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

[alex_123_fra]

Hi Alex,

Your car gave almost exactly the same power as mine when it was standard:

Same shoot-out mode etc.

Still yet to see a standard one give the full 414 though....

Hi Saint. Again, I'm not really too concerned about the flywheel figures as that is pure guesswork depending on what percentage transmission losses you want to use. As ARSEY4 says, had the dyno used a 25% transmission loss (instead of 22%) in the calculation, the flywheel figure quoted would be 411bhp. Had it used 30%, the flywheel figure would be 439bhp.

I see the power at the wheels figure as being more valuable and as it is, I'm fairly pleased with it as it ties in with what I expected of the car. I certainly don't believe one can use these graphs as evidence of this car being underpowered. There are too many variables involved. If your car produced about the same, I'd say that is about right.

I dont really understand this rr stuff but I pressume that you are saying that the car looses aprox 22% through the wheels therefor in order to get to a quoted BHP of 414 the car should make 323 at the wheels.
At 25% loss ist should be 311
At 30% loss it should be 290
The bit Im not sure about is that presumably when you do a 4 wheel drive car how does the machine know what the different splits are ie; RS4 is 60:40 split and rear bias.
Are our cars variable in this split ala haldex system or are they fixed at 60:40?
There must be so many variables in the calcs.

ARSEY4, you're absolutely right about the transmission losses. As far as what the dyno dynamics dyno does to infer the wheel horsepower, I'm not entirely sure. I know that the operator had to choose a set of modes prior to running, such as engine capacity, drivetrain, etc. It gave options such as AWD, 4WD - centre diff etc etc. and he picked the most approriate one.

I believe the 60:40 split is fixed but if the TC/ESP is on, I was under the impression it could transfer more power to each wheel with more traction. Hence, to avoid spurious readings, we switched ESP/TC completely off (indicator light on dash solidly illuminated). As you say, there are many variables in the calculations which I couldn't even begin to comprehend, hence I'd take any dyno readings with a pinch of salt. They are inferences at best and figures are deduced in a very indirect manner.

Alex

[ARSEY4]

Thanks alex.

[P_G]

Alex, what temperature was your car running at when you did these runs?

Both engine temp and air intake temp will affect the readins too. I will try and simulate the same on my runs as much as I can to maintain some consistency since I am also using a dyno dynamics road.

[alex_123_fra]

Alex, what temperature was your car running at when you did these runs?

Both engine temp and air intake temp will affect the readins too. I will try and simulate the same on my runs as much as I can to maintain some consistency since I am also using a dyno dynamics road.

Hi P_G, unfortunately, I didn't plug in VAG-COM so I didn't log intake temps. I'd say the car was dynoed at a temperature of around 15-18 C degrees. Outside temp was 12-13 C when I arrived (from memory), but obviously the runs were done inside where it was warmer (despite the enormous fan that was being used to cool the car).

From what I remember, the WRC dyno has superb airflow capabilities as they are able to partially shut the dyno roof rollers and the garage roof rollers to create a huge draft that seems to be amplified by the fans. It is a good setup.

[P_G]

Well, as promised I had my run at WRC today and the results aren't the saem as yours Alex. My RS actually performed better on Shoot_8 rather than Shoot_44 because WRC's Shoot_8 program is designed for 4WD V8's
Shoot_8


and Shoot_44



Which by DD extrapolation would have brought up



Interesting because Shoot_8 had higher roller loss but more power. And the runs were done in 3rd and 4th gear and the loading up to 3000rpm in third was terrible, 4th produced better results so long you didn't bounce off the r/r speed limiter which was tricky because 8000 rpm equated to 127 mph and the r/r limit was 128mph!

So looking at Shoot_8 (the first graph) and having phoned someone at Audi UK who said that through a r/r there could be up to 31% transmission loss would give a figure from my results of 414.3bhp and 322 ft.lbs as seen on the graph.

I also asked Chris about the other RS4's he had dyno'ed and none have produced the quoted figures. And when remapped they have seen improvements from 10bhp in MY07 cars up to 50bhp on early RS's, there is not set improvement.

So we are no further forward really, but I'm happy with the figures as it is about what I thought and it's still a great car. Had fun trouncing a Civic Type R on the way their along the A43 this morning!

[alex_123_fra]

Interesting results P_G, thanks for posting. I may have to try the WRC dyno for comparative reasons and will do shoot_44 and shoot_8 runs to see the differences in my car.

