someone on the 2stroke list was talking about this recently, istr.
suggested using a railroad wheel (either he had one, or the railyard was
giving them out cheap) 'cause they're good solid steel, well balanced, and
strong enough to hold up under the rpm and acceleration/deceleration
loads. also machineable to get a smaller mass if desired. I also seem to
remember him saying he could do the data acquisition program pretty
easily, too, but I might be off on that. anyway, check a local railyard,
or another suggestion was a 35-gallon drum filled with cement. have to
get it balanced pretty good, though to use it as a roller. good luck
either way.
scott
On Wed, 8 Dec 1999, Andy Poling wrote:
>
> On Wed, 8 Dec 1999, Erik Quackenbush wrote:
> > I've been thinking about a chassis dyno for my garage but the $20-30K price
> > tag for a DynoJet seems a bit high. Does anyone know of a less expensive
> > chassis dyno? I know I can measure hp and torque on the road using a
> > recorder and some software but I'm really interested in doing it inside
> > where I can easily tweak and rerun.
>
> The DynoJet's are the only chassis dyno's that I'm familiar with, but you
> could conceivably construct your own equivalent. I don't think a dynojet
> would fit in most home garages anyway, unless you went with a pit (and your
> local building code probably won't let you)
>
> We know how a chassis dyno works: the rollers are a known fixed mass and
> size. We therefore know how much power it takes to accelerate them at any
> given rate (it's pretty straightforward physics). All you do is put a
> tachometer on the rollers and log their rpm over time as you accelerate them
> with the car.
>
> I guess the big hangup is constructing heavy rollers that aren't a hazard at
> high rpm...
>
> -Andy
>
> 72 Pantera - Rocky 91 Miata - Steve 96 A4Q -
>Rudolf
> 80 928 - Phantom 87 E350XL - Andylance 84 RZ350 -
>Sting
>
>
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