GT2rainge

Hi everyone i have a question about the colour inside the exhaust tailpipes.
My car is a 996 gt2 and the tailpipe used to always have a little bit of black soot in the tailpipe when on track,but recently i've had a remap and the tailpipe now looks a very light grey when on track pushing it. I'm just a bit concerned this may mean its running a bit lean or is thin normal when running higher boost/power.
Does anyone have any experience about why this might be?
Thanks for all suggestions in advance,cheers

911SLOW

Who did the remap ?

GT2rainge

Hi it was a friend in germany,his company is ruddel motorsport.
It now holds 1.0 bar boost which is not much more than standard but i need to change the wastegate actuators so may see more when this done. I got 566bhp on his rollers after remap,it was 493bhp before.
Why do you ask?

911SLOW

I don't know him so I can't say.
A quality map would help rule out leaning problems by definition..
I don't know what the black or grey reveals maybe nothing maybe the cats fried or the gas is bad or maybe you are obsessing with it : )

Anyway if you have durametric you can log the following values to be 100% sure everything ok.
Log:
RPM, injection time , MAF, O2 sensor values both banks, engine load, intake temp, ignition angle, boost pressure setpoint, boost pressure of sensor.
Then you can send the numbers to the programmer to verify everything checks.


John

GT2rainge

I must get myself a durametric do you know the best place to order one from,cheers

996FLT6

Did u use high octane leaded gas? Makes inside of pipe grayish. Mike

996FLT6

Of coarse can't use leaded gas with cats but if cat delete no problem. Mike

GT2rainge

Hi i'm just using 100octane shell v power,just super unleaded on the pump at shell stations here in uk,cheers

996FLT6

Sometimes tuners use high octane leaded gas to tune turbod cars. Don't know if they did but ne remaining leaded gas will leave gray residue. My friend's 450 whp evo8 was tuned with high octane leaded gas. But pretty sure not the case for u. Just giving out ne possible reasons. Mike

spare tire

I Use 100 octane unleaded straight or blended with 93 and my tips have a reddish terra cotta color on the inside of my tips. 996 gt3

GT2rainge

Cheers for the replies guys,i'm just worried it may be a sign of it running lean,

Macster

If the engine was running lean enough that the ends of the exhaust pipes were discolored I would expect the pistons would have melted long ago.

Different blends of gas, maybe even seasonal variations can account for some exhaust pipe exit color changes.

Or just the fact the engine is putting out more power and thus more heat and the extra heat is burning the soot that would normally be deposited at the exhaust pipe exits.

Sincerely,

Macster.

Q&A

i've always been under the impression that it's a good sign when the pipes are a bit light / white grey (mouse grey).
Most 997 GT3's i see after tracking hard have the same (easier to see with the 997 GT3 pipes, then the 996 turbo and GT3 chrome pipes)
When they are too black, the engine is often set up too rich (more petrol / less air) or not driven fast enough

FFaust

www.durametric.com Sorry to be so obvious, but they do sell direct.

At our last track event, a friend with a stock 7.2 GT3 RS commented on how clean his tail pipe was after the first session. Was similar in colour to what you describe.

John, love your new avatar. Seeing what you come up with next is almost reason enough to log on

J P Schnitzer

I wouldn't worry too much although from my perspective I always feel "safer" for some reason at the track with a stock ECU setting. I remember taking my Turbo X50 to the track quite a bit and I always noticed the exact same thing you are talking about....all the black soot would be burned away and you would see a whitish or slightly grey look on those tailpipe ends. That was with a stock ECU too.