Smart Performance dyno update and advice
Turbo Mini Forums

Hi,

Ive been trying to sort out the problems we had with the dyno on the shootout day.

I have only just got a responce from dynocom USA about the problem. (Great customer service, glad I spent 25k!)

Apparently - "With inertia tests on a 1250 the results will jump around a little since it is a low inertia DYNO"

Would have been good if they told me that in the first place.

They have also told me to update somthing in the System paramaters which "allows butterworth filtering"

Now here's a question for all the brainy folk.. wtf is butterworth filtering and how will it make a difference? Or are the just bullshitting me as per usual?

Chris

http://en.wikipedia.org/wiki/Butterworth_filter

Somewhat beyond the understanding of my feeble brain. However I am sure that someone on here will understand :)

Edited by John on 26th Oct, 2010.

If something is worth doing, it's worth doing half of.

Yer I read that.. then I came on here for a sensible answer lol

Well somewhere between the recorded voltage (not sure exactly what the rollers are measuring, but it will be presented as a voltage to the processor) and the output will be lots of clever maths.

And somewhre in this lot there will be filters. The filters basically limit what you measure and allow you to get rid of noise. Say if I wanted to measure something between 15khz and 20khz then I could use a band pass filter to get rid of everything else. No filter is perfect though and you have to compromise your limits. And with digital monitoring you have to be very carful with ailasing as you can end up with all kinds of shit.

The butterworth filter is just one way of filtering which they obviously have included in the software. What the parameters of the filter should be is anyones guess.

What I'd do, is find the setting, if it's a simple yes/no option then get a car on the rollers and do two runs, one with Butterworth filtering on and one with it off and compare the two.

As I say what the function of the filter is on your kit is I have no idea.

Edited by wil_h on 26th Oct, 2010.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

Yer its an on off selection

Good to see you are trying to sort the issues you have!

So from looking at the paper, what it's saying is a butterworth filter is a very precise and smooth electrical filter. That filters out unwanted signals. It effectively stops ripples occurring within it's filter band be it bandpass (filtering high and low frequencies) or lowpass (filtering out high frequencies) or highpass (filtering out low frequencies). But what your rolling road needs one for is beyond me!!