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Originally Posted by Vman455
It was explained several times: BSFC has nothing to do with throttle-stop testing since throttle-stop testing does not use fuel consumption as a measurement parameter.
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No, it was not explained at all, ever. A change in BSFC at a given throttle position necessarily results in a difference in power output, and therefore speed. Just because fuel consumption is not being measured doesn't mean a change in BSFC is irrelevant.
Someone insisting something incorrect has still failed to answer the question.
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Throttle-stop testing works on the principle that for a given throttle opening and over small changes in engine RPM, torque output is nearly constant.
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Power is torque * RPM / 5252. A change in engine RPM at a given torque necessarily means the power output is changing.
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On a vehicle with fixed transmission gear ratios, constant torque = constant force at the wheels, so a change in drag force will show up as a change in speed, and the ratio of the squares of each speed will be equal to the ratio of each drag area. That's it. No BSFC. Has nothing to do with this type of test.
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Horsepower determines speed, not torque. Since a changing RPM affects how efficiently fuel is burned, and therefore power output at any particular torque, it must affect speed non-linearly.