Valves- carboning up

[ArthurPE]

Mr. Lewis's runs were in 108f temps...costs 0.3 sec...25+ HP
probably more due to timing...and lower fuel grade...
but regardless, he has deposits...and obvioulsy more than 370HP for a >4000 lb car to run times like that in 108f temps...
look at his best time, 8.4, in this temp...think about it...

fuel load, OA temp, passenger, etc. have a huge impact (a couple of 10th's)...cars on dynos that made 350 crank have run <8.5 sec...
cars that made 410+ on the dyno ran the same...do the math...

just because you don't like the results, doesn't mean they aren't meaningful...this is a FAR better indicator of relative power than a dyno...

this is the first car to run 9 sec (previous high was 8.5), but this is 108f temperature...

if a car ran 9 sec in 50f temps, you'ld have a point (or at least that car has a problem) the fact that the avg is <8.4 sec or so, tells me, no problem...

I have a feeling on why I've gotten few runs from the 'carbon/over rating camp', because their times are <8.4 sec...

you paid for 420 HP, and you got 420 HP...

I don't get this, it's got to be full of errors, but anyway, if not:

aka dk is doing it in 8 secs (7.9 in one run)
Matthew Lewis is doing it in a average of 8.7 (just under actually)

Arthur, if you say 25hp is 0.3 seconds, that's more than a 50hp difference between these two guys. Interestingly 'aka dk' is saying he has that boost at 5k.

Now I've seen cars running at 8.6 (I don't have a huge database like you) but surely the difference is showing that someone, even in your tests, can have a 50hp difference, and in each case you're saying the car is good. If I paid for 420hp and only got 370 I wouldn't be happy (assuming the difference isn't CARBON BUILDUP, mmmhahaha)

I'd put money on the difference is at the upper end of the rev range too.

Can someone time 3000-6000 and then 6000-8000?

[2manytoys]

You've missed the point, I'm talking about a car that has a difference of .03 seconds is down 25hp (that's your maths not mine). Forget about air temp at the moment, just talking time and power.

I don't care much for the results, as the variation is too big; a driver must look at rpms, press button, break speed limit, look for other cars, then press button again. It's just a test with too many errors.

Anyway, the main reason I posted was to question the 0.3 sec 25hp thing. You could be down 25hp by mistake, or up 25hp if you press the button 0.3 seconds too early.

[ArthurPE]

You've missed the point, I'm talking about a car that has a difference of .03 seconds is down 25hp (that's your maths not mine). Forget about air temp at the moment, just talking time and power.

I don't care much for the results, as the variation is too big; a driver must look at rpms, press button, break speed limit, look for other cars, then press button again. It's just a test with too many errors.

Anyway, the main reason I posted was to question the 0.3 sec 25hp thing. You could be down 25hp by mistake, or up 25hp if you press the button 0.3 seconds too early.

It's 0.3 sec...and OVER 25HP
this test has far less error than a dyno...many less 'variables'

I ran a statistical analysis on the numbers
adjusted for temp and weight (the reason I ask for that info)
all numbers come in at 8.2 to 8.4, very tight
low std dev and high confidence interval, over 30 cars iirc

as far as timing, and accuracy, actually the errors are offsetting...they timed the Olympics with a stop watch for 50 years...with 3 runs or more, the error will approach zero...once somebody gets the ang of it, it'll be spot on...

the facts are the facts, >30 cars, >100 runs, all ~8.3, vs a rating of 8.4...
or 8 sec flat for a car using all gears...

the cars are not 50 to 70 HP down like people are claiming...ALL times would be >9 sec if that were the case...even in low temps
and the only ones at 9 were these...and his avg was 8.7 in 108F, adjusted for temp, 8.4 w/poor fuel...

everyone will form their own opinion on the value of this data...
you don't believe it, OK, I don't believe deposits caused your car to dyno 260HP (wheels) or 330 or so crank...to each their own...

