RS4 B7 Stated Power claim of 420ps MKII

[Sims]

I never alluded it was Arthur Sims, you assumed..... incorrectly

Arthur has not PM'ed me on this subject but we have spoken outside this forum about other RS4 related subjects with no intent other than that.

That's all clear now, see earlier posts

[ArthurPE]

I have not seen the open posts directed at you, or others specifically. And that seems inconsistent to me.

However, I think that is cleared up now that there will be no insulting language and use of words like lier,loser,whiner, choad etc etc ever again.

you've read every post? you've only been here 2 months...

that is a perfect example of the passive agressive, indirect BS they were alluding to, lol

[Sims]

I have not seen the open posts directed at you, or others specifically. And that seems inconsistent to me.

However, I think that is cleared up now that there will be no insulting language and use of words like lier,loser,whiner, choad etc etc ever again.

you've read every post? you've only been here 2 months...

that is a perfect example of the passive agressive, indirect BS they were alluding to, lol

so do direct me to the thread, and I see the name calling has started again.

[ArthurPE]

so do direct me to the thread, and I see the name calling has started again.

[Sims]

Personal opinion, don't start another thread up on the same subject John because it will just degrade into the same name calling crap .

P_G?

[Sims]

so do direct me to the thread, and I see the name calling has started again.

So do tell where the thread is?

[ArthurPE]

P_G?

[ArthurPE]

So do tell where the thread is?

[P_G]

Personal opinion, don't start another thread up on the same subject John because it will just degrade into the same name calling crap .

P_G?

The one that got locked for which John started another on the same subject?

[northernpar]

Sims, the main difference here is that most folks are debating a point whereas you are continually trying to prove a point. There is a subtle but distinct difference between the two. I've no doubt that your intent is to be an active and positive contributor to the forum but from time to time there will be differences of opinion, particularly where uncertainty over the issue still remains. When this happens usually the debate will be centred around objective fact with some subjective opinion but hopefully will be a stimulating and educational experience for those who post. However, objective fact will always have more weight than subjective opinion in a debate.

Now, I have remained relatively silent on this subject other than to echo others comments which are enjoy the car and worry less about things that are currently unproven and quite frankly out with our control. However, I have a background in gas turbine design specifically on low emission fuel control systems so have a good appreciation on internal combustion technology and fuel management which lends itself well to certain issues but there are other members who are imminently more qualified/experienced to comment on these matters with respect to automotive technology.

From what I can see thsi all boils down to determining the reason for certain cars appearing down on the stated power. A number of members have pointed out that the use of rolling roads as a defintive test of car power is potentially frought with error due to the amount of variables/correction that is required and that empirical road tests (3k-8k times) could be a more reliable way of determining a change. However this is also not an exact science again due mainly to the variables involved. In summary both are prone to error and are probably more use as a baseline from which to measure deviation from.

Having tested engines (albeit) gas turbines in a test cell environment I understand fully the required controls in place to certify power and can state cetgorically that these are not mirrored in the real application (if they were the product would be significantly more expensive). Ambient temperature and pressure, mass air flow, specific humidity, compression pressure and temperature, fuel flow and LHV, exhaust temperatures and products are all measured or calculated/infered to a high degree of accuracy along with the positioning of any variable geometry that will affect air mass flow to ensure that the engine meets its stated power claims at ISO conditions. So in this respect I have no doubt that AG have gone through this process many times and am confident that the engine can put out its stated power.

Now let's consider the real application of the engine in it's surrounding environment. There will be natural wear and contamination through usage will which be heavily dependant on usage and environment. Air quality, fuel quality, driving style will all factor into this somehow although I suspect that this will produce some variance between engines I am not convinced it is the main cause where people are experiencing genuine power losses. Sure, the carboning up will have some effect on mass air flow and possibly combustion efficiency but probably not enough to cause a 20-30% loss in real power and the cleaning of the intake manifold will undoubtedly improve these area. I would not dispute this either but probably not enough to warrant the power gains of 20-30%.

So assuming that the engine is mechanically sound and that carbon deposits will have an effect but not one that will cause significant loss of power we must consider the fuel system as a whole. What I have found the most interesting with this engine is the variable geometry installed. It has been stated that AG always had a problem getting air through this engine to make the power. Not sure why this is but perhaps the compact design and operation have something to do with it and in order to find a reliable and acceptable balance the variable geometry of the power flap and intake vanes were designed in. Both have the potential to significantly affect power by reducing air mass flow and both have fairly rudimentary position control which will introduce error in position that wouldn't necessarily be detected by the engine management system as a fault. To give you the example on gas turbines the inlet guide vanes had position feedback and on more modern engines a closed loop control on the positioner so that the actual position could be guaranteed within an acceptable tolerance. There were other reasons for this but what it did do is eliminate error in the air mass flow. Now say we have two cars who's operation of power flap or inlet vanes or both are different due to wear/sticking of the mechanisms then you would undoubtedly see a difference in power. There are a number of examples where this has happended to members where a leak in the vacuum system has compromised control of these items and at least one where the inlet vanes were sticking where when cured the power had returned. It's also not beyong the realms of possibility that when an intake manifold has been removed for cleaning that during this process the underlying cause has been fixed such as the inlet vanes or a vacuum leak which when the manifold is put back on and the power returned could give the impression that the carbon build-up has been the main cause. Now, because none of this has happended in a controlled environment this will remain a theory but a fairly plausible theory at that.

