Another stake in the heart carbon naysayers

[sakimano]

Very interesting read.

Are people surprised someone like Arthur is right, isn't he a professional engineer? As one myself albeit very early in my career I know how much knowledge an experienced engineer has and it's staggering. Trouble is engineers aren't respected as much as they should be.

Anyway that was off the point. Again, nice reading.

I honestly don't think it's anything to do with respecting or not respecting someone's engineering prowess. Plenty of engineers sat on the other side of the table and thought carbon was disastrous. Lots of them abandoned the scientific method and did no performance testing. Everyone equated 'performance' with 'dyno chart numbers'. Heck , they still do. This very forum focuses entirely too much on dyno numbers in my opinion. I'm far more interested in a proper test of acceleration. Whether we're measuring the performance that carbon may or may not rob us of, or the performance that a modification may or may not deliver us, I don't understand why we all worship the dyno chart.

Arthur did indeed propose real world testing with his 3rd gear test which wasn't bad really. I used to ask people to approach this scientifically by testing real world acceleration, just as I ask of the tuners who try to sell us tunes, exhausts and supercharger kits. Quarter mile times (trap speeds more realistically) are great information gatherers but most can't bother their arse to go...or don't live anywhere near a dragstrip.

Have a look at this. Here are the two most popular Audi forums on the planet. If you were to be looking at buying an RS4, and wanted to look into some info about the car, here is what is staring back at you, stickied top-dead-centre on each of them. THIS is why I think carbon is becoming far more of a story than it really ought to be. So many people are making it a story.

[ArthurPE]

actual time vs speed or accel is the only real parameter
in fact Audi has a chart that they use to evaluate a cars power
timed runs, various speed ranges, various gears
it was posted here by a Swiss member iirc

to me the times prove it and I reinforce it with a simple analysis of how much air is restricted by build up
the build up decreases area so marginally (vs lift and valve area-stem area) as to be insignificant
it may increase pressure drop a bit, but the air will accelerate, so net volume ~ the same, some slight pumping losses

I do agree that cleaning every 50-75k is probably good maintenance (just as the e46 M3 needs a valve adjustment every 25-30k)
not becasue of power loss, but to prevent a piece breaking off...although I do feel it is self limiting, anything could happen

[adsgreen]

Given the speed at which it returns if the problem wasn't self limiting all our cars would have grenaded by now.

[maxbhp]

Wow, quite the "stake in the heart"........thank God you're not a vampire slayer.

Saki, bite the bullet and open up your engine and clean the <beep> out. After 35k miles the crap is in there. Regardless of what impact you think it has on everyday driving/drag racing, the fact remains it robs you of some horsepower you paid the factory for. Maybe you drive your car in a way that you don't miss whats not there, and you won't notice a difference on your drag times and logs, but no good can come from dirty valves.

I have pre dynod, opened up the car and cleaned, then post dynoed 2 different times (one time the car did not even leave the Shop between the runs and was a closed cell dyno) and have come away with freed up horsepower. A clean after 17k netted me double what my clean 6k miles later got me. I don't care how you use your 'extra' horsepower, but if it's there for the taking why not have it? You paid for it.

Of course the people that say carbon build-up is the end-all of the RS4 and is a major nightmare are also exaggerating the problem, but it would be foolish to believe that carbon buildup doesn't steal power that this jewel of an engine should make, especially if you yourself haven't dyno'd, opened and cleaned the valves, then redyno'd your own car.

And I know your adversity to dyno's and all the variables but competent operators know what they are doing and it is a great way to compare hp gains, which is all I am talking about.

[ArthurPE]

the only dyno method worth a damn is steady state
ramp car up to a bit >power peak ~7700, and hold rpm as load is increased until rpm bogs to power peak, and hold for 10 sec or so to stabilize, then record
accel or ramp tests are not accurate nor repeatable
and do not have it dyno'ed by the same entity that you sold you a service that promised you more power via that service, self fulfilling prophecy

I'd like to see Saki's car cleaned, then run
my guess it won't best 12.75/108

[Brooner]

Regardless of which side your on we all know the engine does get carbon build up over time so it's just good maintance to get it cleaned that's my stance and will be doing it every 2 years while i own the car keeping it it the best condition i can for the future owner

[sakimano]

Wow, quite the "stake in the heart"........thank God you're not a vampire slayer.

Saki, stop being such a pussy and open up your engine and clean the <beep> out. After 35k miles the crap is in there. Regardless of what impact you think it has on everyday driving/drag racing, the fact remains it robs you of some horsepower you paid the factory for. Maybe you drive your car in a way that you don't miss whats not there, and you won't notice a difference on your drag times and logs, but no good can come from dirty valves.

I have pre dynod, opened up the car and cleaned, then post dynoed 2 different times (one time the car did not even leave the shop between the runs and was a closed cell dyno) and have come away with freed up horsepower. A clean after 17k netted me double what my clean 6k miles later got me. I don't care how you use your 'extra' horsepower, but if it's there for the taking why not have it? You paid for it.

Of course the people that say carbon build-up is the end-all of the RS4 and is a major nightmare are also exaggerating the problem, but it would be foolish to believe that carbon buildup doesn't steal power that this jewel of an engine should make, especially if you yourself haven't dyno'd, opened and cleaned the valves, then redyno'd your own car.

And I know your adversity to dyno's and all the variables but competent operators know what they are doing and it is a great way to compare hp gains, which is all I am talking about.

Yeah, those carbon nightmare people are exaggerating and are really strange aren't they?