[ArthurPE]

interesting tidbit: I've been communicating with Audi, they have been very responsive
I asked thru normal web channels for the tranny/diff fluid spec, got a non-answer, see dealer...
then the prez (AoA) saw my request, had his personal secretary call and check...I told her it was less than useful...
1 hour later I got a call with all the data...very helpful
tranny 3.2 l (75W90, GL4 or GL5 fully synthetic, gearbox rated)
diff 0.9 l (75W90, GL5 fully synthetic)

I've heard they are testing cars that people think they are having issues with...
so far everyone has had another issue: vacuum leak, stuck flaps, etc., once fixed, the car is good...

they also test airflow and record it, then adjust for temp/atm P etc., and lay the curve over a curve of a car with a perfectly clean intake tract...
guess what? no significant difference...identical...they are taking these concerns seriously, in the States they are flying techs around to do this inspection and testing...

I plan on asking them if they have any info to share on a specific 'problem car' in Australia, lol

[2manytoys]

Just for the record, I may not have said this before, I'm sure some cars are fine. Some even with "acceptable" amounts of carbon. I'm also sure there are some, maybe less than the good ones I don't know, that are bad. The real bad ones are causing flow restriction and retarded timing (low power)

Anyway, Audi are replacing my PCV and then want to look at it again in 3000km to see what happens.

Also Audi in Australia are great. The dealer the car is in now is fantastic (Audi Central Coast). They are thinking the PCV may be the cause of the excessive buildup.

Fingers crossed it'll be fixed. I'll know on Monday afternoon.

PS: Agree, the most common problem would be vacuum/flaps. This is pretty easy to break, but also pretty easy to find. The symptoms are similar too.

[matthew.lewis2]

Sorry, I didn't mean it in a way that it had increased power; just as you say it should be down unless there is a remap along with that MRC filter but there is no mention of that?

To clarify, the car is running standard Audi software.

I did back to back dyno's before and after the decat and the dynos showed a peak improvement of approx 15-20whp (i cant remember without looking). I was going to have revised software installed (in July 2009), but due to a slight mixup on the day, i could not have it installed, and since then, the job market here in Dubai has been a bit shakey so i decided to keep my pennies in my pocket for a little longer. Maybe another 8 weeks and I will go and have the software installed.

My dyno's on a new engine and pre-decat install showed some really poor numbers http://www.rs246.com/index.php?name=PNp ... torder=asc , which makes me wonder about the dynos reliability or whether my car has 'loosened up' when reviewed against the 3k-8k test results I achieved yesterday.

[SR71]

My $0.02 but if airflow on "dirty" cars is the same as "clean" cars, in my opinion, the results are not being reported honestly. I reckon the difference is about ~2%.

See we have a play on words going here....because "significant" means different things to different people, especially in countries where taxation is based on quoted bhp.

Like I mentioned in another post if Neckarsulm both engine and chassis dyno R8's prior to leaving the factory, maybe they do the same to B7's.

If so, one would like to know what figures Audi get on the chassis dyno and, cognizant of that, depending on whether you're interested in wheel hp or flywheel hp, what the suggested losses are...

[HYFR]

matthew lewis, did you have the AC on ?

[matthew.lewis2]

matthew lewis, did you have the AC on ?

Good spot! I made a mental note when doing my runs, but forgot to jot that down with the timings.

Yes, I did have a/c on. I thought it better to have the driver alive and not suffering from heat-stroke when driving an "almost-supercar"

When the weather cools down (November time) and if this debate is still rumbling, i'll do a few more runs without a/c and with the cooler air.

[ArthurPE]

I don't believe Audi is lying, nor the folks who reported it to me...

2% difference is within the tolerance of measurment for airflow...and would only mean a 8 HP loss max...not 50 to 70HP
a 3000 mile air filter may cause a larger drop...or a few mb of atm pressure...or a few 100 ft of elevation....

it doesn't matter what Audi gets on a chassis dyno...
what matters is what the 3rd party, government mandated, independent testing got...and that is 420 HP...or they legally wouldn't be able to rate it as such...

engines aren't typically run on a dyno anymore for production testing...they are spun aby an electric motor and checked...

My $0.02 but if airflow on "dirty" cars is the same as "clean" cars, in my opinion, the results are not being reported honestly. I reckon the difference is about ~2%.

See we have a play on words going here....because "significant" means different things to different people, especially in countries where taxation is based on quoted bhp.

Like I mentioned in another post if Neckarsulm both engine and chassis dyno R8's prior to leaving the factory, maybe they do the same to B7's.

If so, one would like to know what figures Audi get on the chassis dyno and, cognizant of that, depending on whether you're interested in wheel hp or flywheel hp, what the suggested losses are...

