Pics of my carbon build up!

[Steve_C]

IIRC, I was taking 9.0-9.5 secs for the 3k-8k run. Am now taking 7.9 secs.

What measuring device were you using Steve?

Using the on board lap timer. Whilst I accept this is not necessarily accurate in absolute terms I was careful to be consistent to ensure starting errors and stopping errors cancel out. This obviously means I may have been measuring 2.9k - 7.9k or 3.1k to 8.1k but the reduction in times of ~1.5 secs should be fairly valid.

I think Arthur previously calculated for me that 7.9secs for an Avant running 434PS was about right based on his wealth of data?

[neckarsulm]

Using the on board lap timer. Whilst I accept this is not necessarily accurate in absolute terms I was careful to be consistent to ensure starting errors and stopping errors cancel out. This obviously means I may have been measuring 2.9k - 7.9k or 3.1k to 8.1k but the reduction in times of ~1.5 secs should be fairly valid.

I think Arthur previously calculated for me that 7.9secs for an Avant running 434PS was about right based on his wealth of data?

fair point. Would be interesting to see how quickly times go back up when it gets dirty again.

It would be good if there was more talk of a permanent fix than this temporary cleaning which doesn't fix the problem.

[Steve_C]

It would be good if there was more talk of a permanent fix than this temporary cleaning which doesn't fix the problem.

Absolutely, but in the meantime it'll just have to be a regular Italian tune up!

[HYFR]

Previous owner did 20k miles pa for 3 yrs. Mostly sitting at 3500rpm on the motorway. Serviced by Audi on long life approx every 12 months.

so did my old one, but still pulled 380PS on MRC dyno

[Steve_C]

Previous owner also said most of the time the car was run on normal unleaded rather than V power. Could this have had an effect?

[HYFR]

Yes, a bigger effect over those miles I'd imagine

[droll]

sorry for my ignorance but how would bad fuel contribute to the CB if the fuel is only injected into the combustion chamber and has no chance to clean (or dirty) the valves?

i've read a lost of posts on the CB but can't quite get my head around 2 things: the above and how revving to 8k etc would also reduce the buildup issue (since this makes the engine hotter and the oil hotter which would mean cooking the oil and contributing to more carbon)??

[2manytoys]

I'm surprised this is still being debated.

I don't think any amount of "good" driving is going to keep the carbon at bay. I suspect the problem is valve stem seals. In fact, I've recently seen the inside of a 2.0T with 80,000km (about 50,000 miles) where oddly No'1 cylinder valves weren't too bad, but; 2, 3 and 4 were very bad. Head off, a clean and new valve stem seals and the car is back on the road with improved top end.

I'd probably say that those getting bad carbon buildup will probably be in the same situation in a year or so (maybe 12,000 miles or so) after the clean. Once the seals are worn the problem is going to get worse and happen faster.

Anyway, anyone interested in some dyno graphs and timing information about what carbon can do should have a look here: http://www.audizine.com/forum/showthrea ... and-graphs

[neckarsulm]

I'm surprised this is still being debated.

I don't think any amount of "good" driving is going to keep the carbon at bay. I suspect the problem is valve stem seals. In fact, I've recently seen the inside of a 2.0T with 80,000km (about 50,000 miles) where oddly No'1 cylinder valves weren't too bad, but; 2, 3 and 4 were very bad. Head off, a clean and new valve stem seals and the car is back on the road with improved top end.

I'd probably say that those getting bad carbon buildup will probably be in the same situation in a year or so (maybe 12,000 miles or so) after the clean. Once the seals are worn the problem is going to get worse and happen faster.

Anyway, anyone interested in some dyno graphs and timing information about what carbon can do should have a look here: http://www.audizine.com/forum/showthrea ... and-graphs

Is the fuel or oil quality of Australia or USA significantly different to ours thus negating the scientific element of any comparison with ours?

[2manytoys]

We use Shell Optimax 98 RON and Castrol SLX Professional Longlife III. http://www.castrol.com/castrol/extended ... Id=7061123

I don't think it's fuel, but it could be oil?? Maybe those that don't have a lot of carbon don't have worn valve stem seals. Maybe a different oil could help to prevent the valve stem seals from wearing, hence less carbon, but who knows???

[neckarsulm]

Maybe a different oil could help to prevent the valve stem seals from wearing, hence less carbon, but who knows???

Only she knows (the carbon fairy)

[sonny]

LOL +1 to the Carbon Fairy.

[2manytoys]

haaaaaa can you get them as bumper stickers?

[neckarsulm]

haaaaaa can you get them as bumper stickers?

....the stickers are going to be supplied free with each clean up, redesigned like Ghostbusters logo - circle with a red X over the top of the fairy and slogan of "I aint a fraid of no soot"

[Steve_C]