KPower: Calculation Accuracy and Precision

Hi everyone,

"I bought a diagnostic adapter with the 409.1 and Kpower software two weeks ago because I was tired of the unreliable products you find on eBay (they don't work with VAGCheck and don't function with newer control units)."

I've previously done performance measurements using the VAGCOM 311 cheap adapter and the "Whoopies P*****er" software, and I always got readings of around 135 hp and 280 Nm. With a friend's car (a Fabia 1.4), I got readings of 78 hp and 125 Nm.

Now, using Kpower and VAGCOM 409.1, my car achieves approximately 111 kW and 320 Nm, while my friend's car achieves 69 kW and 144 Nm.

I'm now curious about where this large difference comes from, or what tolerance is allowed with this calculation.

My car.
Seat Leon 1M - Vehicle weight of 1600 kg, including occupants and accessories, measured on a truck scale (accuracy of 25 kg).
with 1.9 TDI engine (standard output 81 kW/235 Nm, chipped to 103 kW/280 Nm).
Sequential tire fitting.

My friend's car.
Skoda Fabia - 1425 kg
with 1.4 16V engine (series 75 hp, NM unknown).

I either used the existing *.pom files directly, or I re-read the log files and also performed new measurements. The calculated values were obtained from three different paths, and an average was calculated from them (the deviation between the individual paths is less than 3%).

greetings

Hi,

The calculations are also performed using acceleration, but in a completely different way. Could you please post your log files so we can see what's going on?

Regarding the data:
- Seat Leon: Curb weight 1334 kg.
http://www.alle-autos-in.de/seat/seat_leon_19_tdi_stella_ktc1284.shtml

- Fabia: 75 horsepower, 126 Nm of torque, curb weight 1135 kg.
http://www.alle-autos-in.de/skoda/skoda_fabia_14_16v_classic_ktb1315.shtml#Motor
http://www.alle-autos-in.de/skoda/skoda_fabia_14_16v_classic_ktc1315.shtml

You specified weights of 1600 kg for the Leon and 1425 kg for the Fabia.
So, either you had the 'Fat Boys' on the scale in the trunk, or your scale isn't that great...
The differences in weight directly affect the result. So, if the Leon actually weighs only 1500kg instead of 1600kg, you get 111kW * (15/16) = 104kW. Assuming a realistic weight of 1300kg for the Fabia: 69kW * (1300 / 1425) = 62.9kW (85PS).

How much did your measurements diverge? Averaging is usually unnecessary if the data acquisition is correct.
The differences between the individual measurements are typically in the range of 1-2%.

Best regards, Rainer.

Okay, regarding the weight, I didn't mention the unladen weight.
To Leon ->
Sport trim level.
Vehicle registration document 1314 KG.
Fuel: approximately 50 kg (full tank).
Passenger weight 160KG <<-- the FatBoy is sitting on the handlebars
Approximate weight of items in the car: 100 kg (includes radio, speakers, subwoofer, amplifier, laptop, GPS, climate control system, and floor mats).

It weighs 1624 kg, but I only checked it on a scale, and it was just over 1600 kg there. That scale should be accurate; it's a large platform scale that you drive onto. I'm not sure if you know what I mean, but it's mainly used in agriculture.

The Fabia is secondary for now, and I only included it for comparison.

The 3% difference in the individual calculations is due to the fact that I used different test tracks and also experienced different weather conditions, and no track near us is perfectly straight over such a long distance.

Here's the log file that produces the best power curve; the performance is also slightly higher here, at 115 kW / 340 Nm. It was recorded near the Main-Danube Canal.

My question about the difference in measurements concerned Woopsies P... versus Kpower, as there are extremely large differences in my car's readings. I haven't had my car on a dynamometer (rolling road) even once, so I don't have any baseline values to compare. And, of course, whether the calculated power output is close to the actual power.

