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Calculate HP without Dyno?
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taqu
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 May 24 2012, 03:03 AM
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QUOTE(advocado @ Nov 13 2011, 09:42 PM) If you have your engine rpm & speed logged, together with car + driver weight, & aerodynamic drag you can calculate relatively accurate data, not sure how often the dynos are calibrated. Just a sidenote for dynos where do they plug in the engine to read the rpm? Actually that's how inertia dyno like Dynojet works. Instead of car+driver weight, it uses the roller's fixed weight. I've done this to my Exora Bold CFE. Using home-made Excel. Something like this :  The formulas are explained here : http://www.herberts.org/wayne/valk/valktorque.htmI added aerodynamic drag & rolling resistance formulas for final values. Looks pretty accurate to me. |
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taqu
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May 24 2012, 12:22 PM
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I use ELM327 Bluetooth OBD2 reader to log OBD2 data (RPM,speed,boost etc) directly.
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taqu
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May 24 2012, 01:06 PM
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GTech Pro is much more expensive than 1 dyno run.
They're IPhone apps than can calculate hp based on accelerometer data like Dynolicious & Track Day. Same concept as GTech Pro, much cheaper, pretty accurate, but only hp value no torque value.
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taqu
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May 24 2012, 03:10 PM
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QUOTE(Vervain @ May 24 2012, 02:27 PM) Iphone apps are crap. I've tested it and the results were far from actual after dyno. The gyro is not industrial spec tool. They rely on acceleration of the movement (which has a high tolerance) and GPS data (which is also crap AGPS & low frequency) to work out the estimation value. If you drive a 200hp car which weight less than 1 tonne, your HP indication will be higher due to power to weight ratio. Dynolicious & Track Day doesn't use GPS data. Probably it boils down to putting the correct info (vehicle weight etc), putting the Iphone in correct orientation (and stationery), and no jerking movement. Or the apps don't count aerodynamic drag / rolling resistance. I'll stick to my OBD data then  |
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