Rolling Road on 24/11/2007

[W8PMC]

Interestingly the boys who own the RR have 911 turbos (did have rs4's) - They said that their 911's are quoted at 420hp, and that's also what their dyno states - if the 911's show all the beans on the dynos, then why don't our RS4's??? Their RS4's (march 2006) also showed between 370 - 380 hp - very similar to the resuts we got. VARSITY suggested that 2006 cars may have been more powerful, these results would seem to suggest otherwise.

Exactly.

If it is the 60/40 split thats causing it (as suggested) then how do they manage to get the claimed figures on the 911's, they have a 60/40 split too.

Also the cooling on the 911's is more complex as they have to be cooled front and rear so you would have thought out of the two cars the 911's would be the harder figure to obtain.

Is it not a different 4WD system on the Pork??

I thought (could be wrong & often am) the Porsche system although excellent, was a tad crude & dated in comparison to the more recent Audi Haldex & Torsen systems (excluding the 997 of course) & hence why dynos do not struggle in the same way.

At AmD back in the day in my RS6, they always appeared to get bang on outputs as i went through the various modification stages. Saying that, i've also learnt over the years that a dyno is only as good as it's set-up/ operator & can easily be set to output exactly what the customer wants/expects so the seat dyno is my judge & i know what my car can & can't keep up with & that it's certainly getting quicker with age/miles.

Not driven her for nearly 3 weeks, due to business trips to Vegas & Miami, so looking forward to a good blat down South tomorrow

[P_G]

IIRC some of the issues is also due to the ESP system on the cars. Earlier versions did not variate the power output as much, however ESP 9.0 which I believe the B7 RS4 has is constantly varying the power from front to back. Hence why if you have a look on the dyno plot the line is not linear, almost wavy in effect.

ESP 7.0 did this but did not cut power, like I say IIRC ESP 9.0 reduces power as well as power diversion.

[Andiroo]

IMHO all rolling road figures should be taken for what they are ie. the 'best' endeavor to calculate bhp ATW as a comparison for before/after mapping and modifcations ie. what percentage gain ATW do you get.

Again IMHO, backed up by facts (or lack of), and a lot of users on here, the bhp at the fly calulations are just 'finger in the air' jobbies - as in fact are some of the torque calculations. As several guys have mentioned the 'correction figure' can even be manipulated to suit as I have experienced.

Nobody, in particular from Audi, has ever sent a statement out, that I know of, which says "B5RS=X% Drivetrain loss, B7RS=Y% Drivetrain loss", so I really don't see the point of arguing on what FWHP results should be on a RR.

With my(B5RS), when I got told a map I was presented with was 550bhp Flywheel BHP , it actually showed 550bhp on the machine, with someone trying to tell me that the At The Wheels figure was 413.50. This was indicating some 30% drivetrain loss. Absolute pants as she felt a lot slower than that. After a few weeks of remapping 'on the road' with another mapper she felt loads faster (and noisier) and she was presented to G-Force who read her at approx 450bhp ATW and therefore (big finger in the air in 'their' words) 542bhp Fly. IMHO the guys at G-Force, with some serious machinery (GT1's), know what they are doing, and in their words 'a rolling road should only be used to 'try' and get a ATW's figure, and even then you cannot present true on the road parameters as the end result (FWBHP) can be manipulated as you see fit'. Half the time it's guess, some of you guys have posted "is it 16%, is it 20%, is it 22%?" -

On the Thorney RR day our forum friend Minhea suggests 30% drivetrain loss for calculating power on an S4 ie.BHP (which is the figure I worked on for my RS.

Surely the B7RS drivetrain cannot be that more efficient than the B5S4 and RS?

Only Audi probably know this IMHO so anything else therefore is pure speculation.

Don't know the answer to this one guys, but I don't think it will be RR comparisons unfortunately

Cheers,

Andiroo

[GrahamS4]

I don't think that is quite waht he said. Shame G-Force has changed hands. Only 0.1BHP @ the wheels difference between their dyno and Thorney's over 12 months apart though, not bad consistency.

[Andiroo]

I don't think that is quite waht he said. Shame G-Force has changed hands. Only 0.1BHP @ the wheels difference between their dyno and Thorney's over 12 months apart though, not bad consistency.

It is exactly what he said mate, and with the logic as above, who could disagree?

That is good consistency btw Graham. Just out of interest what factor of drivetrain loss did G-Force give you over Thorney's RR?

Cheers,

Andiroo

[sykotoy]

Havent read all the pages too many, what i do know is this , 25-30% drive train loss you guys are dreaming @16% so just over 300 bhp @ the wheels is what you are aiming for, btw my milltek increase after installation was 10kW @wheels better. Also dyno done in 4 th gear is the go.

