Dragstrip visit + Interesting logging results

B6/7 S4/RS4
#21

I’m with you there…that’s just frigging weird.

Of course we didn’t dyno Mistro’s car…maybe it would have dyno’d equally?

As for the other cars, some of the guys with 70,000 or 90,000 miles…I’m reasonably sure they’re down on power enough to show up in testing. Not sure how much, but in theory, it must be. My whole ‘thesis’ if you would call it that despite the less than scientific testing, is that the guys who say things like

“the RS4 needs a carbon clean or it is basically a 4.2 S4 or S5 fast”
“carbon means the RS4/RS5 is a complete non-option because it robs you of so much power”
“you have to carbon clean every 5 to 10 thousand miles to have the car running otherwise it is way slower”

I think that’s all bullshit, based on my experiences.

My Rs4 has never been cleaned (I confirmed this with the previous owner and the Audi dealer he had it serviced at when I didn’t believe him after I ran 12.9 last year) and if my car lines up with an S5 or S4 4.2 I wil FUCK IT UP. Last night I put 12 car lengths on an S5 with an exhaust and MT6. All of those guys making these claims about the RS4 either don’t own one or don’t test the one they do own properly.

#22

This is really fantastic info and I’ll definitely admit I am surprised regarding the carbon clean benefits. It seems likely that the carbon build up must be just to the point of causing misfires before measurable performance is lost. Makes me that much more interested in looking our for RS4s for sale down the road a bit.

In regards to the B8, that is certainly faster than your stock RS4, no question. I also love that your 60’ times are within 5/100ths. However in terms of cost/benefit, it does seem likely an RS4 with JHM tune and piggies could potentially be right on the rear bumper of that B8…

#23

With a JHM tune and piggies, I reckon my car would run 12.5 with ease. My goal originally was 12.40 or better @ 110 or better with a tune + piggies + stock catback, once I get around to modifying the car. I think that is a very modest goal to be honest.

Not sure you noticed but elevens ran 12.5 @ 110 in his RS4 with nothing but a GIAC 93 tune. So the RS4 certainly responds to mofidications VERY well. Other than the ‘just a REVO tune’ (REVO 93 really kicks some ass) I think the RS4 stacks up mod for mod . well…that’s not what I think. That’s what I know having tracked the quarter mile times for both platforms here. The B8 seems to respond to race gas better, but for 99% of us that is irrelevant other than when shooting for fun and records. When comparing cars door handle to door handle, just about nobody is running race gas full time. Even then…a non-tuned RS4 with LW rotors/seats/flywheel put race gas in his car, and ran 12.2 @ 112 a few weeks ago, so again, maybe the B8 doesn’t have an advantage. That’s only what…4-5 tenths off the fastest B8 S4 out there…a car with over $10,000 in mods (while that RS4 has about $3000 in mods).

audirevollution.net/quartermile

#24

I put together a spreadsheet of the ones from the last time out. I remember seeing the same pattern from then too. My second run would always be the faster one. However the overall trend was slower times as the day went on. Yesterday, it seemed like the times trended pretty flat, but it was also cooler.

I’ll check later today.

I’m actually kinda curious to see what it dynos now. Maybe we should bug vagkraft into organizing another dyno day lol. Here’s the video from last time. The graph is at the end.

http://youtu.be/-WqSrA-chZU?hd=1

That Pauly D guy?

Funny thing is the first misfire I had on this car was the day after the cleaning, never before.

#25

No, I hadn’t seen that yet. Encouraging for sure.

Random aside, I had no idea the TTS kit was 13 lbs. of boost. Yikes, that seems like a lot for a 12.5 CR motor. As long as it proves reliable, then that’s all that matters. But I’d be a little nervous I think.

#26

Well, the internals are very strong. More of concern would be if they were moving irresponsible power/torque through the engine. They’re ‘only’ making around 480-500 whp and 380 WTQ though…and it doesn’t slam like a turbo hit, being a cfuge.

#27

Yeah I think the ultimate test would have been to do a before and after dyno test as well as the track to debunk the carbon myth.

I just dont see how carbon built up on the valves and such would cause such a dramatic decrease of power that people claim. Until the dyno thing comes to life Im still kind of iffy on the subject… but then again we saw how inaccurate the dyno is with the m90 so maybe carbon has some sort of effect on how the dyno interprets the calculation.

