B7 saloon dynoed - 308 hp at the wheels, 320 lb ft torque

[tartan_rob]

Did TG not test a Merc where one of their engineers came out to the car and had to do somehting else to get the ESP/TCS off? The switch only reduced it so far.

How about pulling the fuse? However, the ECU may recognise this and restrict the power accordingly.

[alex_123_fra]

Yeah we all know the limitations of the RR.

With respect to the B5's, I'd imagine the reason why everyone who dynos their B5 these days gets a relatively good result with regards to the stock quoted power is that RR operators now have a good idea of what the transmission losses really are.... Statistically, you dyno a couple of 100 cars and based on their output at the wheels you can work backwards from the quoted power to give an idea of the flywheel power.

However, when you've only dynoed a few B7's, you measure the power at the wheels, and then work backwards from the quoted power to build up an idea of the transmission losses, use that figure and unless you've thought about it, you're none the wiser.

The more of us who get our cars RR'ed, the better an idea of the true transmission losses we'll get.

Judging by what I've read, the spread of supposed losses is between 20-30% which is a ~40hp spread! Ridiculous.

Why bother?

Nevertheless, we know an owner who managed to get their car returned to Audi for "failing to deliver the quoted power" (sic).

Personally, I think the car is just about delivering the quoted power judging by the speeds it generates at the track and the times over the 1/4, but nevertheless it'd be nice to build up some solid information about why the car is failing to peform on the RR.

The C6 RS6 in the magazine article above was obviously unhappy on the RR, P_G has seen a S8 fail to deliver so I suspect inspite of switching the ESP off, there is still some electronic wizardry f**king with the results....

SR71, you are right that the spread of flywheel bhp figures is huge depending on the calculation used for transmission losses. It is a bit of a circular argument as most people don't actually understand what a dyno actually measures. This was the entire point of me putting up my graphs on this initially. I wanted to compare my results AT THE WHEELS with others who have dynoed their RS4s using a similar RR in similar conditions.

As I mentioned at the start of the thread, my car's 308 hp at the wheels is 405 hp at the flywheel using a 24% transmission loss (higher flywheel figures obviously if you use a higher transmission loss). The flywheel figure means precisely bugger all due to the problems with the transmission loss percentage calculation as most people have discovered. It is more useful if people compare at-the-wheel figures.

I don't believe that RS4s are underpowered at all. The timed performance of members' cars seems to suggest they produce 400+ bhp. The situation has arisen due to various inexperienced rolling road setups/operators who mislead customers into thinking they can actually give them an accurate flywheel bhp value for their car.

[S4INT]

I recently had a number of drag races in France with a friend in his Maserati Gransport (400bhp 4.2 V8, rear drive, paddle-shift, similar weight and bhp/ton). The results were that the cars were virtually identical, with the Maserati only pulling a few inches on each gear change. The Maser did slightly better in a top-gear roll-on, though I put this down to lower gearing on the Gransport. When you consider the drivetrain losses inherent with the quattro system, this leads me to believe that the full complement of horses are present and correct.

[APM]

Alex 123 fra; How was it £ to have your car dyno'd at surrey rr,as mines now done 83.5k and i'd like to know if the power
is + or -.

[chrissyr32]

Alex 123 fra; How was it £ to have your car dyno'd at surrey rr,as mines now done 83.5k and i'd like to know if the power
is + or -.

WOW!!! 83.5K!!! That must be the highest mileage B7 around surely!!

[PetrolDave]

WOW!!! 83.5K!!!

Is that miles or km?

[SR71]

Miles. Its JonP's old car isn't it?

[APM]

MILES,yes jonp's ex i've just had the KW v3's fitted,as the warranty was out for the Drc,I was qouted £5k ball park from Audi to
replace This was a verbal price,i think they should review their customer care policies.

[William_Blake]

RR tests can never be a true measure of the engine power & torque since you have to (gu)estimate the transmission losses.