Ummm...you just called me a pussy for not cleaning my carbon, then talked about dyno numbers for three paragraphs...then called me 'foolish' because I don't dyno and clean the carbon and dyno again. Basically because I don't do what you did. Really awesome input, thanks. Save the quattroworld attitude for quattroworld please. I don't even know who you are and I know you're in mick's pocket.

If you want to bring some facts to the table, please do. Just can the bullsh1t please.

Have you ever done ANY timed acceleration testing of your car? I mean I know you like to live your life one dyno run at a time, but have you honestly ever pboxed your car or taken it to a certified dragstrip before and after cleaning? That would be far more valuable information to people on this forum...people who like to actually drive their car, rather than live and die by dyno sheets (hopefully you now see the sarcasm and how dick-headish it looks when you pigeonhole someone based on one of the ways they test their car).

[sakimano]

I'd like to see Saki's car cleaned, then run
my guess it won't best 12.75/108

I think I am definitely down on power a bit. But as I have said above, I don't think it's enough to worry much about (and certainly enough to get called a pussy for).

A little analysis of my quarter mile acceleration times shows I'm giving up a little bit of power in the top end. Basically a tenth of a second or less. I see this by comparing the first quarter of the track and the last three quarters of the track. If I'm down a little bit of top end, that would make sense that it would show up in those last 8 seconds or so where I'm pushing through 3rd and 4th gear for extended periods of time in high RPMs (vs. 1st and 2nd gears where you rip through them in a couple of seconds each).

If conditions were excellent like they were when I went 12.75 @ 108.36, I bet I could go 12.69 @ 108.6X...but I agree, I'm not expecting 2 tenths and 1.5 MPH of trap speed that 20-30 whp should get me. That guy who I went to the dragstrip with this past weekend is getting carbon cleaned here soon. Hopefully we can go back and see what he is able to do cleaned. His car is basically stock as noted above, but for a small section of the stock catback cut out (the resonators) and replaced with an h-pipe for some sound.

p.s. here's his car and mine for anyone who wants to know what the ECS H-pipe on an otherwise stock car sounds like (his Phantom Black) compared to a completely stock car (my Avus Silver)

www.youtube.com/watch?v=fjdlEU483no

[RIV]

Sakamino your car looks well slow in that clip, I reckon you have some carbon issues!!

[sakimano]

Sakamino your car looks well slow in that clip, I reckon you have some carbon issues!!

lol bugger

[Coaster]

Great article and very well written. I couldn't agree more. This is panic fever and there are two things that spread it like wild fire; people who worry about their cars and the internet.
EXACTLY the same thing with rear subframe mounting failure chat on E46 M3s.

[sakimano]

So my mate who ran 13.06 @ 107.6 last Saturday got his car carbon cleaned yesterday. Here's his post from audirevolution with his impressions and some pictures.

55,000 miles and never cleaned before this. Not bad looking, but certainly plenty of carbon there. He is planning to go back to the dragstrip soon (Wednesday maybe) so we will see what happens.

[quote author=Mistro link=topic=1077.msg24745#msg24745 date=1345748895]
When I first got my car I was worried about performance loss due to CB but I stopped worrying after a while.

Just had mine cleaned yesterday with 56,000 miles on it since I was worried about any bits of carbon flying off into the cylinder.

I can't really tell with my but-dyno about whether there's any difference, but I can say for sure that there is no shuddering during a cold idle now and the car feels smoother overall.

How bad does this look?

Full album: imgur.com/a/PNvJn









[/quote]

[Timster]

Have seen a lot worse than that before !

[JCviggen]

Admittedly I skipped through the post a bit quickly but I am somewhat confused as to what has suddenly been proven or debunked.

2 stock RS4s got good numbers at a drag strip. Not much to say especially with no after comparison avilable yet. Your buddies intake pics didn't look particularly bad but certainly not 100% what it should be. Would be surprised if cleaning nets him more than 5-10hp extra.

Run a car "properly fouled" at a strip and come back after it's been cleaned and we might learn something. Maybe. From the trap speeds.

Looking at some of the pictures I cannot imagine that the very fouled inlets I have seen here before (a magnitude worse than your friend's) are not robbing a good deal of power. The total diameter of the ports has significantly decreased in those cases which almost certainly must lead to considerable VE losses at high rpm (not so relevant at low RPM I imagine but these engines are high strung)

BTW, is it my poor eyesight or does the left car appear to be on larger wheels? (something that makes a small difference as well)

Anyway, interesting material. I'd prefer autobahn runs over drag strips but I realize it's just not available on your side of the pond. RS4 does IMHO belong slightly more (not quite either) on an actual racetrack with corners than a half mile worth of straight sticky tarmac.

[sakimano]

Read the whole post first. Less confusion that way.

1. I addressed the fact that truly carboned up cars are likely down a noticeable amount vs a negligible amount of power loss...i.e. High mileage cars. I was talking more about the 30-50k mile cars not being all that affected and the fact that cleaning every 10,000 miles a some advise is excessive to this end.

2. The quarter mile is an acceleration test. We are using it as a measurement of how our cars stack up to clean cars that were tested by periodicals when the platform was launched , or by other rs4 owners. Some use the dyno to measure power...and I am sure Audi didn't design the car for the dyno, but I don't see you giving your opinion that it wasn't designed for the dyno in those threads? A road course excursion is a fun time but useless for measuring acceleration. Useless. I don't even know how that comment you posted was relevant?

3. Both cars are on stock wheels. Avus car has the rs4 ti package wheels 19x9 255.35.19. phantom car has rs4 silver wheels same size, same tire size.