Dyno Bullshit!!

[SR71]

The Audi RS4 publicity I have lists the kerb weight of the Avant at 1710kg according to Directive 92/21/EEC

http://eur-lex.europa.eu/LexUriServ/Lex ... 021:EN:NOT

Which doesn't seem particularly helpful on first reading...

[Gazzer68]

I got my weight from the audi website, they list the saloon as 1650, avant 1845

[Oli]

I thought the kerb weight was 1710kg, Im sure it isn't 200kgs heavier than the saloon......

[ArthurPE]

The Audi RS4 publicity I have lists the kerb weight of the Avant at 1710kg according to Directive 92/21/EEC

http://eur-lex.europa.eu/LexUriServ/Lex ... 021:EN:NOT

Which doesn't seem particularly helpful on first reading...

in my experience, all mfgs are way off when quoting weights...

the EC std includes, iirc, 75 kg driver and 10 kg of stuff..90% fuel...

the only way to know, is to weigh

the mfgs weights don't include options: sunroof, nav, etc.

[W8PMC]

I honestly don't thik that the stock B7 performs like a 414bhp car though in the real world. I've owned a B7 and driven a Cab for months and it felt down on horses. The stock B5 at 380 felt right and my remapped B5 will embarrass a stock B7.

I ain't in here to troll,. 'm relating to whaty W8PMC said that it's all about how they drive in the real world and for me it's a bit of a let down. The fact that these cars don't make the quoted manufacturers claimed BHP output does not surprise me in the sligtest.

I've been in Jims car and that now feels how mine should have been from Audi so something is amiss.

I totally disagree, my car feels full of it's claimed 420+BHP. Your car may be a bit or alot slower than mine, infact yours is a cab so it will be slower as it's around 200KG heavier than mine.

Without raising the Cab/Avant/Saloon debate, the saloon is the lightest of the 3 bodies by a fair margin, with the Avant next & Cab the heaviest. They all have the same Audi claimed power output of 414, so it's safe to assume with the same driver/conditions that the Saloon will feel closer to it's output, followed by the Avant & then the Cab.

Power & wieght will always be the biggest contributors.

Look at the stats. An E60 M5 claims the same 0-60 time as the B7 RS4 saloon, however it's 100BHP more powerful, but weighs around 300KG more. The C5 RS6 posts the same 0-60 time as the B7 RS4, but is 170BHP more powerful, however a phat 1/2ton heavier.

I've not to the cab, I've driven the cab for months and yes the weight is definitely a factor. All I'm saying is that I reckon the B7 is down on power and something isn't right. Jim's car now feels bang on.

What was wrong with Jim's car & what's been done to fix whatever the problem was/is?

[W8PMC]

I got my weight from the audi website, they list the saloon as 1650, avant 1845

Think that's Saloon & Cab (not Avant).

According to Official UK Tech Data, Saloon is 1650KG Unladen & Avant is 1710KG.

[Contigo]

Nothing was wrong with it, it was stock. Mine was stock. All I'm saying is that now with the work done to it, it feels like it producing the right power and feels as reponsive as it should have been froim Audi.

[W8PMC]

I think we're talking at cross-purposes here...

We can all make up our own minds about whether the cars produce the Audi quoted figures, but the real question is why the variance?

We have a 20% spread on cars with no VAGCOM faults thrown up.

Now if someone can confirm that the difference between running 275/30's at 25psi and 255/35's at 50psi is 40hp, then we know the answer.

Conversely, if someone can confirm that the TC was switched off on all cars prior to running, we know that there is a good chance the EDL isn't screwing with things.

Similarly, if the power flap which comes online @ >5000 rpm is f**ked on some cars (MacRS4 & Klauster?), then effectively isn't the mass flow rate choked and power will be down?

I have to say I find the RS4 study guide ambiguous because to my mind the RS4 does not have a variable intake manifold, yet the text makes reference to a "intake manifold changeover valve"...

Is their really a big variance in the cars true output, or just as i suspect a difference in what the Dyno states, which i think we can now see is not really even a safe benchmark.

