Sooty tail pipes
Safety Car
Joined: Dec 2004
Posts: 3,565
Likes: 5
From: stafford country, va. Avatar: Me on turn 3 @ Bristol (The World's Fastest Half-Mile)
Originally Posted by aaaaa
Help me understand; if these cars are tuned so lean why are my pipes black? I have a DIY CAI.
did you happen to notice if your pipes were becoming 'sooty' before you built your cai ?
oddly enough, i haven't noticed too many 'pure stock' vettes with 'sooty' pipes. maybe i'm wrong, i just haven't seen it.
i have noticed, and experienced, the exhaust 'tips' becoming blackened after the mod. bug bites.
more air requires more gas, more gas requires more aggressive spark/ timing ,etc.
i've lived with mine for about 2 years now, can't say i don't wish they would stay cleaner but on-the-other-hand, i'd rather it be a little rich than too lean, especially on the top end.
Race Director
Joined: Mar 2005
Posts: 10,399
Likes: 25
From: Austin Texas
The cars are designed to pass emissions tests at specific RPM and load, requirements are around a 14.7:1 A/F ratio. BUT; They are also designed to protect against Warranty damage so at full throttle open loop the A/F ratio can go as rich as 12:1.
Rich = Safer, cooler combustion, lower pressures and temperatures.
Lean = Dangerous, hotter combustion, higher pressures and temperatures.
Rich = Safer, cooler combustion, lower pressures and temperatures.
Lean = Dangerous, hotter combustion, higher pressures and temperatures.
Team Owner
Joined: Sep 1999
Posts: 20,054
Likes: 44
From: Swansea IL
For various reasons these cas are tuned "rich" from the factory. A rich mixture helps cool the cats and helps prevent pre-mature detonation. Most "tunes" are removing that fat and getting the AFR's UP to the ideal 12.7 - 13.5 range. My 03 Z had AFR's down to 10.3 after 5200 RPM. Talk about "rich" my exhaust pipes looked like a diesel within 100 miles. A tune would have netted me at least another 15 RWHP.
Tom
Tom
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CF Senior Member
Joined: Feb 2006
Posts: 23,313
Likes: 25
From: Tucson Arizona
My LPE 403 has the A/F ratio at 12.8/1 .... I clean the inside of my chromed Corsa tips out every couple of days. It doesn't look like a coal mine but hey....it's an internal combustion engine.