Quote:

Thursday, September 22, 2005, 15:18:01. 038 906 012 AT, "0000SG 2815. Group A: ,'005,,,,Group B:,'006,,,,Group C:, Not Running "Engine speed, Start injector quantity, Actual start of injection, Coolant temperature, Speed, Brake pedal, Cruise control, Cruise system," TIME, rpm, 2*A-3*BTDC, 2*A-3*BTDC, *C, TIME, km/h, F/F47/F36, Cl/Br/Re/Ac/on/on, 0, TIME, , , , , , , , MARKER, STAMP, /min, mg/R, °, °C, STAMP, km/h, , , , STAMP, , , , ,0.00,1491,19.8,0.2,89.1,0.32,38.0, 0 0 0, 000000,255.0,,,,, ,0.64,1533,19.8,6.4,89.1,0.96,39.0, 0 0 0, 000000,255.0,,,,, 1.28, 1680, 19.8, 6.2, 89.1, 1.60, 42.0, 0 0 0, 000000, 255.0, , , , , 1.92, 1890, 19.8, 5.7, 89.1, 2.24, 47.0, 0 0 0, 000000, 255.0, , , , , , 2.56, 2100, 19.8, 6.4, 89.1, 2.88, 52.0, 0 0 0, 000000, 255.0, , , , , , 3.20,2352,19.8,7.0,89.1,3.52,58.0,0,0,0,000000,255.0,,,,, 3.84, 2562, 19.8, 7.7, 89.1, 4.16, 64.0, 0 0 0, 000000, 255.0, , , , , , 4.48,2793,19.8,8.8,89.1,4.80,69.0,0,0,0,000000,255.0,,,,, 5.12,3024,19.8,9.9,89.1,5.44,75.0,0,0,0,000000,255.0,,,,, 5.76, 3213, 19.8, 11.2, 89.1, 6.10, 80.0, 0 0 0, 000000, 255.0, , , , , 6.42, 3423, 19.8, 12.5, 89.1, 6.74, 85.0, 0 0 0, 000000, 255.0, , , , , 7.06,3612,19.8,13.4,89.1,7.38,90.0, 0 0 0, 000000,255.0,,,,, 7.70, 3780, 19.8, 14.5, 89.1, 8.02, 94.0, 0 0 0, 000000, 255.0, , , , , 8.34, 3927, 19.8, 15.2, 89.1, 8.66, 98.0, 0 0 0, 000000, 255.0, , , , , 8.98, 4074, 19.8, 15.4, 89.1, 9.30, 102.0, 0 0 0, 000000, 255.0, , , , , ,9.62,4221,19.8,15.0,89.1,9.96,105.0, 0 0 0, 000000,255.0,,,,, 10.28, 4368, 19.8, 15.2, 89.1, 10.60, 108.0, 1 0 0, 000000, 255.0, , , , , , 10.92, 4641, 19.8, 9.5, 89.1, 11.24, 109.0, 1 0 0, 000000, 255.0, , , , , , ,11.56,3234,19.8,0.0,89.1,11.88,108.0, 1 0 0, 000000,255.0,,,,, 12.20,1806,19.8,0.0,89.1,12.52,107.0, 1 0 0, 000000,255.0,,,,, ,12.84,1029,19.8,1.5,89.1,13.16,106.0, 1 0 0, 000000,255.0,,,,, 13.48, 924, 19.8, 1.3, 89.1, 13.82, 105.0, 1 0 0, 000000, 255.0, , , , , , 14.14, 882, 19.8, 1.3, 89.1, 14.46, 104.0, 1 0 0, 000000, 255.0, , , , , 14.78, 882, 19.8, 1.1, 89.1, 15.10, 103.0, 1 0 0, 000000, 255.0, , , , , , ,15.42,903,19.8,1.1,89.1,15.73,102.0, 1 0 0, 000000,255.0,,,,, 16.06,903,19.8,0.9,89.1,16.38,100.0, 1 0 0, 000000,255.0,,,,, ,16.70,903,19.8,1.1,89.1,17.04,99.0, 