Thanks for the replies everyone. Just some background on why I'm so cognizant of the soot, and it's not because I'm a concours disciple!

Back in the fall of 2007, a friend and I both picked up brand new 3.4l Cayman S's at the same time.

I noticed that from day one that his exhaust was extremely sooty and mine was clean. Fast forward 5 years and 30K miles later, he was installing a new engine outside of Porsche warranty to the tune of $25K thanks to a scored cylinder that was probably present from day 1 and got worse according to the tech. My car kept going until last year at 62K miles when it was traded for the GT4.

My friend's car always did use more oil than mine and usage it got progressively worse. It was still within the scope of Porsche parameters so the dealer did nothing during the warranty period. His car was only street driven and never tracked.

Another Cayman S friend who had consistently dark tailpipes on his 2007 eventually required a rebuild of his engine but he was a heavy tracker and I guess that's just par for the course.

This is why I'm always looking at tailpipes.

 

Pete,

This being an apparent standard characteristic of DFI engines aside, if you're concerned about potential warranty issues down the line, then start leaving a paper trail with your dealership now. If something fails outside of warranty, and you can point back to your attempts at getting it fixed or looked at in retrospect, you'd have a better chance of having the work covered.

 

Good advice. Thankfully nothing of real concern for now, 6500 miles and still going!

 

Too bad about your friend and his unfortunate luck with his Cayman engine.

I dare say the extra oil consumption had nothing to do with the extra soot, if there was any extra soot. My Boxster's exhaust outlets have been black with soot forever. Same with my Turbo's exhaust outlets. Over 300K miles on the Boxster and over 145K miles on the Turbo.

For every gallon of gasoline burned the engine produces around 19lbs of carbon some of it in the form of soot. A bit of oil being burned is not going to add to that 19lbs in any meaningful way.

Besides as the Porsche techs point out there are a couple of converters between the engine and the exhaust outlets and any soot issue there is probably more a reflection of the converters' performance rather than the engine's.

So, no CEL? No untoward engine symptoms? No problem. Soot happens.

 

Based on a 75 mile test today in my BS that began with clean exhaust tips, I can say leaving sport mode off does decrease the tailpipe soot buildup. Too early to tell if it eliminates it or almost completely eliminates it, but there is definitely a correlation to sport mode on and seeing soot buildup. I never thought about trying this test until I read your quoted post. My tailpipes were as clean at the end of 75 miles without any sport mode as they were when I started out this morning. I've done the same drive after a detail job and using sport mode frequently as I usually do, I saw very noticeable soot buildup.

Caveat....this is not a scientific experiment, anecdotal information at best.

 

Are you sure about that weight? Can you provide references for that? Not being sarcastic or overly critical, it's just that at first glance, that number doesn't seem to make sense. Could it be more like 1.9 pounds?

A gallon of gas (US) weighs about 6.5 pounds. And, when combusted, a significant portion of that gasoline is turned into water vapor. So, while there are a lot of carbon compounds being created in the combustion process, I just find it a little hard to believe there are three times the mass of carbon compounds coming out than went in.

 

I noticed today in PP pictures from the Watkins event that alot of the CS's had whiteish tips. i know race cars have this becuase they are running "perfect"tunes, but these race teams are running our same engine .. does it just come down to tune?

 

Macster is correct 19 pounds:

http://www.slate.com/articles/news_a...comes_co2.html

 

Okay, thanks. Learned something new today.

 

My guess is that the white tips have to do with extended heat from track running. My friend's 991 GT3 would have white tips after each track session but I never see this when the same car is street driven.

 

How about 19 pounds of carbon *compounds*, not just plain ol' carbon.

 

Here's what the tailpipes look like after 148 miles of driving since detail job, all miles without sport mode. I'll drive the next 75 miles or so with frequent use of sport mode like I usually drive and post a picture. It's a BS and not a GT4, but the results might be somewhat relevant to the 3.8L, I suppose.

Look much cleaner than I recall after my typical 150 miles of driving with lots of sport mode engaged.

 

I have 500 miles on my car now and will go out to garage and use a paper towel and report on my soot

Stay tuned

Okay - Update - so 500 miles and 300 miles after detail and PPF. Almost no soot around tips. Car also never smokes and 3 Porsches before this always smoked. This car has not farted once. To be quite frank - actually concerned. Not typical for a Porsche. I hope they did not put in a VW engine

 

Hmm.. Is all the black soot-like stuff all over the car just actually brake dust and not exhaust soot?

 

So at 3 years or 30,000 miles have the dealer change your spark plugs and bore scope the cylinders while the car is still under warranty. This will show any issues and give you piece of mind going forward.
Cman21