Another stake in the heart carbon naysayers

[sonny]

The drivers weight

[lexos]

just some comments:

after the cleanup....two solutions

- install a catch can and remove the stupid part from Audi (and close the pipes as well).

- keep the audi part in place, so it will "act" as a catch can but close the main pipe (so no vapor oil coming back to the admission), so no need to worry about the a catch can installation.

[caldy]

Already tried a catch can - doesn't catch anything worthwhile.

[RS4pete]

A 3k to 8k run (in absence of VCDS which most don't have/use) relies on the driver using the lap timer accurately or at the very least constantly.

I understand the real world argument for carbon not being a massive issue, hence I wouldn't get mine cleaned.

If it we're say an issue affecting my race bike then yes, I'd clean the hell out if it. But it's not. We're not pro racing drivers and as real world proved its impact is minimal and nowhere near significant enough to worry. Therefore it's down to individuals to decide if circa £800 for a clean is a worth while. If you can do it yourself then happy days.

I know that if I had £800 in the bank to make the car quicker I'd invest it in me and take a 'Californian super bike school' type course.

[RS4pete]

.

[rugbybloke]

I simply dont get how you can say its not a "real world" issue. I am no racing driver and have never tracked my car but the improvement in day to day driveability is dramatic. The car is noticably less lumpy during cold starts and pulls much stronger higher up the rev range. I am also seeing an average increase of 2 mpg on my regular commute to work. I have yet to re dyno the car since the work was done but aim to do so soon and will post the results.

[bam_bam]

just some comments:

after the cleanup....two solutions

- install a catch can and remove the stupid part from Audi (and close the pipes as well).

- keep the audi part in place, so it will "act" as a catch can but close the main pipe (so no vapor oil coming back to the admission), so no need to worry about the a catch can installation.

i thought the issue was mostly due to blow-by, not oil.

[adsgreen]

just some comments:

after the cleanup....two solutions

- install a catch can and remove the stupid part from Audi (and close the pipes as well).

- keep the audi part in place, so it will "act" as a catch can but close the main pipe (so no vapor oil coming back to the admission), so no need to worry about the a catch can installation.

i thought the issue was mostly due to blow-by, not oil.

The build up is most likely valve overlap from internal exhaust gas recirculation. There is *nothing* you can do to prevent this unless you can change the cam timing profile and the ECU logic controlling it. However then you are in another world of issues as EGR is pretty important on it's own.
Failures of other bits can cause oil to get in but I doubt *everybody* has a faulty car.

[adsgreen]

I simply dont get how you can say its not a "real world" issue. I am no racing driver and have never tracked my car but the improvement in day to day driveability is dramatic. The car is noticably less lumpy during cold starts and pulls much stronger higher up the rev range. I am also seeing an average increase of 2 mpg on my regular commute to work. I have yet to re dyno the car since the work was done but aim to do so soon and will post the results.

I don't put much stock in feel purely because it's too easy to be clouded. I've met people who insist one brand of fuel is better than another purely on feel... now the key point here is they said this straight away after filling up. Even the best ECU's would struggle to make anything of a fresh tank of fuel without some degree of learning.

2mpg could easily come from the much colder weather or the aircon not tripping. There's just so many factors at play that it's hard to take them out.

I'm not saying there isn't a difference (as there is) but it's not something I'm getting hung up about. Have I had the carbon cleaned on my car? yes - but that was because the manifold flaps had failed so the IM needed to come off anyway. In this case you might as well get it sorted.

[ArthurPE]

An interesting development in this thread...
the two cars in question (my still bone stock RS4 and the recently carbon cleaned RS4 from the OP) went back to the dragstrip yesterday with a local Audi group. The temperature was near freezing, the density altitude was around -800 feet most of the day...so conditions for making power were great...and that showed up in the results.

Some interesting results.
My best elapsed time - 12.83 @ 109.2
My best trap speed - 12.85 @ 109.9

Back in April, I went 12.75 @ 108.3 MPH. Traction was WAY better that day, with me cutting 1.82-1.83 sixty foot times. This time unfortunately I was more like 1.87-1.91 all day. For reference on our quattro Audis, we gain a tenth in the full quarter mile when we shave a tenth off the first 60 feet, which really measures the time you take to get through first gear. At 60 feet we're going around 35 MPH or so.