[mrdeli]

Right come on then who's gonna volunteer to rip their engine out to settle this once and for all on the bench! ;@)

[Andiroo]

That's the only way to do it for 'real' mate

Cheers,

Andiroo

[simmo]

Right come on then who's gonna volunteer to rip their engine out to settle this once and for all on the bench! ;@)

Wonder if the buyer of this would be a willing victim..ahem donor for scientific purposes

[GrahamS4]

It is exactly what he said mate, and with the logic as above, who could disagree?

Now I hate to be picky, but as I remembered what Mihnea actually wrote was:

.....

Sorry for the disappointment, but I'm just not buying a 30% drivetrain loss for torque. Power, yes, but not torque. 198wHP is about right for a standard S4, especially judging by how lean the car runs standard, but 340ft/lbs (462Nm) is just wrong.

.....

This was a statement primarilly talking about torque and I interpretted the comment about 30% as to emphasise how it was not appropiete for torque, but in some circumstances perhaps for BHP. I dont see how you can read that as a quote of someone giving straight advice on B5 trans losses re BHP. If nothing else 265BHP (stock S4) is not a 30% loss to get 198wHP.

I think we are looking at ~22-25% losses typically looking at our figures from the day, which although maybe the machines equivalant of finger in the air, do seem to tally with molst people expectations.

Now until I saw my car run in Shoot_44 and be given fair trans losses I would have been talking power at he wheels only and agreeing. For me Paz's car was testament to the accuracy, if a stock car can read stock power, then what's the problem? (general question not you Andi).

That is good consistency btw Graham. Just out of interest what factor of drivetrain loss did G-Force give you over Thorney's RR?

Cheers,

Andiroo

The G-Force dyno, now run by DS Automotives, was run by the operator in SHOOT_6 mode. I now know that while this was correct for a 6 cylinder car, it was not even correct for a forced induction 6 cylinder car and it certainly wasn't right for any 4wd car. Therefore the transmission losses "calculated" were far too low.

The DS Automotives dyno in SHOOT_6 gave 249.2 BHp @ wheels and 302 BHP flywheel.

The Thorney dyno in Shoot_44 gave 249.1 @ wheels and 334 BHP flywheel.

I had an other car run at G-Force (when it was G-Force) and the power at wheels seemed good but the flywheel power seemed over, I cant find the plots but I do wonder if that was run in a suitable mode.

Even just talking about the one type of dyno (the SHOOT modes specific to DD dynos), I have noted B7 RS4s run in SHOOT_8, SHOOT44 and B5 S/RS4s run in SHOOT_6, SHOOT_6F and SHOOT_44. No wonder we see variations and people question numbers. As common with good machines I think the operators can let the equioment down!

Another problem where the numbers go all wrong is if people who have run on inertia style dynos whos flywheel figure is probably also roughly correct, but from what I have seen before have really high (low loss) wheel power figures compared to a DD HP (wheel) figure try and comparing the two. Or worse still adding ~22-25% to that and coming up with nonesense. Which of the wheel BHP measures is correct, who knows? This is where we see variation of opinion of losses being anything from 16% to 25%!

[alex_123_fra]

It is exactly what he said mate, and with the logic as above, who could disagree?

Now I hate to be picky, but as I remembered what Mihnea actually wrote was:

.....

Sorry for the disappointment, but I'm just not buying a 30% drivetrain loss for torque. Power, yes, but not torque. 198wHP is about right for a standard S4, especially judging by how lean the car runs standard, but 340ft/lbs (462Nm) is just wrong.

.....

This was a statement primarilly talking about torque and I interpretted the comment about 30% as to emphasise how it was not appropiete for torque, but in some circumstances perhaps for BHP. I dont see how you can read that as a quote of someone giving straight advice on B5 trans losses re BHP. If nothing else 265BHP (stock S4) is not a 30% loss to get 198wHP.

I think we are looking at ~22-25% losses typically looking at our figures from the day, which although maybe the machines equivalant of finger in the air, do seem to tally with molst people expectations.

Now until I saw my car run in Shoot_44 and be given fair trans losses I would have been talking power at he wheels only and agreeing. For me Paz's car was testament to the accuracy, if a stock car can read stock power, then what's the problem? (general question not you Andi).

That is good consistency btw Graham. Just out of interest what factor of drivetrain loss did G-Force give you over Thorney's RR?

Cheers,

Andiroo

The G-Force dyno, now run by DS Automotives, was run by the operator in SHOOT_6 mode. I now know that while this was correct for a 6 cylinder car, it was not even correct for a forced induction 6 cylinder car and it certainly wasn't right for any 4wd car. Therefore the transmission losses "calculated" were far too low.

The DS Automotives dyno in SHOOT_6 gave 249.2 BHp @ wheels and 302 BHP flywheel.

