Audi's reply to why our cars don't hit 414BHP

[toyneg]

Audi's response to me asking why our cars didn't hit the 414 figure in case anyone is interested

Subject:
Audi RS4 -

Dear Mr Toyne

Further to our telephone conversation of the 22 October regarding the BHP achieved by your Audi RS 4.

As we discussed, I have spoken to our Product Marketing Department on your behalf, who have advised that Audi measure the power
output at the flywheel as opposed to a Rolling road "dyno" test where the power output is measured at the wheels.

This will see a significant difference in measured output, as there will be losses through the transmission, wheels, tyres etc.
The manufacturers' tests are also conducted in very specific, laboratory conditions.
Factory specified power figures are very difficult to achieve for these vehicles using a rolling road dyno. Quoted factory
figures are achieved with the engine in a test cell and not fitted to the vehicle. They are tested to exact DIN standards that
ensure all of the ambient conditions are the same e.g. air temperature, air pressure, humidity, fuel octane, engine drag,
cooling performance etc. The problems that are encountered during rolling road dyno testing are:

• Air supply - being able to supply the demands of the engine.
• Ambient conditions - these obviously vary constantly.
• Cooling
• Drag calculations - corrected power calculations are made using the drag of the vehicle through the drive line during the
over-run phase. Some of these calculations can be distorted by poor dyno set-up and by the sheer road speed required to achieve
max power output rpm in 1 -1 gear ratio.

Thank you for taking the time to contact us, allowing me the opportunity to reply. If I can be of assistance with anything else,
please contact me on the details below.

Kind regards

[HYFR]

perfectly reasonable response

[MikeFish]

But doesn't explain why most other cars in their range hit the quoted figures on the same dyno.

[HYFR]

read in isolation, it is a reasonable response

in the context of the RS 4 dyno run vs. a n other then that is different.

[RIV]

I seem to remember at the rolling rd day the new rs4 was bang on the claimed power and the r8 v10, guess that puts things into perspective on what they have said ??

[MikeFish]

I seem to remember at the rolling rd day the new rs4 was bang on the claimed power and the r8 v10, guess that puts things into perspective on what they have said ??

Correct, I believe both the B8 and the R8 V10 made about the right numbers. And we all know a standard S4 puts out more on a dyno than the quoted manufacturer figures. So we know the Dynos CAN give a good indication of what the manufacturer says an engine is capable of producing.

And I also believe that Graham's question to them made reference to this. But they didn't answer it, they just gave us a narrative on how the figures are derived (albeit an insightful one).

At the end of the day we knew they weren't going to say anything new or admit there was a problem.

[Cecilthesausage]

So what is the realistic bhp figure....?

[MikeFish]

370 - 390 for a standard car that hasn't been carbon cleaned.

[PetrolDave]

370 - 390 for a standard car that hasn't been carbon cleaned.

Given that a B7 will now be between 5 and 7 years old that amounts to a drop of between 3 and 9 bhp (0.7% - 2%) per year - I think that's at least (and probably better than) average for ANY production car.

[esp_mm-270]

Its just that all VAG car figures have always been conservative except this one's bhp. The 0-60 is quicker than stated though

[PetrolDave]

Its just that all VAG car figures have always been conservative except this one's bhp. The 0-60 is quicker than stated though

So bhp is lower than stated, but the performance is better than stated... which really matters most? What the car actually DOES, or the bhp figure you can brag about in the pub? To me, it's what the car does (and how it does it makes me smile).

[scaghead]

Fair point dave..but people where getting those figures 4 years ago at paramount..I take rolling road figures as a guide only,and always thought it must be something to do with the rolling roads that could not measure the real cars output for whatever reason..but like others have said on the same day ,on the same rolling road ,with the same temperatures in the same environment other audis hit there stated output bang on...that is quite compelling evidence that they don't give you 414 standard...maybe there is some reason that dynos have never backed the stated output..
Funny enough mine was nearly bang on at amd(415).but to confuse things more it dynoed 435 a few months before..

[PetrolDave]

that is quite compelling evidence that they don't give you 414 standard

And my point is, who cares? The dyno numbers might not match the spec, but the actual performance is better than spec - so what actually matters? Numbers on a data sheet, or real performance?

In my book, it's real performance that matters - others will disagree, but that's fine.

[Les]

My car is seriously quick, and can show most cars how it's done, especially in the wet
How much power does it have? No clue and don't care because it certainly has shed loads.
It's time for this obsession with rolling road numbers to stop, jeez it's been 6 years now guys
I think we should accept Audi's explanation as provided by the OP(good job by the way) and move on

[RIV]

My car is seriously quick, and can show most cars how it's done, especially in the wet

I thought that about my car until I got it back from MRC, and now it is properly quick with an extra 100 BHP + as it was running crap before, but you get used to it, only until you get the figures from a dyno you realise something is wrong