The other car, has had a few modifications. First, here's what he had back when we did the original carbon clean test:
ECS Hpipe exhaust crossover in lieu of the resonator section of the stock exhaust. This is a minor help for power, mostly it's just sound. He had this on the original before and after.
JHM intake phenolic spacers - he installed these when the manifold was out.

That was it back then. Since then he has added
KWv3 coilovers, lowering the car a good 2" (from the looks of it compared to mine)
Piggie pipes - basically he gutted the PRE-catalytic converters, up close to the end of the headers where they mate up with the downpipes.

So to recap, yesterday my best was 12.83-12.85 @ 109.2-109.9.
Yesterday HIS best was 12.47-12.53 @ 113.7-113.8
!!!
Pretty huge delta. This is important for two reasons:
1. the carbon clean + piggies + intake spacers + being a little lowered = around 0.4 seconds/4 MPH gained over a quarter mile...pretty significant
2. the RS4, in the hands of decent drivers with decent mods, is running QUITE strong compared to other platforms.
As in the previous thread, I remain unconvinced that carbon cleaning is drastic and transforms the car....but I certainly think it has an impact on top end. Break down that delta however you want, just thought I would share.

so 3 to 4 mph and ~ 0.35 sec, 2 to 3%, which would imply ~the same HP/torque increase
whose car is lighter? (options, driver, etc.)
does he have software?
what tires do each have and what running pressures?
what were his 0-60' times? I'm thinking the lowering helped the car dig/launch better, if not in time, in velocity...less transfer of weight, etc.
the spacers/gutting definitely help top end a bit, but at the expense of efficiency, and in the US at least, legality

if you look at previous before/after times and these, the de-cat and suspension made all the difference

I think the carbon is primarily valve stem seal leakage (as in all cars) but unlike non-DI cars ours do not wash it away
the internal egr bakes it on

[sakimano]

Interesting, I would say the gutted pre cats was the biggest performance enhancing mod there. What was the mileage of yours and his car out of curiosity?

My car 42,000 miles, never cleaned
His car around 60,000 miles, cleaned 2.5 months ago

I simply dont get how you can say its not a "real world" issue. I am no racing driver and have never tracked my car but the improvement in day to day driveability is dramatic. The car is noticably less lumpy during cold starts and pulls much stronger higher up the rev range. I am also seeing an average increase of 2 mpg on my regular commute to work. I have yet to re dyno the car since the work was done but aim to do so soon and will post the results.

I don't put much stock in feel purely because it's too easy to be clouded. I've met people who insist one brand of fuel is better than another purely on feel... now the key point here is they said this straight away after filling up. Even the best ECU's would struggle to make anything of a fresh tank of fuel without some degree of learning.I'm not saying there isn't a difference (as there is) but it's not something I'm getting hung up about. Have I had the carbon cleaned on my car? yes - but that was because the manifold flaps had failed so the IM needed to come off anyway. In this case you might as well get it sorted.

So many people say the 'feel' is a huge change, and I don't doubt them. Especially when you are talking about your daily driver...any little change you are likely to feel and have it feel exacerbated. It's like having a haircut or a pimple on your face...you REALLY notice it because you see your own image so many times a day (but most others would never notice the change).

What is debatable is not whether there is a perceived change, because by almost all accounts, there is. However what we want to understand is what that perceived change translates to in actual performance, when measured. So far, I can't see much evidence for it changing a pretty good test of performance, the quarter mile. A rip through 4 gears from 0-110 MPH. Perhaps it's good for 1 tenth and 1 MPH on most cars, and 2 tenths 2MPH on a bad case? Certainly not enough for anyone to really sweat it out.

For most people, if I told them that from this spot here, to that spot there 1320 feet away, you will get there one tenth of a second sooner, or the equivalent of a car length, but ONLY if you give me $1000...I reckon they would laugh in my face and peel out without taking the deal. That's effectively what a carbon clean is, measured in performance. Of course in feel, it may be well worth the $1000.

so 3 to 4 mph and ~ 0.35 sec, 2 to 3%, which would imply ~the same HP/torque increase
whose car is lighter? (options, driver, etc.)
does he have software?
what tires do each have and what running pressures?
what were his 0-60' times? I'm thinking the lowering helped the car dig/launch better, if not in time, in velocity...less transfer of weight, etc.
the spacers/gutting definitely help top end a bit, but at the expense of efficiency, and in the US at least, legality

if you look at previous before/after times and these, the de-cat and suspension made all the difference