1 0 0, 000000,255.0,,,,, 17.36, 903, 19.8, 1.1, 89.1, 17.68, 97.0, 1, 0, 0, 000000, 255.0, , , , , 17.99, 903, 19.8, 1.1, 89.1, 18.32, 96.0, 1 0 0, 000000, 255.0, , , , , , 18.64, 903, 19.8, 1.1, 89.1, 18.96, 95.0, 1, 0, 0, 000000, 255.0, , , , , 19.27, 903, 19.8, 1.3, 89.1, 19.59, 94.0, 1 0 0, 000000, 255.0, , , , , 19.92, 903, 19.8, 1.1, 89.1, 20.24, 92.0, 1 0 0, 000000, 255.0, , , , , , 20.55,903,19.8,1.1,89.1,20.90,91.0, 1 0 0, 000000,255.0,,,,, 21.21, 903, 19.8, 1.1, 89.1, 21.53, 90.0, 1 0 0, 000000, 255.0, , , , , , ,21.85,903,19.8,1.1,90.0,22.17,89.0, 1 0 0, 000000,255.0,,,,, 22.49,903,19.8,1.1,90.0,22.81,88.0, 1 0 0, 000000,255.0,,,,, 23.13, 903, 19.8, 1.1, 90.0, 23.45, 86.0, 1 0 0, 000000, 255.0, , , , , 23.77, 903, 19.8, 1.1, 90.0, 24.09, 85.0, 1 0 0, 000000, 255.0, , , , , 24.41,903,19.8,1.1,90.0,24.75,84.0, 1 0 0, 000000,255.0,,,,, 25.07,903,19.8,1.1,90.0,25.39,83.0, 1 0 0, 000000,255.0,,,,, 25.71,903,19.8,1.1,90.0,26.03,83.0, 1 0 0, 000000,255.0,,,,, ,26.35,903,19.8,1.3,90.9,26.67,82.0, 1 0 0, 000000,255.0,,,,, ,26.99,903,19.8,1.1,90.9,27.31,81.0, 1 0 0, 000000,255.0,,,,, ,27.63,903,19.8,1.1,90.9,27.97,80.0, 1 0 0, 000000,255.0,,,,, 28.29,903,19.8,1.1,90.9,28.62,79.0, 1 0 0, 000000,255.0,,,,, ,28.95,903,19.8,1.1,90.9,29.27,78.0, 1 0 0, 000000,255.0,,,,, ,29.59,903,19.8,1.1,90.9,29.91,78.0, 1 0 0, 000000,255.0,,,,, ,30.23,903,19.8,1.1,90.9,30.55,77.0, 1 0 0, 000000,255.0,,,,, 30.87, 903, 19.8, 1.1, 90.9, 31.19, 76.0, 1 0 0, 000000, 255.0, , , , , 31.51,903,19.8,1.1,90.9,31.83,75.0, 1 0 0, 000000,255.0,,,,, 32.15, 903, 19.8, 1.3, 90.9, 32.47, 75.0, 1 0 0, 000000, 255.0, , , , , 32.79, 903, 19.8, 1.3, 90.9, 33.11, 74.0, 1 0 0, 000000, 255.0, , , , , 33.43, 903, 19.8, 1.1, 91.8, 33.75, 73.0, 1 0 0, 000000, 255.0, , , , , 34.07, 903, 19.8, 1.1, 91.8, 34.39, 72.0, 1 0 0, 000000, 255.0, , , , , , ,34.71,903,19.8,1.1,91.8,35.03,72.0, 1 0 0, 000000,255.0,,,,, 35.35, 903, 19.8, 1.1, 91.8, 35.69, 71.0, 1 0 0, 000000, 255.0, , , , , 36.01,903,19.8,1.3,91.8,36.33,70.0, 1 0 0, 000000,255.0,,,,, 36.65, 903, 19.8, 1.1, 91.8, 36.97, 70.0, 1 0 0, 000000, 255.0, , , , , 37.29, 903, 19.8, 1.1, 91.8, 37.61, 69.0, 1 0 0, 000000, 255.0, , , , , , ,37.93,903,19.8,1.3,91.8,38.25,68.0, 