The only real way to measure the power & torque of an engine is to take it out of the car and put it on an engine dyno - and that ain't a cheap or easy thing to do!

ask Audi what the losses are

i adore the RS4, we are thinking of buying one second hand but a few things are bugging me.. that is DRC problems and the fact that it doesn't produce 420 hp DIN.

in a straight line it has nothing on the new M3 which has the same weight and hp, only difference is RWD vs AWD

[Marcus-RS4]

MILES,yes jonp's ex i've just had the KW v3's fitted,as the warranty was out for the Drc,I was qouted £5k ball park from Audi to
replace This was a verbal price,i think they should review their customer care policies.

APM, did the DRC actually fail, or was it a choice to get rid beforehand? If it did fail, you must be the first one to have a failure beyond Warranty.. Did you send the letter to Audi, like the rest of us?

[William_Blake]

MILES,yes jonp's ex i've just had the KW v3's fitted,as the warranty was out for the Drc,I was qouted £5k ball park from Audi to
replace This was a verbal price,i think they should review their customer care policies.

5k for DRC??????

holy ****

[SR71]

ask Audi what the losses are

i adore the RS4, we are thinking of buying one second hand but a few things are bugging me.. that is DRC problems and the fact that it doesn't produce 420 hp DIN.

in a straight line it has nothing on the new M3 which has the same weight and hp, only difference is RWD vs AWD

Its only coz I'm off work stuck at home that I've got so much time at the moment to trawl the WWW site.....

If you adore the car, surely the decision is obvious?

My DRC hasn't failed and the fact that it might or might not generate 414hp on the RR hasn't stopped me enjoying the car.

No-one for a second thinks that if you pulled the V8 out and stuck it on a engine dyno it wouldn't develop 414bhp or are you willing to call Audi's bluff on this?

And whilst you might be of the opinion it can't keep up with the E92 M3, have you ever been on the road against one? Have you seen any M3 dyno plots? The ones I have seen show the same over-optimistic quotes on power for BMW too...i.e., the M3 fails to produce the stated power.

In another thread you claim E60 M5 is ~15 seconds 0-200, and the B7 ~16 seconds. The E92 M3 is not as quick as the M5, so if its quicker than the B7, its only half a second or thereabouts over a drag to 200! Insignificant on the road...all it takes is one car to be in the wrong gear at the start of the drag for that kind of advantage to be eliminated. (We tend not to believe the drag races you can find hosted on the BMW boards...for obvious reasons.)

AudiForums have a thread about a Greek test (@ 38C!) of the B7, E92 and ISF. ISF is quickest with nothing between the B7 and E92.

Still, most of us bought the B7 because of its all-round performance, dry or wet, its class leading interior and the fact it pre-dated the E92 by about 2 years!

If you like the car go for it.

If ~400hp isn't enough for you and you want a big hp car buy a modified B5 or C5 RS6.

[William_Blake]

very good point indeed

"(We tend not to believe the drag races you can find hosted on the BMW boards...for obvious reasons.) "


:p


DRC really is the only issue.. what if it breaks outside the warranty period?

[SR71]

As a collective we're trying to address this question at the moment.

If you read the DRC threads, you should get the gist of what is going on....

My DRC happens to be fine at the moment although I do have one weeping shock....

You will find the car is busy under very heavy braking...its a familiar observation. But you won't notice it unless you really are hauling the car down from significant speeds aggressively. There was some suggestion this might be a symptom of a car with a failing DRC system but I don't think so. Apparently SS+ cars are less susceptible to this dynamic.

Other minor issues with the car you can gain an idea of from the site...

[alex_123_fra]

Alex 123 fra; How was it £ to have your car dyno'd at surrey rr,as mines now done 83.5k and i'd like to know if the power
is + or -.

APM, it wasn't much only 40-50 quid. Very knowledgable they are as well.

With respect to Williams's point, that the M3 coupe (E92) is faster in a straight line than an RS4 (saloon), this is true. The Autocar test however found that the difference between the 2 cars was 0.3s on a sprint from 0-150mph. Hardly embarrassing for the RS4. The E92 M3 saloon is obviously heavier than the coupe version and I don't think it has the CF roof. That car is the natural competitor to the RS4 saloon and I have no doubt it is actually slower than the audi. In real world terms, there is probably nothing in it. The difference is that in the RS4 you won't be picking yourself up from a ditch or a side of a tree if you really push it in country roads. It really can be pushed at 10/10ths without staining your trousers.