The Thorney dyno in Shoot_44 gave 249.1 @ wheels and 334 BHP flywheel.

I had an other car run at G-Force (when it was G-Force) and the power at wheels seemed good but the flywheel power seemed over, I cant find the plots but I do wonder if that was run in a suitable mode.

Even just talking about the one type of dyno (the SHOOT modes specific to DD dynos), I have noted B7 RS4s run in SHOOT_8, SHOOT44 and B5 S/RS4s run in SHOOT_6, SHOOT_6F and SHOOT_44. No wonder we see variations and people question numbers. As common with good machines I think the operators can let the equioment down!

Another problem where the numbers go all wrong is if people who have run on inertia style dynos whos flywheel figure is probably also roughly correct, but from what I have seen before have really high (low loss) wheel power figures compared to a DD HP (wheel) figure try and comparing the two. Or worse still adding ~22-25% to that and coming up with nonesense. Which of the wheel BHP measures is correct, who knows? This is where we see variation of opinion of losses being anything from 16% to 25%!

So graham, which mode would you recommend for a B7 RS4? Shoot_44 and shoot_8? Having mine done this afternoon on a DD dyno and would like to post some kind of roughly comparable results.

What is specific to these modes that makes them suitable to run the B7 RS4 on them. Have DD created RS4-specific modes for their dynos (to take into account the front/rear torque split)?

[W8PMC]

IMHO all rolling road figures should be taken for what they are ie. the 'best' endeavor to calculate bhp ATW as a comparison for before/after mapping and modifcations ie. what percentage gain ATW do you get.

Again IMHO, backed up by facts (or lack of), and a lot of users on here, the bhp at the fly calulations are just 'finger in the air' jobbies - as in fact are some of the torque calculations. As several guys have mentioned the 'correction figure' can even be manipulated to suit as I have experienced.

Nobody, in particular from Audi, has ever sent a statement out, that I know of, which says "B5RS=X% Drivetrain loss, B7RS=Y% Drivetrain loss", so I really don't see the point of arguing on what FWHP results should be on a RR.

With my(B5RS), when I got told a map I was presented with was 550bhp Flywheel BHP , it actually showed 550bhp on the machine, with someone trying to tell me that the At The Wheels figure was 413.50. This was indicating some 30% drivetrain loss. Absolute pants as she felt a lot slower than that. After a few weeks of remapping 'on the road' with another mapper she felt loads faster (and noisier) and she was presented to G-Force who read her at approx 450bhp ATW and therefore (big finger in the air in 'their' words) 542bhp Fly. IMHO the guys at G-Force, with some serious machinery (GT1's), know what they are doing, and in their words 'a rolling road should only be used to 'try' and get a ATW's figure, and even then you cannot present true on the road parameters as the end result (FWBHP) can be manipulated as you see fit'. Half the time it's guess, some of you guys have posted "is it 16%, is it 20%, is it 22%?" -

On the Thorney RR day our forum friend Minhea suggests 30% drivetrain loss for calculating power on an S4 ie.BHP (which is the figure I worked on for my RS.

Surely the B7RS drivetrain cannot be that more efficient than the B5S4 and RS?

Only Audi probably know this IMHO so anything else therefore is pure speculation.

Don't know the answer to this one guys, but I don't think it will be RR comparisons unfortunately

Cheers,

Andiroo

What he said

Dyno for pissing contests, seat dyno for real world & track for head to head fun.

[GrahamS4]

So graham, which mode would you recommend for a B7 RS4? Shoot_44 and shoot_8? Having mine done this afternoon on a DD dyno and would like to post some kind of roughly comparable results.

What is specific to these modes that makes them suitable to run the B7 RS4 on them. Have DD created RS4-specific modes for their dynos (to take into account the front/rear torque split)?

I am not really in a position to recommend , you must understand this is information I have gathered through an interest. You would hope those operating the machine would be suitably trained. I certainly am not.

I would say SHOOT_44 for sure. I believe the different modes are different roller rates (whatever that helps with) but they also have a big variation over what the S_HP reading is (engine BHP). The HP (wheels)reading on the graph should be consistent regardless I *THINK*.

SHOOT_44 is for 4wd cars full stop is the info I have had.

[GrahamS4]

What he said

Dyno for pissing contests, seat dyno for real world & track for head to head fun.

Ear dyno is good too. Make a car louder is always feels quicker.

[P_G]

I concur. My personal usage of Dyno's is to make sure the car is operating as it should, not to go down the pub wth the figures for bragging rights. Plus you can to a certain degree tell if your car isn't running as it should, dyno is just to back this up.

I feel the my RS isn't as quick as it should be given my S4 experience OEM and modified, hence ging to WRC next week.