1 0 0, 000000,255.0,,,,, 38.57, 903, 19.8, 1.1, 91.8, 38.89, 67.0, 1 0 0, 000000, 255.0, , , , , ,39.21,903,19.8,1.1,91.8,39.55,67.0, 1 0 0, 000000,255.0,,,,, ,39.87,903,19.8,1.1,91.8,40.19,66.0, 1 0 0, 000000,255.0,,,,, 40.51, 903, 19.8, 1.1, 91.8, 40.83, 66.0, 1 0 0, 000000, 255.0, , , , , , 41.15,903,19.8,1.1,91.8,41.47,65.0, 1 0 0, 000000,255.0,,,,, 41.79, 903, 19.8, 1.1, 91.8, 42.11, 64.0, 1 0 0, 000000, 255.0, , , , , 42.43,903,19.8,1.1,91.8,42.77,64.0, 1 0 0, 000000,255.0,,,,, 43.11, 903, 19.8, 1.1, 91.8, 43.43, 63.0, 1 0 0, 000000, 255.0, , , , , , 43.75, 903, 19.8, 1.1, 91.8, 44.07, 62.0, 1 0 0, 000000, 255.0, , , , , , 44.39, 903, 19.8, 1.1, 91.8, 44.71, 62.0, 1 0 0, 000000, 255.0, , , , , , 45.03, 903, 19.8, 1.1, 91.8, 45.35, 61.0, 1 0 0, 000000, 255.0, , , , , , 45.67, 903, 19.8, 1.1, 91.8, 45.99, 61.0, 1 0 0, 000000, 255.0, , , , , 46.33, 903, 19.8, 1.1, 91.8, 46.65, 60.0, 1 0 0, 000000, 255.0, , , , , , 46.99, 903, 19.8, 1.1, 91.8, 47.33, 59.0, 1 0 0, 000000, 255.0, , , , , , 47.65, 903, 19.8, 1.1, 91.8, 47.97, 59.0, 1 0 0, 000000, 255.0, , , , , , 48.29, 903, 19.8, 1.1, 91.8, 48.61, 58.0, 1 0 0, 000000, 255.0, , , , , 48.93, 903, 19.8, 1.1, 91.8, 49.25, 58.0, 1 0 0, 000000, 255.0, , , , , , 49.57, 903, 19.8, 1.1, 90.9, 49.87, 57.0, 1 0 0, 000000, 255.0, , , , , ,50.21,903,19.8,1.1,90.9,50.55,57.0, 1 0 0, 000000,255.0,,,,, 50.87, 903, 19.8, 1.3, 90.9, 51.19, 56.0, 1 0 0, 000000, 255.0, , , , , ,51.51,903,19.8,1.3,90.9,51.83,56.0, 1 0 0, 000000,255.0,,,,, ,52.15,903,19.8,1.1,90.9,52.47,55.0, 1 0 0, 000000,255.0,,,,, ,52.79,903,19.8,1.3,90.9,53.11,54.0, 1 0 0, 000000,255.0,,,,, ,53.43,903,19.8,1.1,90.9,53.77,54.0, 1 0 0, 000000,255.0,,,,, ,54.09,903,19.8,1.1,90.9,54.41,53.0, 1 0 0, 000000,255.0,,,,, ,54.73,903,19.8,1.1,90.9,55.04,53.0, 1 0 0, 000000,255.0,,,,, ,55.36,903,19.8,1.1,90.9,55.69,52.0, 1 0 0, 000000,255.0,,,,, ,56.01,903,19.8,1.1,90.9,56.32,52.0, 1 0 0, 000000,255.0,,,,, ,56.65,903,19.8,1.3,90.9,56.97,51.0, 1 0 0, 000000,255.0,,,,, ,57.29,903,19.8,1.3,90.9,57.63,51.0, 1 0 0, 000000,255.0,,,,, ,57.95,903,19.8,1.3,90.9,58.27,50.0, 1 0 0, 000000,255.0,,,,, ,58.58,903,19.8,1.1,90.9,58.91,50.0, 1 0 0, 000000,255.0,,,,, ,59.23,903,19.8,1.1,90.0,59.54,49.0, 1 