#28

the dyno would likely show a delta that was significant. That’s what we’ve seen hundreds of times already.
He has a ‘before’ dyno. Not sure the dyno is a very effective test though as it just proves that ink sticks to paper…and costs $100 around here.

#29

No Im not saying its effective at all in fact Im agreeing that its a terrible way to test the true power of your car. I would just be curious to see the results of the track versus dyno data. I would bet that a nice increase of power would be seen after the carbon cleaning like we have seen countless times before.

If this is true then I personally would never trust a dyno again (even though I dont really as it is)

#30

While I understand the issues associated with dynos and using them as “absolutes” for performance gauges, I do think that they have their uses and are an important measurement tool in their own right.

However, in order to be scientific about it, if you were going to use strictly dyno numbers to make an “a” to “b” comparison, you have to eliminate ALL variables except for the one you want to test for. Meaning, if you want to prove that changing your intake gave you an extra 50HP, then you must use the exact same dyno, with the exact same ambient conditions, exact same tyre pressures, exact same engine temp, fuel level, etc etc. The only thing that can change is the intake in order to have a true cause and effect relationship.

And because of this, dynos are inherently inaccurate since you almost never have all of the EXACT same circumstances except for one variable. But, they do still give us some kind of benchmark by which to compare things. ;D

End of blathering. Sorry bout that.

#31

Here are the runs from the first time around. Second run always had a faster trap, but ET got worse.

http://i.imgur.com/5O9yz.png

Unfortunately not as many runs this time around to get a consistant trend, although it’s interesting that my slowest ETs got the fastest traps this time around. Why would that be?

http://i.imgur.com/1OhLB.png

#32

I don’t think that dynos are inaccurate. They are just WAY easier to manipulate to say what you want them to say, since there is a computer between your car and its performance measurement. And VERY often, the place that performs the dyno testing is the same place that performed other services, so the tendency for skewing results is high. If you had places that offered to “prove” their work with a drag strip time sheet before and after with your vehicle, I bet they would be sandbagging it on the before trip, or using race gas on the after, or both.

The same conditions that help/hurt a dyno run also affect a drag strip run - ambient temperature, humidity and pressure, tire pressures, engine temp, fuel level, etc. It’s not the dynamometer that lies; it’s the people who operate them.

#33

I agree, easily manipulated is a better way of putting it.

#34

this^

accel or ramp tests are not the way to test peak power, steady state is
run car to ~7800 (a bit above power peak) under 1/2 load
increase load until engine slows down to power peak ~7600
hold for 10 sec and record for another 10

I’ve seen results for 2 car before/after clean comparisons, with only 1 cleaned
no statistical difference
maybe 1/2 mph trap, <2% power difference at most
one of the cars had the worse carbon I’ve ever seen, 70% occluded
Audi removed the heads to clean, new gaskets, plugs, etc.
still no difference

this is it, and was posted here by another

http://audirevolution.net/addons/albums/images/341858523.jpg

#35

Arthur - is here. Welcome.

#36

I heard Arthur was over here…This has totally made my day. Somebody keep debating CB or flow-rates of a sewage pump.

#37

I made sure to apologise to Arthur on RS246 and recognize that I now think he was more right than any of us on the effects of carbon buildup on the car’s performance. It’s kind of funny that he was trying to get us all to actually performance test our cars to see the effect of CB on RS4 performance (novel concept eh?) but we were all busy looking at dyno printouts and ignoring him.

As an RS4 owner, fortunately for me I am concerned with how my car performs, not with how the printer at the local dyno performs. If you live your life one dyno at a time like many/most RS4 owners on the forums do, the carbon buildup story can be a depressing one (especially if you let your car get dyno’d by the company you paid $900 to clean your car).

#38

Blake now too - today is a good day lol.

#39

would like to hear from B6scott too who joined recently…he’s a New York area RS4 owner who sold his RS4 and is working on a stage III B5 S4 that is currently stage III minus. He has been posting some dragstrip results over on AZ. Will be interesting to hear why he sold his RS4 though.

#40

if you have nothing to offer, insult
I know more about engines than any 5 people you know, which is 20 times as much as you
the EXACT same physics apply to a pump as an engine, but you wouldn’t know that
the primary difference being compressible vs. non fluids

I now certify engines for industrial use, dyno them (8 mode test), emissions, load, etc.
Cats, Deutz, cummins, etc.

there is no debate
deposits form
they do not cost any power
there may be a maintenance advantage in cleaning them, but no pwer advantage