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Old 3rd March 2017, 19:13   #31
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Default Re: PerfExpert App - The Poor Man's Dyno

Quote:
Originally Posted by Sutripta View Post
The biggest problem with these systems is trying to work out how much the vehicle will squat under acceleration.
There is a parameter called "Pitch" that takes care of this. The App provides guidance like what value to use for the type of suspension - soft, sporty, and very stiff suspensions. I think the app compensates for the "squatting under acceleration" based on the value entered for the "Pitch" parameter.
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Old 3rd March 2017, 19:17   #32
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Default Re: PerfExpert App - The Poor Man's Dyno

^^^
Question is how to get the value for 'pitch'. For the average enthusiast, it is essentially a guestimate. And it directly affects the readings computed.

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Old 3rd March 2017, 19:25   #33
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Default Re: PerfExpert App - The Poor Man's Dyno

Quote:
Originally Posted by Sutripta View Post
^^^
Question is how to get the value for 'pitch'. For the average enthusiast, it is essentially a guestimate. And it directly affects the readings computed.

Regards
Sutripta
I just followed the PerfExpert guideline and provided 3 as pitch for the Jetta and Polo, as these suspensions are neither very soft nor very stiff.

However, there is an interesting procedure to accurately adjust pitch described in the PerfExpert forums. You could give it a try.

http://www.perfexpert-app.com/forum/...-le-pitch.html

Use Google Translate to translate the page.
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Old 3rd March 2017, 19:55   #34
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Default Re: PerfExpert App - The Poor Man's Dyno

^^^
If I understood what was being proposed in the link, it was
use an independent estimator for speed
fiddle with the value of pitch till speed matches for PerfExpert and the other method.

Have I got it right?

Regards
Sutripta
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Old 3rd March 2017, 21:07   #35
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Default Re: PerfExpert App - The Poor Man's Dyno

Quote:
Originally Posted by Sutripta View Post
^^^
If I understood what was being proposed in the link, it was
use an independent estimator for speed
fiddle with the value of pitch till speed matches for PerfExpert and the other method.

Have I got it right?

Regards
Sutripta
Yes. That is what I understood from the link as well.

But I do not understand how pitch would affect speed calculation. The speed is calculated from measured acceleration and the measured acceleration is on the actual acceleration on the wheels after the losses which would include transmission loss, rolling resistance and the acceleration loss due to pitch.

There is another link in the same thread which says access denied.

http://www.perfexpert-app.com/fr/for...terminer-.html

Let me see if getting membership to the PerfExpert forum will open up this thread.

EDIT: Even after I created an account in the forum, I get "Access Denied" error

Last edited by graaja : 3rd March 2017 at 21:12.
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Old 4th March 2017, 19:19   #36
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Default Re: PerfExpert App - The Poor Man's Dyno

Fiddling with parameter values to match results are hardly the hallmarks of a finely tuned precision instrument!

It is not to put down this class of 'dynamometers', far from it. For its price it is a steal. But one should also know its limitations. Even better if one knows why the limitations.

Change in pitch will affect results. Applies to ALL similar setups. It is a theoretical limitation. Cannot be worked around (in the context of mobile phones) by using costlier hardware, or better crafted (= normally costlier) software, or by loading the software with bells and whistles.

Quote:
Originally Posted by graaja View Post
But I do not understand how pitch would affect speed calculation.
It comes from the fact that one can't distinguish between (and thus separate) gravitational forces from inertial forces.

Regards
Sutripta
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Old 24th April 2017, 10:45   #37
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Default Re: PerfExpert App - The Poor Man's Dyno

Inspired by Graaja Sir, I too installed the App and went off for a test today morning en-route home from work. Got a closed patch of road (ORR, Hyderabad). Took advantage for 30 minutes.

Here are some images:

PerfExpert App - The Poor Man's Dyno-1.-welcome-screen.png

PerfExpert App - The Poor Man's Dyno-2.-swift-1300-ddis.png

PerfExpert App - The Poor Man's Dyno-3.-car-profile.jpg

PerfExpert App - The Poor Man's Dyno-4.-weights-added.png

PerfExpert App - The Poor Man's Dyno-5.-weather-details.png

PerfExpert App - The Poor Man's Dyno-6.-test-selection-gear-rpm.png

PerfExpert App - The Poor Man's Dyno-7.-start-go.jpg

PerfExpert App - The Poor Man's Dyno-8.-post-run-summary.png

PerfExpert App - The Poor Man's Dyno-9.-run-1.png

PerfExpert App - The Poor Man's Dyno-10.-run-1.png

PerfExpert App - The Poor Man's Dyno-11.-run-2.png

PerfExpert App - The Poor Man's Dyno-12.-run-3.png

PerfExpert App - The Poor Man's Dyno-13.-run-4.png

PerfExpert App - The Poor Man's Dyno-14.-all-run-details-summary.png

Web links for the 4 run's:

Run 1

Run 2

Run 3

Run 4

Last edited by a4anurag : 24th April 2017 at 10:48.
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