DIY software dynos - anyone use these?

[jdbubb at ix.netcom.com (Dan Bubb)]

I've got a Roaddyno.
It's OK for comparitive readings, but it's very sensitive to elevation
changes in the road and also to windy conditions.
Also, you will get quite different output depending on the gear you run in
even though you enter the gear ratio for calculation. Apparently, the
program doesn't take into account "geared rotational inertia" i.e. anything
that's geared up through the gearbox. And, quite frankly, there's no way to
assume or calculate a number for this inertia, so it's simply left out.
Bottom line?
You have to run the same piece of road, on a no wind day, with similar
ambient conditions in the same gear to get decent repeatability.
And, you have to not shoot your mouth off on the numbers you get since the
correction factors for power loss to correlate to an actual dyno run are so
high you'd be laughed off the list!
I hardly ever use it, although now that you bring it up, it would be good to
show the shape of the power curve if you ran it on a flat piece of road.
Nice toy though!
Dan

----- Original Message -----
From: Mark <mardak@cogeco.ca>
To: <scirocco-l@scirocco.org>
Sent: Tuesday, September 23, 2003 8:10 PM
Subject: DIY software dynos - anyone use these?


> I've been looking at StreetDyno <http://www.tweecer.com/StreetDyno/,
> and RoadDyno <http://www.charm.net/~mchaney/roaddyno/>, and it's DIY
> brother,
> HomeDyno <http://www.charm.net/~mchaney/homedyno/homedyno.htm>
>
> Cool concept using WAV sound files created using inductive pickups (timing
> light pickup), and then computing torque to get hp numbers (by counting
> spark pulses of an acceleration run through the rpm range with car data
> including weight, gear ratios, etc.)  Basically measuring the acceleration
> of the car rather than a drum on a standard dyno...
>
> Anyone use these?  Comments?
>
> I downloaded the StreetDyno prerelease software, and I'm getting some
weird
> results using the provided config and wav files so I don't know if I
should
> shell out the $50 to buy it...
>
> A nicer/cleaner version using real-time datalogging straight to a laptop
> would be cool though - rather than record WAV files, load them into the
> computer and then analyze them...  Seems a little mickey mouse...
>
> Any better solutions out there?
>
> Thanks!
>
> Mark.
> 80 S
> 81 S  ABA/JH/4K
>
>
>
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