[ArthurPE]

matthew lewis, did you have the AC on ?

Good spot! I made a mental note when doing my runs, but forgot to jot that down with the timings.

Yes, I did have a/c on. I thought it better to have the driver alive and not suffering from heat-stroke when driving an "almost-supercar"

When the weather cools down (November time) and if this debate is still rumbling, i'll do a few more runs without a/c and with the cooler air.

that makes your numbers all the more impressive...
temp 108f, stock w/decat (imo, may cost power) and AC on, avg 8.7 sec
vs rated of 8.4...when aducted for temp, 8.4 on the nose...

[Sims]

It may be boring to you Oscawhite but it helps.

Average is 8.68 which given the temperature is phenomenal. Given I can have a difference of 0.3 second average between 0 degree C and 13 degrees C I can't imagine how much the engine is retarded with 42 degree C temperatures.

P_G, I agree it can help if we compare apples to apples.

As an esteemed member of this forum, your view that rolling road results are unreliable has been noted. But it is a reference point with not so many variables.

However, the 3k to 8k test has so many variables - would it be helpful if you list all of them here and then the volunteers conduct the test using the same criteria. You could even suggest saloon drivers should have a full tank and avant drivers should only have 10 litres of fuel.

Further MRC Tuning have an open day on April 17/18th and will be conducting rolling road tests. Hopefully there will be some B7 RS4's there. It would be helpful if some (if not all) of those people conduct the 3k to 8k test immediately after the rolling road results. Perhaps with the use of a Vag-Com, and on the same stretch of road.

SR71 has suggested we establish what power RS4's recorded at the wheel (against flywheel at 420ps) when the cars left the factory.

That data, with the above, would be helpful to a better understanding of this contentious issue.

[ArthurPE]

the dyno has far more variables:
operator
set-up
manufacturer
tire pressure
calibration (of the machine itself and it's atm adjustment sensors)
ambient conditions
not to mention the inherent accuracy/repeatability of the machine, 5% at s...that's 20HP alone
if a dyno is an overall +/-10% I'd be surprised...>40HP error

3k to 8k
only the pushing of the button...we can safely assume anyones 'lag' time is consistent...if you start late, you stop late, ie, offsetting...after few runs people get the hang of it are very accurate...

if we factor in:
OA temp
load (fuel, passenger)
we remove 90% of the variables...

It may be boring to you Oscawhite but it helps.

Average is 8.68 which given the temperature is phenomenal. Given I can have a difference of 0.3 second average between 0 degree C and 13 degrees C I can't imagine how much the engine is retarded with 42 degree C temperatures.

P_G, I agree it can help if we compare apples to apples.

As an esteemed member of this forum, your view that rolling road results are unreliable has been noted. But it is a reference point with not so many variables.

However, the 3k to 8k test has so many variables - would it be helpful if you list all of them here and then the volunteers conduct the test using the same criteria. You could even suggest saloon drivers should have a full tank and avant drivers should only have 10 litres of fuel.

Further MRC Tuning have an open day on April 17/18th and will be conducting rolling road tests. Hopefully there will be some B7 RS4's there. It would be helpful if some (if not all) of those people conduct the 3k to 8k test immediately after the rolling road results. Perhaps with the use of a Vag-Com, and on the same stretch of road.

SR71 has suggested we establish what power RS4's recorded at the wheel (against flywheel at 420ps) when the cars left the factory.

That data, with the above, would be helpful to a better understanding of this contentious issue.

[ArthurPE]

what I find amusing is that if all the times were >9 sec (vs rated of 8.4), everyone would be using this as 'proof' of under-rating and deposit rated losses...on the other hand, since it doesn't, it's dismissed, lol

and that the most biased, accuse the most objective, of being the misguided ones...what a hoot...

[ArthurPE]

just added
aka dk
matthew lewis2
crispy
brooner

the database is getting huge...and very consistent...when adjusted for temp and wt, +/-10th centered at 8.2 or so...
I've used 70f and 1/2 tank as the baselinesl
I've also allowed an adjustment for a passenger and avants...

I am a bit concerned that folks are PM'ing data (please keep doing so if that's what you prefer) but imo they are doing so because:
1 they don't want embroiled in the 'controversy'
2 they don't want ridiculed, called a liar, foolish, etc., in the posts