Request for gents with a data logger:

[wellzieRS4]

Would having the wrong size tyres affect this test?

[Dom81]

so, if yours was reading that low, does that mean ALL were reading low?
if yours went from 310 to 390 (I don't believe either figure as absolute)
will the cars that made say 350 go to 420?
or the ones that made 370 go to 420+?

I was there both times too, running upper end of the stock cars first time, and slightly lower with shot tyres & old oil the second. Most who ran on both days (with no work in-between) saw very similar figures...

Apart from Scaghead, the other cars with unusually low readings first time round (Mac, Klauster, Oli etc from memory) all put the results to Audi and had relatively straightforward faults diagnosed & rectified.

[ArthurPE]

I think you're on to something, after 'turning it over' for a while I can't see an accurate reading on an inertia dyno for this set-up...

we know they work by measuring the time it takes to accelerate a known mass...no resistance or load, other than mass's intertia...
from F = ma or P = W/t = (f d)/t, obviously translated to rotational units
either T or P can be derived...

since our cars are 40:60, and when accelerated will put different T to each drum, the rear should spin faster than the front? the mech diff should be neutralized and remain at 40:60 since the front/rear surfaces are not interdependant, as they would be on a road...

the only other thing the car can 'do' when seeing a big difference in speed between the front & rear wheels is assume slip, and intervene and cut power/torque, to try to reestablish traction...
it would do so by adjusting timing, and this phenomena may be what we are seeing when we see timing being manipulated...

That'd be helpful Art.

I see that some dyno manufacturers claim they measure individual torque but I can't see how that would work unless you tell the machine the torque split in the first place?

Or else, like you say, things would spin at different rates...

They don't appear to so I'm thinking the diff is constantly trying to shift 10% of the torque to the front wheels to bring it back to 50:50?

I'm obviously missing something...

[scaghead]

I was there both times too, running upper end of the stock cars first time, and slightly lower with shot tyres & old oil the second. Most who ran on both days (with no work in-between) saw very similar figures...

Apart from Scaghead, the other cars with unusually low readings first time round (Mac, Klauster, Oli etc from memory) all put the results to Audi and had relatively straightforward faults diagnosed & rectified.[/quote] you are spot on fella and both mac and olis problems were air/vacuum related..

[S2tuner]

SR71: on our dyno, we have to manually select the torque split of the center diff in order for the dyno to measure correctly

[SR71]

Thanks for clearing that up Mihnea.

Good guess on my part?

[mac4RS]

dave you are spot on, we did this test after the rr day at paramount april 2009 one car dynoed 385 another 310..... in the real world on the road you guessed it, 310 was pulling away slightly in a 3rd gear drag

I can verify this, as I was behind both cars as they pulled away from me...

My problems were identified as 1) The pipe that feeds the flap to the air box was squashed - probably from when the car was built; 2) Flap in the air box seized & 3) Solenoid for the air auxillary flap was corroded with water in it.

And now the two same cars don't...

[Sims]

I can verify this, as I was behind both cars as they pulled away from me...

My problems were identified as 1) The pipe that feeds the flap to the air box was squashed - probably from when the car was built; 2) Flap in the air box seized & 3) Solenoid for the air auxillary flap was corroded with water in it.

And now the two same cars don't...

This issue has come up so many times - would a sticky be hepful.

That seems to have been a significant issue affecting RR results, and of course the 60:40 issue unless RR's can take that into account.

And someone mentioned tyres & oil age (would max oil level have a different result to oil at min level).

Is there a point to developing a standard checklist so all RS4's are tested with as few different aspects.

And finally, is there something about a B7 RS4 engine/electronics that thwarts attempts to get an accurate RR result.

[Sims]

Sims, I would suggest there are less variables in the 3k-8krpm test than on a dyno. Although cars do not use the same stretch of road and there is no account for incline this is offset against an r/r for slip and what I suggest is the biggest fault of r/r, torque vectoring and a r/r ability to measure that (particularly Dyno Dynamics roads) However what is constant is air flow rate and exhaust flow rate because you are travelling through air. r/r all rely on fans. I was one of Paramounts biggest critics because they used two small capacity fans and opened their fire exit to vent exhaust gas.

Compared to a number of other places I have visited the air flow and ventilation were not on a par. The rest of the variable are probably on a par. Yes there is human error in timing but again a r/r software's ability to translate its data.....

I also subscribe as someone else suggested that if you have delay error in judging start then usually there is delay error in stopping.

I take on board your comments about RR's, and that they are all not the same. At MRC, they have had a few cars recently and the results seem to make sense. I have suggested Priyan ought to bring his car there with the new engine so we can all better understand the benchmark. And if I have understood it correctly, MRC can adjust for the 60:40.

Would you mind posting results of all the RR's tests you have had carried out?

The 3k-8k test does not convince me - too many variables. Unless of course it could be conducted on the same stretch of road, same temp, same driver, same weight of car, tyre pressures etc etc.

