Two shops use the same make dyno. Should I be able to expect comparable numbers between the two?
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Jan. 7, 2011 10:55 a.m. lewbud Reader
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Jan. 7, 2011 11:03 a.m. 92CelicaHalfTrac SuperDork
Depends on what dyno it is, how they have it set up, and weather conditions.
The short answer is "yes," though.
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Jan. 7, 2011 11:08 a.m. lewbud Reader
Would above ground v. in ground make any difference? Both shops use a Dynojet.
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Jan. 7, 2011 11:12 a.m. Keith SuperDork
No, that's just packaging, the drum should be the same size. If the operators are good and the dynos are set up well and you use the same correction factors (which should negate small climatic changes), numbers should be pretty close.
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Jan. 7, 2011 11:36 a.m. lewbud Reader
Thanks guys, that's what I thought.
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Jan. 7, 2011 1:46 p.m. bradyzq Dork
92CelicaHalfTrac wrote:
I would qualify that by adding "for inertia dynos."Depends on what dyno it is, how they have it set up, and weather conditions.
The short answer is "yes," though.
With loading dynos, where the operator controls the resistance, numbers can vary quite widely.
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Jan. 7, 2011 2:05 p.m. Tom Heath Webmaster
Also, you'll want to check how recent the calibration dates are.
There are some models of dynojet equipment that can no longer be calibrated; we've seen some pretty significant deviations from one setup to another. One shop (that shall remain nameless) hadn't done any maintenance or calibration to their machine in years. It was pretty consistent to itself, but seemed to be 10 horsepower off what I've seen my car do on identical models in other shops.
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Jan. 7, 2011 2:46 p.m. Keith SuperDork
bradyzq wrote:
92CelicaHalfTrac wrote:
I would qualify that by adding "for inertia dynos."Depends on what dyno it is, how they have it set up, and weather conditions.
The short answer is "yes," though.
With loading dynos, where the operator controls the resistance, numbers can vary quite widely.
Since lewbud mentioned they were both Dynojets, I was answering under that assumption. A dyno with a different measuring technique can give different numbers of course. For example, our old Dynojet and our new Rototest can give very similar numbers if the tests are designed properly, but the shape of the torque curve on boosted cars has a tendency to change due to the difference in how they load the car.
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Jan. 8, 2011 6:23 p.m. bradyzq Dork
Keith wrote: Since lewbud mentioned they were both Dynojets, I was answering under that assumption. A dyno with a different measuring technique can give different numbers of course. For example, our old Dynojet and our new Rototest can give very similar numbers if the tests are designed properly, but the shape of the torque curve on boosted cars has a tendency to change due to the difference in how they load the car.
I agree, but the fact that you can MAKE your Rototest output similar numbers to a Dynojet's, depending on your technique (ramp rate etc), reinforces my point.
BTW, congrats on the Rototest. Is it the only one in North America? If not, there can't be many others...
