The Dangers of Running Open Downpipe

[gsxAWDdsm692]

I was just wondering what is the best way to work with the rear O2 sensor when you are running an Open downpipe? Like what is the best way to keep your car from messing up in any way...I know i might run rich but i want to to know if their are any dangers of running with an open downpipe? and if i have the rear o2 sensor in or if i do not? I started it up last night in my buddies garage and it was way to loud to be driven on the street...but we did anyway @ 12:30 in the morning ill have a video up soon if anyones interested...thanks

 

[Talesin]

The only thing the rear O2 does is make sure your cat is working, and throw a CEL if it's getting funky readings. If your FRONT O2 went bad or was disconnected, you'd get crap gas mileage due to a bad air/fuel mixture. Only thing not having a rear O2 will do is again, toss a CEL.

If you're running particularly lean or rich, you might worry about anything on the undercarriage that could be melted by 1400*F exhaust gas under full boost. Beyond that, noise regs and low/mid-end torque loss due to no backpressure are your only real worries.

 

[gsxAWDdsm692]

Yea i hear you on the melting my undercarriage. So the rear O2 sensor is basically pointless in the sense of air/fuel ratio? I am not boosting my car anyway im just impatient and awating the cat back in a few days. I know boost creep can be a factor from runnin open 3" downpipe... Would high boost levels like redline cause some trouble to my motor? i am not too sure

 

[PieEyedPiper]

The only thing the rear O2 does is make sure your cat is working, and throw a CEL if it's getting funky readings. If your FRONT O2 went bad or was disconnected, you'd get crap gas mileage due to a bad air/fuel mixture. Only thing not having a rear O2 will do is again, toss a CEL.

If you're running particularly lean or rich, you might worry about anything on the undercarriage that could be melted by 1400*F exhaust gas under full boost. Beyond that, noise regs and low/mid-end torque loss due to no backpressure are your only real worries.

http://dsmtuners.com/forums/showthread.php?t=168578

 

[cb3016]

also big boost creep issues could arise if your not using external wastegate

 

[Lordpaxin]

I am gonna put back on my stock exhaust apprently I am losing the Torque I had when i Upgraded to 3 inch. no wonder it feels slow........

 

[Spoolin4Ever]

I am gonna put back on my stock exhaust apprently I am losing the Torque I had when i Upgraded to 3 inch. no wonder it feels slow........

noway you got to be kidding

 

[Lordpaxin]

I think i was kidding, though I dont know what setup I had on the car at the time.

HECK i dont remember writing that post!!!!!

 

[DSMunknown]

According to the link below, an open cat-back exhaust system performs nearly identical to an upgraded cat-back system. I'm not sure if the test was including a catalytic converter in both examples, but I would assume that they were. Obviously, a cat will be much more of a restriction than working with an open DP.

I wonder how well (just looking at numbers) an upgraded test-back exhaust system would measure up to an open DP. My guess is that it would not perform as well overall.




http://www.jumptronix.com/2g_go_faster/Stages/details/CatBack.htm

 

[Low Impedance]

. Beyond that, noise regs and low/mid-end torque loss due to no backpressure are your only real worries.

that is a false staement. "needing backpressure" is basically a lie. A turbocharger generates backpressure as it is, hense it acting as an effective muffler. A car without a turbocharger still doenst need backpressure. Its the design of the header/exhaust that is important.

 

[white_dsm]

How bout just d/c the downpipe and moving it away from the o2 instead of removing the whole exhaust?