I personally don't believe that the RS4 transmission loses 31% from flywheel to tarmac/RR...more in the 24-25% region but that is just personal opinion. It is in audi's interests to quote higher transmission losses so that the flywheel figures on dynoed cars appear more impressive.

In order to get some comparative data on how RS4s dyno on different modes and different RRs, it would be useful for me to try WRC's dyno and you to maybe try Surrey RR if you wanted. They both have fairly new DD dynos. It would then be useful to compare 3rd and 4th gear as well as shoot_8 and shoot_44 figures. This would give an idea of inter and intra-dyno variation and a comparison of what different cars might achieve.

Also, in my view, it isn't worth using flywheel bhp figures for comparisons as the fudge factor (transmission loss calculation) varies depending on what one wants to show. For example, my shoot_44 run of 308 HP at the wheels equates to 440bhp at the flywheel using a 31% transmission loss calculation. That is plainly ridiculous as I don't believe my car produces 440bhp (although it is very quick). At the wheel figures are going to be as reliable and comparable as it gets.

So far the results highlight to me that RS4s dyno very differently in different modes, different RRs run by different operators in different conditions. I think the whole "underpowered" RS4 argument is untrue and is unprovable unless engines are stripped and engine-dynoed (as a lot of us have been saying for a while). The odd cars maybe down on the quoted figures but I don't believe there is a generalised problem.

If I were audi, I wouldn't be at all worried about defending their stock-quoted figures in court against anyone who says they are untrue based on dyno results. It would just be too easy for them to win. They will settle the odd case out of court as they probably can't be arsed with the hassle and don't want to put loyal audi fans off their future products.

[P_G]

I have heard of one person who'd been an Audi customer for some 10 years who got his money back from Audi having bought an RS and it was dyno'ed and the customer took it back saying it wasn't what it should have been in terms of power and the car.

And if they were producing 414bhp in testing and development, why so many post distribution firmware updates?

Like said I think at r/r days at one place, perhaps WRC, would be a good way of truly testing these cars unders ismilar conditions.

BTW Alan doesn't co-own it any more, he and Chris unfortunately had a 'parting of the ways'.

[alex_123_fra]

I have heard of one person who'd been an Audi customer for some 10 years who got his money back from Audi having bought an RS and it was dyno'ed and the customer took it back saying it wasn't what it should have been in terms of power and the car.

And if they were producing 414bhp in testing and development, why so many post distribution firmware updates?

Like said I think at r/r days at one place, perhaps WRC, would be a good way of truly testing these cars unders ismilar conditions.

BTW Alan doesn't co-own it any more, he and Chris unfortunately had a 'parting of the ways'.

Yes it may be the same person whom I'm thinking about who posts on here. I respect him for what he did and his car may well have been underpowered, but I don't see proof anywhere of a generalised problem. There are plenty of us who have had more than expected at the wheel figures on dynos but of course people usually tend to remember the bad ones.

Re: firmware updates, I am not sure how many there are...I thought there was only one and its purpose was to smooth out the cold-running issues rather than anything else . Is this uncommon from manufacturers these days?

Yes I heard about Alan. Funny he had posted on the mistubishi lancer register saying that WRC was ceasing all services and closing down. Glad Chris was able to rescue it and keep going though, great chap.

[Andiroo]

So far the results highlight to me that RS4s dyno very differently in different modes, different RRs run by different operators in different conditions. I think the whole "underpowered" RS4 argument is untrue and is unprovable unless engines are stripped and engine-dynoed (as a lot of us have been saying for a while). The odd cars maybe down on the quoted figures but I don't believe there is a generalised problem.

If I were audi, I wouldn't be at all worried about defending their stock-quoted figures in court against anyone who says they are untrue based on dyno results. It would just be too easy for them to win. They will settle the odd case out of court as they probably can't be arsed with the hassle and don't want to put loyal audi fans off their future products.

Couldn't agree more with your logic alex

I'm still stumped on the 31% trans loss, several sources quoted me in the region of 30% for my B5 back in 2002, albeit most were RR operators trying to make me a happy guy although some were Audi Quattro Techs. Have to say not none of my investigations showed a perceived loss (you have to laugh) of less than 26% with some at 33%:shock: The B5 box surely isn't that much more efficient than the B7 box for it to be say 22%?

As you say mate, it's all a 'black art' at the moment (not even an art IMHO), but the crucial question for me that most pepes try to avoid (apart from you my friend and a few others) is WHAT IS THE ACTUAL TRANSMISSION LOSS? (sorry for shouting )

Until we know this we should all compare WHP full stop be it B5 B7 etc etc. This is why the Skyline R32/33 guys stopped talking FWHP from RR's 5 years ago

Cheers,

Andiroo

[mixja]

Anybody used a hub dyno? They will read higher but at least you remove the vagaries of tyre pressures, how tight the ropes are, etc, etc...