0 0, 000000,255.0,,,,, ,59.86,903,19.8,1.1,90.0,60.19,48.0, 1 0 0, 000000,255.0,,,,, ,60.51,903,19.8,1.1,90.0,60.82,48.0, 1 0 0, 000000,255.0,,,,, ,61.15,903,19.8,1.3,90.0,61.49,48.0, 1 0 0, 000000,255.0,,,,, ,61.80,903,19.8,1.3,90.0,62.12,47.0, 1 0 0, 000000,255.0,,,,, ,62.44,903,19.8,1.1,90.0,62.76,47.0, 1 0 0, 000000,255.0,,,,, ,63.08,903,19.8,1.3,90.0,63.40,46.0, 1 0 0, 000000,255.0,,,,, ,63.72,903,19.8,1.1,90.0,64.04,45.0, 1 0 0, 000000,255.0,,,,, ,64.36,903,19.8,1.1,90.0,64.68,45.0, 1 0 0, 000000,255.0,,,,, ,65.00,903,19.8,1.1,90.0,65.34,44.0, 1 0 0, 000000,255.0,,,,, ,65.66,903,19.8,1.1,90.0,65.98,44.0, 1 0 0, 000000,255.0,,,,, ,66.30,903,19.8,1.1,90.0,66.62,44.0, 1 0 0, 000000,255.0,,,,, ,66.94,903,19.8,1.3,90.0,67.26,43.0, 1 0 0, 000000,255.0,,,,, ,67.58,903,19.8,1.1,90.0,67.90,42.0, 1 0 0, 000000,255.0,,,,, ,68.22,903,19.8,1.3,90.0,68.56,42.0, 1 0 0, 000000,255.0,,,,, ,68.88,903,19.8,1.1,90.0,69.20,42.0, 1 0 0, 000000,255.0,,,,, ,69.52,903,19.8,1.3,90.0,69.84,41.0, 1 0 0, 000000,255.0,,,,, ,70.16,903,19.8,1.1,90.0,70.48,40.0, 1 0 0, 000000,255.0,,,,, ,70.80,903,19.8,1.1,90.0,71.12,40.0, 1 0 0, 000000,255.0,,,,, ,71.44,903,19.8,1.1,90.0,71.76,40.0, 1 0 0, 000000,255.0,,,,, ,72.08,903,19.8,1.1,90.0,72.40,39.0, 1 0 0, 000000,255.0,,,,,

Hi,

I've reviewed the log file, and everything seems plausible. If you can rule out the following potential sources of error, then it should be fine.
- Uphill when accelerating, flat surface when coasting?
- Are there any other rims/tires mounted that have a smaller rolling circumference?

You could, for comparison, visit a proper dynamometer with a good fan (otherwise the intake air temperature will rise too much and the power will decrease). For example, you could go to the ADAC. There, you can also have the speedometer reading checked at the same time (to account for any correction factors if you have different tires).

Best regards, Rainer.

Okay, so we have 15-inch standard tires, no downhill slope during acceleration, more like a 1% incline, and when rolling to a stop, meaning that if the calculation is really accurate, the car probably has more power than it needs.

Hi,

"Right, then your car is doing really well."

Best regards, Rainer.