View Full Version : best upgrades to exhaust? for TBI injection
02-05-2006, 11:02 PM
I have been looking into getting a new exhaust in the rig and I cannot seem to find the answers that I want when it comes to fuel injection. I am assembling the peices to put together a throttle body system and I wanted to run dual exhaust. The only problem is the exhaust shop doesnt mind putting in the duals but they leave it to the customer for the placement of the oxygen sensor. I guess it would go in the H pipe (center?)? From the research I have been doing on the net I cannot seem to find anything about placement of an oxygen sensor with dual exhaust on a tbi system. Al I keep encountering is laws on how its not legal and why it should not be done etc.
Are any of you running duals on a tbi setup? If so where did you place the oxygen sensor which seems to be critical to system performance. (I still have to pass the sniffer test so misplacement of the sensor will kill that.)
I guess my next best option is to keep a single exhaust but upgrade to 3" pipes?? If so what cat works well wich such a system?
any help in opening up the exhaust will be much appreciated.
02-05-2006, 11:04 PM
I forgot to note that I have come across some articles on Vettes and other dual exhaust rides noting how there are two oxygen senors. One on each side of the ehaust. If using such a system I would probably have to find a computer with input for two sensors as the standard ECM out of the Che*y trucks that I intend to use seems to inly have input for one.
02-06-2006, 12:28 AM
Placing the O2 sensor fairly close to one manifold or the other helps it warm-up faster, thus reducing emissions after start-up by getting the system into closed-loop operation more quickly. I put it in the drivers-side down-pipe, maybe 8" aft of the manifold. Sensing just one bank is not a problem unless some cylinders are running rich or lean, or mis-firing, in which case you have larger issues that'll befuddle the sensor anyway.
On mine (a fairly hot, high-revving 360), I did a custom 2-1/4" to 3" y-pipe, cheap 3" CatCo cat, a huge, quiet 3" junkyard muffler, and 3" pipe out to the stock location. If you absolutely must have duals for cosmetic reasons, you're better off with a single 3" in, dual 2-1/4" out muffler.
02-06-2006, 01:54 AM
The best place is right after the junction in the Y-pipe, but as said above, you can place one closer to the manifold (GM used this method, sometimes right in the manifold itself on TBI rigs), and the sensor will warm up faster. The only downside of this, is it's only monitoring one bank of cylinders.
02-06-2006, 04:19 AM
I am planning on installing a heated sensor so I dont have to worry as much about the sensor heatin up. From what the two of you are saying it seems right after the junction in the Y pipe will be best and it will give me the best readings. I think that I will keep the stock y pipe and upgrade the cat and muffler and exhaust from the y pipe back.
02-06-2006, 05:32 AM
With a standard GM tbi setup you need to put the 02 senser as close to the exhaust manifold as possible so that it reads the exhaust correctly. ( I use a single wire non-heated sensor). The remainder of the system should not matter if you run duals or single exhaust.
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