Taking aside the potential effects of the variable geometry we will also have to content with errors in other parts of the engine management system (MAF, lamda, throttle body etc) which will have fairly generous tolerance so could be significantly different between cars. The theory is that the engine management will correct for this so will have some part to play in lessening any effect however if you are unlucky enough to have all the tolerance of error in the wrong direction then this too could have a significant affect on realised power.

So, taking all of the above into account and looking at it from a fuel management perspective I believe (and this is my opinion only) that while we focus on carbon deposits and continue to debate the virtue of rolling roads we may be distrcting ourselves from determing the real causes and potential fixes for the dreaded loss of power. The unfortunate thing is that even if we had someone with a car which was down on power who was willing to go through a detailed process to diagnose exactly what the causes were there are simply too many variables to contend with to get definitive answers outside of a test cell environment. As has been stated before the only way in order to prove what the issues are would be to take the engine into a test environment which would involve substantial cost in creating the required conditions and measurement parameters which, let's face it, unless AG elect to do it is never going to happen.

Now, whilst I enjoy these debates and am interested in the issue (perhaps background has something to do with this) I can't/won't overly concern myself with something that I have very little influence over. That's not to say I will choose to be ignorant of the issue as I will undoubtedly start to have a look at the engine/fuel management system over time in order to attempt to understand/elimate these potential sources of error (will probably elect to do this at the same time as fitting Milltek/GruppeM intake) but until that time I'll enjoy what I have.

Apologies for the long and rambling post (felt I had to get my opinion out there) and well done to those who managed to read it to the end.

[Sims]

Apologies for the long and rambling post (felt I had to get my opinion out there) and well done to those who managed to read it to the end.

Good read

[HYFR]

excellent post...

my car too has suffered 'flaps' problems (im a layman) and was noticably faster after 5k rpm when fixed

[Sims]

Another good read was what SR71 said, on the original thread.

I'm sorry, but I'm inclined to agree with sims.

Audi should just step up to the plate and comment on the matter.

When a S2/RS2/8L S3/8P S3/B5 S4/B5 RS4/S5/D2 S8/V10 R8/TT/TTS/TTRS (amongst others) all make the claimed numbers on the dyno, if a B7 RS4 doesn't, it ain't because the dyno operator is prejudiced against B7 RS4 owners! So IMHO, the "can't trust a dyno" argument is a red-herring.

Mihnea probably has more experience with the Audi marque than anyone? And like he says, even if he does work for a tuning shop, why would he care if a B7 didn't make the numbers? He is just calling it the way he sees it surely?

I spend my life in an industry looking for the last fraction of a percent in performance. Its worth millions of dollars a year.

I do care about the last few percent, 1/10 in the 1/4, few degrees of ignition advance etc etc.

Thats why I bought a RS4 not a Trabant.

I actually have a letter from the CEO of Audi UK opening a case file on the matter and referring it to their Technical Department. Its probably still open? I was feeding back data on my oil samples to them as well but as I've got rid of the car, its a little hard for me to pursue any further and I'm not inclined to do so.

That said, I will steer away from DI cars until such time as I personally feel the paradigm has a degree of longevity in the performance sector.

The standard of debate 2 years ago on this WWW site was good, long before most of the contributors on this thread had even joined.

My own $0.02.


Right now, my car does not have a power issue. But I read about many others who have. I will not ignore that. Having said that do read my very 1st post on the original thread. & this issue is being raised people all over the world. Those who are attempting to suppress it are doing Audi no favours. Allow the discussion to continue and data to flow in. Perhaps a letter to Audi from the Forums requesting clarification will sort this issue, rarher than individual representations. It is naive to believe Audi are unaware of this issue having bought a car back, having changed an engine. And someone on RS6.com did say the problem will not affect the RS5. What does that tell you?

I did not have to pay for the very expensive (more than Porsche & BMW) extended warranty, and yet I feel that issue needs to be raised. BMW jacked up thier warranty costs on 2006, but backtracked in 2007 because of strong representations from forums.


The DRC issue got resolved, but only for 75k miles. So if you car has done 74k miles and you get new dampers (as some are getting), what happens after you cross 75k miles? It is a question for long term ownership of a car. Should it have had a permanent fix? VdT. Did BMW's have Vanos & Porsche have RMS issues? AFAIK the early RS5's will not have DRC, anyone here know why?

As Scaghead said in another thread, our end goal is the same. There are a lot of well meaning people here, but it's also new blood that is required as the catalyst to move forward.

I am very happy with the RS4 package, and the issues mentioned are capable of being resolved, and will enhance residuals.

[victor2vt]

Right everybody, you've all had your say, NOW LETS MOVE ON !!!!

[P_G]

Well done northernpar, esopecially as you have technically managed to put into context a lot of my thoughts and theories on what the issue of power loss could be attrributable to beyond carbonisation and is in all probablility the root cause after seeing past the distraction of carbonisation.