RomRaider

two times seems about right to me.

I may sound stupid, but which format is the RR dyno reading? how should be the column sorted? and is there a particular file where I can retrieve these value you gave me?

Thank you for your time and help.

Okay I'm getting insane I think.

I attached one log of a pull I made. When I use the button "load from file" and then read from file, loading this doesn't work.

What should be the column format for it to work?
I did try to change the time format to 00:00:00.000; 00:00.000 and 00.000 without any success, always getting blank dyno or numbers like 104000hp.

I provided the files to load in the correct format in my previous post. Save each run to csv comma separated format.

You may need to use US number format to read from a log file rather than semi-colon separated and . for decimal.

yeeeesssssssssss.

I'm really sorry to have asked again. I misinterpreted your former post!

so I simply converted the time to a simple integer like this

or like this


and it does work! Thank you!!!!!!!

The time needs no change as it will use the first entry as the reference time.

Hello, i tried to understand how the road dyno calculates the wheel power. I dont get the same reults as the dyno.

I gues the programm calculates from engine speed change per time the vehicle speed change per time wich would be the acceleration. With what Newton said F=m*a we can now calculate acceleration force. Multiplied with vehicle speed it gets acceleration power in kW. The power which works in opposite direction is roll- and air resistance which have to be added to the calc. acceleration power.

The problem i see is that i dont calculate same accleration as the dyno does. I have to know which dv/dt is used. I have table from log attached, grey cells are interpolated, i wonder that the rpm for calc peak power wasnt in the table, so i guess the dyno interpolated this rpm point. I interpolated the time at calc peak power an then i tried with interpolated values 500ms before and after peak power, i took this 1 sec period and calculated from engine speed change in this 1 sec the vehicle speed change, but i dont get exact same kW numbers as the dyno.

Another question i would have is which number the programm takes for air density.


Here my calc in detail:

From table attached(500ms before and after peak power):
∆n = 638,773 (1⁄min)/sek

gives:
∆v = (638,773 1/min * 2π * 0,31715 m)/(60 sec/min * 2,49 * 2,93) = 2,908 m/s
which ist vehicle speed change per sec = dv/dt = a = 2,908 m/s²

Wheel radius for 225/45R17:
r_Rad = 17''/2 *0,0254 m/zoll+0,225*0,45 m = 0,31715 m

with:
F = m*a
F_B = 1542kg*2,908 m/s^2 = 4483,914N
P_B = F_B*v

Now vehicle speed at peak power:
v = (n*2π*r_Rad)/(i_G*i_D )
v = (5645 1/min * 2π * 0,31715 m)/(60 sec/min * 2,49 * 2,93) = 25,698 m/s = 92,511 km/h

Accelerationpower P_B:
P_B = 4483,914 N*25,6998 m/s = 115,225 kW

Power against the car:
P_W = m*g*f_Ro*v+ρ/2*c_w*A*v^3
P_W = 1542kg*9,81 m/s^2 *0,012*25,698 m/s+((1,227 kg/m^3 )/2)*0,29*2,09m^2*( 25,698 m/s )^3
P_w = 10,975 kW

Wheelpower P_Rad:
P_Rad = P_B+P_W = 115,225 kW+10,975 kW = 126,2 kW

The difference is (126,8 - 126,2)kW = 0,6kW which is quiet close already.
Uncertainties are air density and acceleration.
My question is mainly if anybody knows how the dyno calculates the car acceleration?

EDIT: wrong dynograph attached
2nd-5th: I am very sorry i messed something up in the calculations.

probably due to the fact that it is averaging on more than just one value that you calculated.

and 2kW is like less than the error induced by slight slope on the road, so nothing to be worried about.

Yes, your right. I know the value for wheel power will only be correct if there is no slope and also no wind while logging.

I also tried with the 50 and 10 ms period but my result got worse.

Maybe someone knows how the dyno calculates the value for acceleration.

The raw data collected to determine acceleration depends on whether the car is AT or MT.
You can see the raw data in the rr_system.log if you used the Dyno feature live while driving. Otherwise it looks for the time, etc. from the log file you provided it to calculate HP.
The curve is based on a polynomial fit, selecting a smooth factor changes the degree of the polynomial.
This tool is for tuning comparison only. From a baseline, make changes and then test under the same conditions as the baseline to see you results. It will never match the results of a dynamometer.

https://github.com/RomRaider/RomRaider/ ... i/tab/dyno


Dots represent the calculated values plotted on the graph, from which the curve is derived.

Thanks a lot! This really helped me.
How did you mange to make those dots visible?
Is there the possibillity to get the polynomial out of the logger somehow?

Its been a long time since I worked on that, I'd have to go and look at the code for a while.
You could probably do the same in a spreadsheet.

I have avoided spending time with the logger due to my ancient tuning computer. Recently got a new tuning rig and finally spent some time figuring out how to get the dyno working from some old logs.

Pretty cool feature. Thanks for the work that has gone into this!

Question and or request: Is there a way to scale the dyno plot HP and TQ values? It auto selects these values and this causes the lines to not cross at 5250. Its strange to look at after years of comparison.

Thanks!

Thats what i have done now, it was quiet easy actually. But excel can only interpolate polynomial function up to 6.degree.

Does anybody know if the smoothing factor is equal to the degree of the polynomial?

Yes it is.