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BLACK EXHAUST - for the thinkers

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Old 10-09-2004, 02:35 PM
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BLACK EXHAUST - for the thinkers

I was Wondering - if the black soot in the exhaust, which is normal for the rx-8, is due to unburnt gas and the air/furl ratio; then if it were to original spec (250 hp) before the revision, would it not dirty the exhaust.

i heard they made the air/fuel ratio richer to meet the emissions laws.

just a thought
Old 10-09-2004, 02:37 PM
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you would still have it, as the car burns oil as it runs.
Old 10-09-2004, 02:41 PM
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Wiping the soot off my exhaust pipes has become a morning ritual.
Old 10-09-2004, 02:44 PM
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The car does run richer, but in the high rpms. My car stock was doing 11 AFR at 6,000 rpm and upwards.
Old 10-09-2004, 03:13 PM
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How do we clean the soot we see out then? Just a paper towel on a cooled exhaust? Wheel cleaner? Chrome polish?
Old 10-09-2004, 03:16 PM
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I use chrome polish. But if you keep it clean on a regular basis, you can wipe it with a paper towel too.
Old 10-09-2004, 03:19 PM
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Originally Posted by Juxagent
I was Wondering - if the black soot in the exhaust, which is normal for the rx-8, is due to unburnt gas and the air/furl ratio; then if it were to original spec (250 hp) before the revision, would it not dirty the exhaust.

i heard they made the air/fuel ratio richer to meet the emissions laws.

just a thought
I thought running richer would increase pollution, not lower it.

Old 10-09-2004, 03:25 PM
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You are right Rob. Increasing the fuel to rich would increase pollution. The EPA folks don't care much until a vehicle exceeds the Fed requirememts so a vehicle that beats EPA they don't care. Have no clue of the rotarys and have not done any research but the engine is not a gas mizer and it runs on 91 Octane so the design and the fact that it throws oil into the intake to lube some moving parts is part of the soot issue in the exhaust. All cars get some sort of junk around the tail pipe. I guess cleaning it frequently is all we can do with the condition.
Old 10-09-2004, 03:26 PM
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Thanks again Jason. Liked the mirror video!!! Sound and all.
Old 10-09-2004, 04:08 PM
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Originally Posted by Juxagent
i heard they made the air/fuel ratio richer to meet the emissions laws.
Actually, they made it richer to lower the exhaust temperature to satisfy a *future* California requirement for catalytic converter longevity.

Pretty ridiculous, huh?
Old 10-09-2004, 06:20 PM
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I have a great brush I use on my rims / tires, and when I'm done doing that I stick the brush in my tailpipe and swirl it around a few times. No more black soot!

-Rupes
Old 10-09-2004, 06:55 PM
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Originally Posted by jtimbck2
Actually, they made it richer to lower the exhaust temperature to satisfy a *future* California requirement for catalytic converter longevity.

Pretty ridiculous, huh?
I thought it was a new EPA requirement of Cat life. I don't think they would have gone thru the 250/238hp SNAFU to satisfy a reg that didn't exist yet.
Old 10-09-2004, 11:22 PM
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Simple Green on a rag... wipe and drive away!
Old 10-10-2004, 08:45 PM
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running the car rich or lean is a way of controlling catalytic temperature which is very import for emissions. If the surface of the catalytic converter isn't the right temperature, the exhaust gases and air will not react on its surface and cause bad emissions.
Old 10-10-2004, 08:49 PM
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I spayed a small bit of wheel cleaner on the pipe ends and hosed it off and they wiped dry. It looks new again. This was on cool pipes. The soot is a known fact so we just have to keep the tips clean regularly.
Old 10-10-2004, 10:07 PM
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I use wheel cleaner on my tips as well. Been doing that for about 7 years with the FD. and the PFS exhaust. Works fairly well, but you have to keep up with it and do it every time you wash the car. Otherwise you have to use polish.
Old 10-10-2004, 10:11 PM
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I haven't cleaned my RX-8 tips yet, but I used to use Never-Dull on the racing beat exhaust on my FD. Worked great even when it was really dirty.
Old 10-10-2004, 11:17 PM
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i think the soot looks nice especially with my gold racing beat tips...
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