allroad enthusiast test: When you see this pic what do you think?
01-29-2006, 11:49 AM
#13
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Thread Starter
Well, that was the 2nd thing that crossed my mind, but I'm not doing it that way.
I'll be doing motor mounts and a clutch and who knows what else so it won't make any sense for me to kill myself to try to sneak 'em in.
01-29-2006, 01:19 PM
#14
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I heard the term "pigify" before but....
didn't know exactly what was meant by it, please explain and expand. Also, why would you have to relocate o2?
I'm going to have to try and remember raxles.com for the future. Any ideas on cost? Also feedback of these guys would be appreicated.
I'm going to have to try and remember raxles.com for the future. Any ideas on cost? Also feedback of these guys would be appreicated.
01-29-2006, 04:11 PM
#16
AudiWorld Super User
Thread Starter
Making Piggie Pipes is nothing new in the tuning world, but somehow a guy named Piggie in S4 land
started making them for other S4 owners and they took the name Piggie Pipes. Basically the downpipes on the 2.7T have pre-cats directly aft of the turbos. The purpose is to have a catalytic converter where it will heat up much quicker thus reducing cold start emmissions.
The main catalytic converters are under the car where you would expect them. The idea with Piggie Pipes is to tear the guts out of the pre-cat on the stock downpipe effectively making it a high flow downpipe nearly equal to a very expensive aftermarket downpipe.
The ECU monitors 4 O2 sensors on the car. One each before the pre-cat on each side and one each before the main cat on each side. The car sees that the pre-cat is doing its job by comparing 02 readings before and after and usually all is well. When I gut the pre-cat the downstream 02 sensor will know that the exhaust is not being 'cleaned up' as it should and throw a nice CEL.
The solution is to move the 2nd 02 sensor on each side to a new bung behind the main catalytic converter. The hole ahead of the main cat is welded closed.
So for minimal money you get 95% of the benefit of big money downpipes. They will work fine on a stage 3 car making big powAh.
The car will still have normal cats and will not be a polluter. The only change will be slightly dirtier cold starts. It will not through a CEL and will pass any emmissions test.
The main catalytic converters are under the car where you would expect them. The idea with Piggie Pipes is to tear the guts out of the pre-cat on the stock downpipe effectively making it a high flow downpipe nearly equal to a very expensive aftermarket downpipe.
The ECU monitors 4 O2 sensors on the car. One each before the pre-cat on each side and one each before the main cat on each side. The car sees that the pre-cat is doing its job by comparing 02 readings before and after and usually all is well. When I gut the pre-cat the downstream 02 sensor will know that the exhaust is not being 'cleaned up' as it should and throw a nice CEL.
The solution is to move the 2nd 02 sensor on each side to a new bung behind the main catalytic converter. The hole ahead of the main cat is welded closed.
So for minimal money you get 95% of the benefit of big money downpipes. They will work fine on a stage 3 car making big powAh.
The car will still have normal cats and will not be a polluter. The only change will be slightly dirtier cold starts. It will not through a CEL and will pass any emmissions test.
01-29-2006, 04:13 PM
#17
AudiWorld Super User
Thread Starter
Forgot to answer the 2nd question:
<ul><li><a href="https://forums.audiworld.com/allroad/msgs/141793.phtml">this is where you will be kahliking.</a></li></ul>