I think the carbon is primarily valve stem seal leakage (as in all cars) but unlike non-DI cars ours do not wash it away
the internal egr bakes it on

for your questions

1. both about the same weight. I weigh about 40 lbs more than him, but my car, like your car, doesn't have the premium package (has sunroof though) so I don't have the rear window sunshade. When I weighed my car it was 3938 with a full tank and me NOT in it. That's pretty much within 10-20 lbs of every RS4 I've seen weighed. So weight if anything is in his favour by about 20, but not enough to notice. I also am pretty vigilant about getting everything out of the car before I go to the strip. I'm not sure if he does the same (i.e. I get rid of the tool kit, the tire inflation kit, and any loose stuff I have in the cabin of the car. My car is as light as I can get it while still being absolutely full interior etc.

2. no software on either car

3. same tires installed at the same shop within the last month ironically, same pressure (Michelin Pilot Super Sports, 255.35.19 on stock wheels, both at 38 PSI).

4. His 60 foot times on the day were a bit better than mine, but not much. His best run he had a 1.83. My best run I had a 1.87. Track printouts below. I'm 4591, he is 4594

[andymc]

interesting Carbon chatter.

I'd read through most of the Carbon threads over the past 12 months and decided its a <nothing> item.

For whoever reason I went to MRC and talked with Doug. 1 thing led to another and I thought I'd share dyne results from a non-believer:

prior to Carbon clean - 356ps 422nm
then MRC Carbon Clean and replacement panel Filter
post Carbon clean - 412ps 466nm

interesting ?

[sakimano]

interesting Carbon chatter.

I'd read through most of the Carbon threads over the past 12 months and decided its a <nothing> item.

For whoever reason I went to MRC and talked with Doug. 1 thing led to another and I thought I'd share dyne results from a non-believer:

prior to Carbon clean - 356ps 422nm
then MRC Carbon Clean and replacement panel Filter
post Carbon clean - 412ps 466nm

interesting ?

interesting for sure, but I don't drive my car on the dyno...so I'm not so certain what 56 dyno HP means in the real world.

I also don't put much stock in dyno info when the guy being paid for the carbon cleaning is the guy who wrote his own report card to tell you how he did. I don't doubt MRC at all, but a dyno at a tuning shop is like a pen to me...and after a number of years of modifying cars and seeing all kinds of dyno shenanigans, I have completely tuned it out (pardon the pun).

I think performance data is far more relevant, especially when it is gathered by us, for us.

[andymc]

And I'm sure the positives & negatives of Dyno vs Drag will go on for years.

Albeit not an expert I feel the variables of a trusted dyno gives more consistency than drag times by different cars. Maybe thats just the Euro way as we're not as passionate about Drag strips as our colleagues in US.

I do relate to your comments about tuning shops and a 'pen'. In my experience the first set of data was purely a 'health-check' run and 'cleaning' was not on my agenda at all. It was some weeks later before the car went in for a clean and re-check at the same place.

[sakimano]

And I'm sure the positives & negatives of Dyno vs Drag will go on for years.

Albeit not an expert I feel the variables of a trusted dyno gives more consistency than drag times by different cars. Maybe thats just the Euro way as we're not as passionate about Drag strips as our colleagues in US.

I do relate to your comments about tuning shops and a 'pen'. In my experience the first set of data was purely a 'health-check' run and 'cleaning' was not on my agenda at all. It was some weeks later before the car went in for a clean and re-check at the same place.

all good points

For me, the dragstrip is such an easy thing to do, and is a great measured performance test. We have a half dozen major automotive publications that do thorough performance tests of just about every interesting new car under the sun..and they always do acceleration testing, including the quarter mile. It's a gigantic database of benchmarks for you to compare your car/ mods to. Further, we have a quartermile database on another site where everyone posts up their times, and they're added up. Another great way to compare your modded car to other modded cars. B5/6/7/8 are all on there.

Every manufacturer on earth releases 0-60 mph (or 100 kmh) and often 0-100 mph type data. The dragstrip is a nice standardized way for you to test your car at what one of the major reasons you bought it for...going fast! I'm talking strictly about measuring power and not handling of course. Not too many people dyno for handling though