I want to get a test pipe/ race pipe (what ever people call it) and after doing a bit of research some people are saying adding a 3" race pipe with a stock exhaust will cause back pressure and that will lead to problems. Is this true? My car is chipped if it matters, and i also spoke to ecs tuning customer service and they said the spacers are already welded on so there will be no check engine light with this pipe.
Audi B5 A4 Quattro 1.8T > Search > Race Pipe > ES#1844140 B5 1.8T Race/Cat Delete Pipe Kit - ATP-VVW-138

 

Im pretty sure removing the cat and adding a straight through pipe would reduce back pressure... I could be wrong. But if that were true people wouldnt buy them. A test pipe adds tq and turbo cars hate back pressure so I doubt it. All that evidence suggests that is b.s but like I said, I could be wrong. Do you already have a cat back? Do you plan on getting one? I wouldnt get just a test pipe (not for a reason just because). Edit: on second thought I dont think a 3 inch test pipe flange would bolt up to stock exhaust flange???? Could again be wrong.

 

Ecs said its a direct replacement. That's what I was thinking also idk how it would fit. But I don't have any after market exhaust. I will buy one in the future...maybe

 

I recently installed my 3" ECS tuning ATP test pipe on to my stock exhaust and I must say the car pulls harder and longer up until redline where it used to run out of breath at about 5500rmp. I am also chipped and I am completely happy with it. I also removed the pre filter and lower flapper in my stock airbox to decrease the restriction. It is all held in with a couple screws and is 100% reversible.

As for the spacers, I didn't try it with just the O2 sensor by itself but when I installed the secondary sensor with 2 spacers, with the second one directly attached to the O2 sensor drilled out and the first one not drilled out, it gave me a reading of threshold exceeded which means too much air. With two spacers, the end of the O2 sensor also hit the top of the engine tunnel along one of the fuel or brake lines which I didn't like. It made the wire bend at a 90 degree angle which would eventually fail or rub a hole through the piping.

After a bunch of trial and error and bloody knuckles, I went with one spacer, undrilled, where I ground a slit into the outer shielding of the O2 sensor so it would seat completely into the spacer and no codes for 4 months.

As a side note, I can also hear the turbo spool up and the diverter valve more than I could before. Very present but not obnoxious. Just the way I wanted it. Good luck with your decision.

Doug

 

Hey Im debating on doing a test pipe to!! I have a Cold air intake and GIAC 93 CHIP!! Just wondering if with adding the test pipe you had to upgrade your injectors too?

Thanks

 

nope. the only time you gotta add injectors is when you add more air. a test pipe wont really add more air.

 

Actually your right but your wrong..

You will not need injectors but you are increasing the motors volumetric efficiency (or adding air). Test pipe reduces exhaust restriction which allowes for for better exhaust scavenging and improved exhaust flow. Since the free flowing exhaust allows for better exhaust gas evacuation you create a greater negative pressure differential in the combustion chamber (pre intake valve opening) which allows for more air to be forced in from the atmosphere and the turbo (which enhances the atmospheres psi). This is why you have camshaft overlap from the exhaust lobe and intake lobe.

A way to imagine it is that the exhaust gasses exiting the combustion chamber also pulls the atmospheric gas in. I have always thought of it as a train with the exhaust gas in the turbo manifold being the locomotive, the exhaust gasses in the combustion chamber being the cars, and the atmospheric gas in the intake manifold being the caboose (spelling on caboose?).

A test pipe works by reducing the psi seen at the backside of the exhaust valves due to significantly less restriction (not in the combustion chamber but in the turbo manifold) compared to the psi seen on the intake side (in the intake manifold). By reducing the psi differential you can accelerate the exhaust gasses faster in a given setup.

At the extreme end of this spectrum you get pumping loss which literally robs hp from your crank and happens when you have a greater psi in the turbo manifold compared to the intake manifold. This occurs when you push a turbo past its turbine peak efficiency which literally means there is too much exhaust flow and it can not flow around the turbine or out the wastegate fast enough. The higher psi of the exhaust gas in this situation literally spills back into the combustion chamber when the exhaust valves open and pushs down on the top of the piston which is transfered through the piston, into the rod, and back into the crank absorbing power from whatever other piston is in its power stroke. Most newer turbos does not have this problem but poor design and manufacturing can still generate this problem which can cause detonation and **** ton of other problems. The old Garrett T3 turbos with the stage 1 turbine are notorious for this. I have literally seen a loss of horsepower at the wheels on the dyno when going from 10psi to 18psi.

 

I feel like you're just splitting hairs now. The question was "will adding a test pipe require upgraded injectors?" and the correct answer, provided by redline, is no, because a 3" testpipe behind a stock turbo won't add enough flow to max out the stock injectors. The scenarios you're on about, while accurate, have nothing to do with this particular situation and therefore aren't really relevant to this conversation. Reducing restriction and back pressure is the whole point of a test pipe, I would hope the people reading this thread are already aware of that fact. Implying that you would somehow make more power on a GIAC stg. 1 with a 3" test pipe and 660cc injectors is just silly.

 

Our test pipe is 100% bolt on. I ran one on my old B5 A4 and instantly noticed the turbo spooled quicker and it had a little more top end.

Keeping the CEL off takes some tinkering with spacers and can be done. I never ran any spacers because the CEL never bothered me being lit up since it was on most of the time anyways haha.

Injectors are not necessary if all you're installing is this test pipe. Even with the combination of a chip, and full exhaust. Once you step up to a K04 it might require to you use something like TT 225 injectors depending on the tune.

Jason

 

ha. Funny thing I felt like somebody would call me out and say it will add more air. Its specifically why I stated "won't really add more air". Some people just always gotta get technical for no need