I'm getting mine dyno'ed stock on a hub dyno tomorrow - should be interesting, although it has only done 1000kms...

[P_G]

I remember Jon dyno'ing his D3 S8 and IIRC Audi had advised him that the car could detect it was on a r/r and would turn down the wick and as a result his dyno was some 100 bhp down on what it should have been.

The things people say.

As for the B7 RS4s vs B5's, I do have a suspicion it is more to do with the ESP system more than anything else. I'm pretty sure ESP 9.0 is still on albeit you are told you can switch it off on the B7 and that is what restricts some of the power, not just transmission.

Alex, I should have been more specific and say that Chris now runs Weltmeister, WRC name has officially diappeared but Weltmeister was up and running as a side company when Chris and Alan were working together.

[SR71]

In principle I agree with the debate but I also agree with Anton who in a previous thread said its ludicrous to suggest you lose 25% of your cars power as a result of transmission losses.

That would equate to ~100hp and your transmission would be on fire for that to be the case.

What we all really need is for Audi to commit and say what we should all see at the wheels.

They've presumably got a host of test cars so all they need to do is shove them on their dyno and let us know the average/what we can expect. Whats the difficulty with that Mr Audi?

[alex_123_fra]

So far the results highlight to me that RS4s dyno very differently in different modes, different RRs run by different operators in different conditions. I think the whole "underpowered" RS4 argument is untrue and is unprovable unless engines are stripped and engine-dynoed (as a lot of us have been saying for a while). The odd cars maybe down on the quoted figures but I don't believe there is a generalised problem.

If I were audi, I wouldn't be at all worried about defending their stock-quoted figures in court against anyone who says they are untrue based on dyno results. It would just be too easy for them to win. They will settle the odd case out of court as they probably can't be arsed with the hassle and don't want to put loyal audi fans off their future products.

Couldn't agree more with your logic alex

I'm still stumped on the 31% trans loss, several sources quoted me in the region of 30% for my B5 back in 2002, albeit most were RR operators trying to make me a happy guy although some were Audi Quattro Techs. Have to say not none of my investigations showed a perceived loss (you have to laugh) of less than 26% with some at 33%:shock: The B5 box surely isn't that much more efficient than the B7 box for it to be say 22%?

As you say mate, it's all a 'black art' at the moment (not even an art IMHO), but the crucial question for me that most pepes try to avoid (apart from you my friend and a few others) is WHAT IS THE ACTUAL TRANSMISSION LOSS? (sorry for shouting )

Until we know this we should all compare WHP full stop be it B5 B7 etc etc. This is why the Skyline R32/33 guys stopped talking FWHP from RR's 5 years ago

Cheers,

Andiroo

I completely agree Andiroo. I guess the only way to determine an accurate figure for B7, B5 etc. transmission losses would be to strip a sample of standard random B5s and B7s. Engine dyno them and then, in identical conditions, put them on a normal rolling road (e.g. dyno dynamics) or a hub dyno to get power/torque figures at the wheels in the same cars. Then you could average out the transmission losses in each model. Not sure who would volunteer for such a mammoth task...not to mention the expense.

SR71, in an ideal world, it would be nice for audi to put a few standard cars on a "normal" dyno and give us figures at the wheels. I don't think they would ever oblige though as they will say they already use the "gold standard" in their extensive engine testing (i.e. engine dynamometers) and if there are any figures to actually believe out there...engine dyno figures that manufacturers use are the ones.

What we need is an accurate way for the average joe to work out if their car is underpowered or not. For 4WD cars, I think dynos (not engine dynos) can only go part of the way toward doing this, but their figures aren't really proof of anything as evidenced by all the discussions in this and many other fora. Maybe combining dyno results with set timed runs where you can indirectly calculate the power to weight ratio of the vehicle based on weight, timing of run, distance and aerodynamic profile

[mixja]

Just got back from the dyno, only made 308HP at the hubs @ 6800 RPM - power dropped off considerably after this...

Found that we had to run the car with ESP off but traction control on - turning everything off, one of the front wheels wouldn't get any power...???

[P_G]

So that's approximately a 26% transmission loss, so not much different to anyone else.

I still find it curious that virtually all previous Audi S and RS models when dyno'ed in OEM state would prioduce figures spot on the manufacturers stated figures but B7 RS4's don't.