[SR71]

Volcano has me grounded again....ah well...back to RS246.com...



Well the dyno, we now know, can cope with the 40:60 split...you just tell it what it is....

That Paramount day threw up some imponderables...although at least Mac & Oli got their cars sorted eventually as a result of it...which was a great result.

But me and Rob did test after test on the day that his car came back from MRC and the result was always the same....his car would just pull away from me...so it swings in roundabouts...

Our cars tested at 388hp and 390hp at SRR before the work.

There is always a reason for the anomalies, we just have to get to the bottom of it.

Thats the beauty of the Car Test software...you can control all the variables and vary them independently to see what effect they each have in isolation.

I might get a copy again...

[P_G]

Sims, I would suggest there are less variables in the 3k-8krpm test than on a dyno. Although cars do not use the same stretch of road and there is no account for incline this is offset against an r/r for slip and what I suggest is the biggest fault of r/r, torque vectoring and a r/r ability to measure that (particularly Dyno Dynamics roads) However what is constant is air flow rate and exhaust flow rate because you are travelling through air. r/r all rely on fans. I was one of Paramounts biggest critics because they used two small capacity fans and opened their fire exit to vent exhaust gas.

Compared to a number of other places I have visited the air flow and ventilation were not on a par. The rest of the variable are probably on a par. Yes there is human error in timing but again a r/r software's ability to translate its data.....

I also subscribe as someone else suggested that if you have delay error in judging start then usually there is delay error in stopping.

I take on board your comments about RR's, and that they are all not the same. At MRC, they have had a few cars recently and the results seem to make sense. I have suggested Priyan ought to bring his car there with the new engine so we can all better understand the benchmark. And if I have understood it correctly, MRC can adjust for the 60:40.

Would you mind posting results of all the RR's tests you have had carried out?

The 3k-8k test does not convince me - too many variables. Unless of course it could be conducted on the same stretch of road, same temp, same driver, same weight of car, tyre pressures etc etc.

I would do but from memory and having used so many over the years I'm not sure I have all or any of them now. The only one I have in my car file is the Dastek 396 bhp one. IIRC my Paramout one will be on that thread and there may be my original WRC Technologies on on here somewhere when I bought the car.

[Sims]

I would do but from memory and having used so many over the years I'm not sure I have all or any of them now. The only one I have in my car file is the Dastek 396 bhp one. IIRC my Paramout one will be on that thread and there may be my original WRC Technologies on on here somewhere when I bought the car.

OK. It just seems to me that your experience with RR's on RS4's is more than anyone's else's. And for people in the know, B7 RS4's & RR's are often mentioned in the same breath, followed by a splutter of carbon.

It would help if, at some stage, you could put together a summary of your learnings and findings.

[P_G]

I've not kept most of them because it became apparent that the figures did not lead to constructive analysis of my car's performance. I have used;

AMD x2 (Dyno Dynamics IIRC)
WRC Technologies x2 (Dyno Dynamics)
Well Lane Turbo Centre x1 (Dyno Dynamics)
Paramount x1 (Dyno Dynamics)
Motoscope x2 (Dastek)

All apart from Well Lane were as organised forum meets so went along for the banter and looking at other cars more then anything else, the runs were an inconsequential 'bonus'

FYI, WRC Technologies dyno'ed my car and then Chris showed how irrespective of shoot mode you could manually factor in losses to whatever % you wanted on WHP and CHP figures and the car could be seen to make the manufacturer figures.

IIRC some Dyno Dynamics model also have the same facility as MRC's road (by what S2Tuner said) to manually enter torque split but as suggested even if you do this and one axle detects slip then ESP 9.0 cuts power through the rev range to regain traction even though it is still accelerating under load and shifts torque even though you have it calculated at 60:40 and therefore may not be able to detect / correct / record quickly enough the actual power shift changes insitgated by the car.

[Sims]

FYI, WRC Technologies dyno'ed my car and then Chris showed how irrespective of shoot mode you could manually factor in losses to whatever % you wanted on WHP and CHP figures and the car could be seen to make the manufacturer figures.

I take that point on board, and it would be good if we could all use the same benchmark e.g. MRC or another for comparison purposes.

IIRC some Dyno Dynamics model also have the same facility as MRC's road (by what S2Tuner said) to manually enter torque split but as suggested even if you do this and one axle detects slip then ESP 9.0 cuts power through the rev range to regain traction even though it is still accelerating under load and shifts torque even though you have it calculated at 60:40 and therefore may not be able to detect / correct / record quickly enough the actual power shift changes insitgated by the car.

Agreed. Do you have contacts at Audi who can advise on how to circumvent that so that we have a level playing field?

[P_G]

Afraid not, they generally frown on people putting their car on rolling roads as it is. One time with my S4 one dealer even said it may invalidate my warranty running it on a r/r because it is 'abnormal driving conditions'.