As i've said in previous posts, a low Dyno output would give rise to further investigation, however if the cars with much lower outputs according to the Dyno, perform as they should on the road & are no slower that those on the dyno that report a much higher output, it's safe to assume where the weakest link is.

My car is DMS tuned & has a Milltek cat-back. Like other B7's i've run at VMAX & have seen a maximum speed IIRC of 172MPH through the trap (speedo was 180MPH). Ran out of runway but the speed was still climbing.

I've seen GPS speeds of 180 & 181MPH in Germany, but again ran out of tarmac or balls to push further.

This speed was about 50-100RPM off the rev limiter in 5th Gear, so i still had the entire range of 6th gear available. Aerodynamics would restrict at this speed, but i'd happily guess my car would see North of 190MPH with enough tarmac.

[W8PMC]

Nothing was wrong with it, it was stock. Mine was stock. All I'm saying is that now with the work done to it, it feels like it producing the right power and feels as reponsive as it should have been froim Audi.

So stock it was down on power (by how much?) & now it's been tuned (by who?) it's up at where it should have been stock?

[Contigo]

Dunno how much it was down, how do we prove it as you simply rubbish dyno's! It's bullshit apparently. I'm talking real world driving after having had other cars to compare and in the real world it didn't feel like a 420bhp car.

[P_G]

All in your opinion. Which of course you are entitled to.

I imagine comparing one bum dyno to another is as widly contrasting as comparing on Dyno Dynamics Road to another?

[Contigo]

Yes probably but if it is down (my feelings) don't the RR results go someway to backing this up?

[P_G]

If we knew the r/r was accurate yes, but we don't. The day was very good and very well organised but as said below there were too many variables which included;

No logging of different tyre sizes and pressure and compound and tread depth
Differing engine temparatures and heat soak factor
Differing gearbox temperatures
ESP switched on, off, fully off? Vario-split power transmission interference?
IMO inadequate ventilation and gas extraction on that particular day
Differences between one Dyno Dynamics Road and another (Paramount's was 20bhp down in SRR and 15bhp down on Weltmeisters all using the same DD software and roads)

It proved there was a large number of cars within 5%-10% of each other bhp wise which can be accounted by the first three factors listed above which was about all I wanted to see from the day. Those who weren't in that band found faults with their cars and have by deduction managed to get them rectified which is a good result.

Like said r/r are good for tuning your own car, get a benchmark OEM figure in, modify the car in whatever way you are doing so and then look again to see what the (hopefully) gain or loss is.

I, like you it sounds, have been on or driven cars you you think are down on power but when you put it on a dyno it is spot on or above, some cars just drive like that. And then being a B5 RS4 owner you are alos used to the forced induction surge which as much as you try to neutrliase yourself from it when going into a N/A car, I subconsciously feel the latter is slower. Until I look at the speedo.

[rAudiguy]

Conversely, if someone can confirm that the TC was switched off on all cars prior to running, we know that there is a good chance the EDL isn't screwing with things.

J<

I got in everycar and made sure they were all the same.

Aircon off
TC off
DRL's off
Satnav off
Headlights off
heated seats off

every car was the same on the day I give you guys my word!! only variant was PSi and oil & fuel etc.

cheeRS

Jim

[rAudiguy]

Who is the closest person to me who ran sub 360bhp? I'm happy to come meet you and do some runs to see real world differences.

Phil we need to go do some more runs and also get yours on the Dyno.

No logging of different tyre sizes and pressure and compound and tread depth
Differing engine temparatures and heat soak factor
Differing gearbox temperatures
ESP switched on, off, fully off? Vario-split power transmission interference?
IMO inadequate ventilation and gas extraction on that particular day
Differences between one Dyno Dynamics Road and another (Paramount's was 20bhp down in SRR and 15bhp down on Weltmeisters all using the same DD software and roads)

I think we can say heat soak isn't as big as we thought bearing in mind both mine and robs cars ran later in the day having sat for 4 hours and were within 5bhp of the earlier results.

I'm going to run on Surrey soon to find out if she runs 20bhp up on Paramounts. Be well happy to see 430+