Logging accelleration with Vagcom

[newsh]

Hmm, I assume that is coolant temp from channel 1?
70degs sounds rather low, and if the car was properly warmed up, I suspect the thermostat might not be working quite properly. I see coolant temps between 90-93degs in my RS2 logs, 90-92C for the RS4 and 99C for the A4.

Yes, coolant temp from channel 1. It seems to stabilise at 70deg, it will go higher in traffic but on the road thats it, I have to run the heater dial full red to warm the cabin. I suspect when its cold on the motorway it drops lower. I've been suspecting the thermostat and I guess this confirms it, the spring must be weak.

[newsh]

Espen, what would you estimate power to be from the 4.6 time?

BTW the car is running 225/50-16s (almost identical diameter to stock 205/55s)

[prj]

No I don't have a wideband, it was just from Vagcom. I need to get one really, been thinking about it long enough

Well, go on then.
You know which one to buy

[EspenW]

Espen, what would you estimate power to be from the 4.6 time?

BTW the car is running 225/50-16s (almost identical diameter to stock 205/55s)

What was the approx. test weight of the car with occupant(s)?
5 or 6 speed gearbox?

Here is a large database of FATS runs with estimated crank power for the S4's:
http://nyet.org/fats/?sort=FATS

Would be great if you could post the excel file with the log

[newsh]

Well, go on then.
You know which one to buy

Was thinking of the Vems Round But then there's that kit..

[newsh]

What was the approx. test weight of the car with occupant(s)?
5 or 6 speed gearbox?

Here is a large database of FATS runs with estimated crank power for the S4's:
http://nyet.org/fats/?sort=FATS

Would be great if you could post the excel file with the log

Car is an otherwise stock S2 Avant, 6 speed, spec says 1560kg unladen plus just me on board (100kg).

[newsh]

Here is a large database of FATS runs with estimated crank power for the S4's:
http://nyet.org/fats/?sort=FATS

Wow, that's deep

[URquattroGus]

By coincidence I was visiting a friend this weekend and we did something like this in his A3 1.8T, using VCDS or something or other vag com software we recorded 0-60 and quarter mile times. Not sure how accurate they are but it was a bit of fun. I think it was a new feature for the latest software release.

Can this be done on an S2 or is it only a later car with an ODB connector that will allow this?

Furthermore, in my car whioch uses a s6 AAN engine ECu in an ur quattro, would I be able to use vag com for any diagnostics? if so how would I connect?

[newsh]

Check S2 Central for the how-to. You just need to the K and L lines from the ECU which would normally come up in the fuse box, and a +12V and a ground.

[EspenW]

I did some checking over at Audizine, and super tuner Jason from AMD had much experience with FATS times for the 1.23 3rd gear of the B5S4 and 1.32 3rd gear of the B5 RS4 (and our cars). He says that the difference is consistently in the 0.2-0.3 range, so adding 0.3 to the time should be a conservative estimate when comparing with the S4 times like in the link above.

I suggest that you go weigh the car on a weighbridge to get the most accurate figure. Weigh the car with a full tank. One litre of petrol weighs approx. 0.75kg, so half tank will be close to 25kg lighter than full tank.

The FATS times are the result of the average power/torque in the 4200-6500rpm range, so both peak torque and peak power come into play.

Here are some of the results that I have measured. I have Vagcom results only from my own RS2 and the B5 RS4 that I tested, but I have tested some other RS2s with my MR Dyno logger, and I can get FATS times within 0.1s from that. I have adjusted the times to estimate the time would be with driver only. Here are FATS times along with measured horsepower (uncorrected for temp) at the wheels and claimed hp and nm at the crank:
Note that the measured power/torque at the wheels is uncorrected for temp and thus somewhat higher than if SAE/DIN corrected, but this makes it easier for comparison with the FATS times.
Claimed hp at the crank is always corrected for temperature.


My RS2:
Test weight with driver: 1620kg
FATS: 2.84s
Measured power at the wheels: 430ps
Measured torque at the wheels: 602nm
Claimed power at crank: Probably somewhere around 500hp and 700nm

MTM B5 RS4
Testweight with driver: 1775kg
FATS time: 3.8s
Measured power at the wheels: 370ps @7000rpm
Measured torque at the wheels: 490nm
Claimed power at crank: 463ps and 580nm

RS2 Hohenester Stage 5
Testweight with driver: 1703kg
FATS time: 4.1s
Measured power at the wheels: 322ps
Measured torque at the wheels: 414nm
Claimed power at crank: 400ps and 550nm


RS2 with Turbonetics Super 50, Wagner IC, etc
Testweight with driver: 1686kg
FATS time: 3.55
Measured power at the wheels: 363ps
Measured torque at the wheels: 475nm
Claimed power at crank: unavailable


FATS is great for comparison of real world performance between cars, as it covers an important powerband, and is very repeatable with the Vagcom, just remember that weight and temperature/elevation comes into play, so conditions must be similar (or corrected). Also a good idea to test at the same exact place each time.

[EspenW]

I've gotten some more feedback, and the difference between S4 and S2 gearing seems to center right at 0.25s, that means your best "S4" FATS time is right at 4.8s, and that is very solid.
Just goes to show that all out peak hp is not all that matter when it comes to making a fast car, it is the average power over the power band used for a certain pull that determines the outcome.

[newsh]

I've gotten some more feedback, and the difference between S4 and S2 gearing seems to center right at 0.25s, that means your best "S4" FATS time is right at 4.8s, and that is very solid.
Just goes to show that all out peak hp is not all that matter when it comes to making a fast car, it is the average power over the power band used for a certain pull that determines the outcome.

Thats true, the area under the curve is important as well as the peak

[Rusty]

I tried back-calculating power curves from GPS data and it's a bit of a faff TBH. The data is a bit sketchy and air resistance etc. can be accounted for but it's as much about trial and error as anything else. For distance or speed differential measurements though it's ideal. I'm sure that the VC data is similar to deal with, perhaps cleaner as there are no cyclic positioning errors but the speed is estimated rather than actual. For measuring fairly slow increases in RPM though, it works well. Only issue is that to get the data over a sensible time frame involves speeds that aren't too sensible...

[newsh]

Andy, The FATS thing is just a comparison of 4200 -6500rpm in 3rd. There are shedloads of people who've done the measurement, many of whom have dyno'd their cars. So there's a lot of data and it all averages out and you get a feel for how strong your car is, the actual HP numbers are not so important.
So go and run a log and post your time up!

[Rusty]

My FATS time is based on speed and not actual engine RPM so you need to reduce my time by the 7% fudge factor, thus 4.65 or so... but that's not strictly accurate as the enigne isn't in the S2 sweet spot, as it is on your FATS times and the S2 does tail off above the 6k5 marker.

I've just checked a log I have of a 3rd gear run, full interior etc. Simiklar outside temperature etc. too.

Time was 4.45s using a conversion factor from GPS speed to RPM of 77.9 RPM/mph. I know that there's 1bout a 5% error factor on the speedo though so again, that figure isn't as accurate as VAG Com data (although it's f'ing close).

I'd say that the times you're getting are comparable with mine John so a solid 300bhp. My coupe is about 2-3% lighter than the Avant but there's enough error on my measurements to negate much pontification on that.