Look folks, my first job was with Electro Dynamics (Division of General Motors). They made locomotives, generators and electric motors -Really big ones. All work was done at IITRI (Illinois Institute of Technology Railroad Institute).
First, there's a good indication that people on this thread do not fully read the posts. Please go back, read the posts and try to comprehend what is being said. -Not just the first couple words you see.
When an integrator purchases a general purpose motor (let's say a 16 cyl Caterpillar) and if it does not produce the horsepower at ANY given RPM shown on the horsepower/torque curve then, I can guarantee the motor will be returned and repaired, refunded or, be the exhibit in a lawsuit.
Maybe people here don't know how to read graphs. Pick an RPM on the x-axis, go up to either the HP or Torque line and get the value for that parameter. Take the engine and use a governor to hold the RPM at that chosen speed then test the motor's actual HP. It better be within a a few percent of what the graph says. If it's not then, the dyno test is wrong or the engine has a problem. -End Of Story.
BTW: There are many ways to actually/reliably read the HP of a engine. In the 2000 HP units I once worked on, the engines were connected to a massive electrical generator. The generator was connected to massive resistance load boxes (taking-up a good amount of the parking lot). The engine was set with a governor to a particular RPM (almost always 1800 RPM), the load was increased until it could no longer maintain the set RPM. Using Voltage, resistance and the known efficiency of the generator, the Wattage could be determined. Watts and Horsepower have a direct conversion. When engines were tested like this, data points would sometimes be taken at 100 RPM increments for the manufacturers stated range of operation. If your idea of a dyno graph is something other than this, then, you are not really talking about a dyno graph. I can assure you with absolute 100% certainty that from the perspective of electrical or mechanical engineering, real dynographs are produced in this way or, they use some other mechanism to waste energy and measure it's output.
If a company like Kubota (who makes diesel generators for AC units and gensets) provided dyno graphs that did not represent the engine's HP at any given RPM on the graph, they would be buying back a lot of engines.
First, there's a good indication that people on this thread do not fully read the posts. Please go back, read the posts and try to comprehend what is being said. -Not just the first couple words you see.
When an integrator purchases a general purpose motor (let's say a 16 cyl Caterpillar) and if it does not produce the horsepower at ANY given RPM shown on the horsepower/torque curve then, I can guarantee the motor will be returned and repaired, refunded or, be the exhibit in a lawsuit.
Maybe people here don't know how to read graphs. Pick an RPM on the x-axis, go up to either the HP or Torque line and get the value for that parameter. Take the engine and use a governor to hold the RPM at that chosen speed then test the motor's actual HP. It better be within a a few percent of what the graph says. If it's not then, the dyno test is wrong or the engine has a problem. -End Of Story.
BTW: There are many ways to actually/reliably read the HP of a engine. In the 2000 HP units I once worked on, the engines were connected to a massive electrical generator. The generator was connected to massive resistance load boxes (taking-up a good amount of the parking lot). The engine was set with a governor to a particular RPM (almost always 1800 RPM), the load was increased until it could no longer maintain the set RPM. Using Voltage, resistance and the known efficiency of the generator, the Wattage could be determined. Watts and Horsepower have a direct conversion. When engines were tested like this, data points would sometimes be taken at 100 RPM increments for the manufacturers stated range of operation. If your idea of a dyno graph is something other than this, then, you are not really talking about a dyno graph. I can assure you with absolute 100% certainty that from the perspective of electrical or mechanical engineering, real dynographs are produced in this way or, they use some other mechanism to waste energy and measure it's output.
If a company like Kubota (who makes diesel generators for AC units and gensets) provided dyno graphs that did not represent the engine's HP at any given RPM on the graph, they would be buying back a lot of engines.