same sniffer reading on the pipe with the o2 sensor as the pipe without the o2. i think youer going to have to have a o2 sensor in each pipe, but i dont think you can do that with the computor you have. i belive you could get around it with a cross over pipe at the collectors. could be wrong. :rolleyes:
Install considerations for your 02 sensor should be heat of sample gas. You will have great results if you keep it close as possible to heads like it is now. You mentioned welding above the collector and on the shorty that is pretty close to the head flange.
Mounting 1 sensor in the collector where 4 pipes merge into common pipe will give you an average sample of that bank of cyl's and the EGT will still be high. On a single sensor install you have choosen great location. If you mounted downstream or in the crossover pipe between new dual system it would seem to be in a better place from an average of sampling but would give very different reading because of extreme heat difference.
In a system with multiple sensors ( in E manifold = before the Cat = after the Cat) Design accepts lower temps but now compares to each other for funtion. Said different if now a system in manifold try to keep in close to same range. If changing to multiple sensor ECM then lower temps are OK and duplicate their locations as close as possible. BEEN THERE and found this out the hard way!! Without changes to system I read .82 in collector at end near muffler, and .71 some 10 inches closer to eng. and .64 in #8 tube at merge to collector on this Toy