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Abbuzze
06-11-2005, 03:47 AM
Hi, I found an interesting Homepage.
It explains very good the difference between US-HP and german DIN PS, and how this figures are tested.

For the mentioned difference of 20% between both, I also found a german homepage where the difference is quoted with 5-15%, but we should take this into count when we discussing powerload and such things!!




SAE Net Horspower In 1972,

American manufacturers phased in SAE net horsepower. This is the standard on which current American ratings are based. This rating is measured at the flywheel, on an engine dyno, but the engine is tested with all accessories installed, including a full exhaust system, all pumps, the alternator, the starter, and emissions controls. Both SAE net and SAE gross horsepower test procedures are documented in Society of Automotive Engineers standard J1349. Because SAE net is so common, this is the standard we will use to compare all others.


SAE Gross Horsepower.

This is the old process that American manufacturers used as a guide for rating their cars. It was in place until 1971. SAE gross also measures horsepower at the flywheel, but with no accessories to bog it down. This is the bare engine with nothing but the absolute essentials attached to it; little more than a carb, fuel pump, oil pump, and water pump. Because the test equipment on the engine is not the same as in SAE net, it is impossible to provide a mathematical calculation between SAE net and SAE gross. As a general rule, however, SAE net tends to be approximately 80% of the value of SAE gross. SAE J245 and J1995 define this measurement.


DIN Horsepower

This is a standard, DIN 70020, for measuring horsepower that very closely matches SAE net. The conditions of the test vary slightly, but the required equipment on the engine and the point of measurement (flywheel) remains the same. Because the test conditions are so similar, it is safe to divide DIN horsepower by 1.0139 to arrive at SAE net. This value is so close to equal that for all but the most technical purposes DIN and SAE net are interchangeable.

An interesting thing.
Maybe anyone knows more about the circumstances about HP testing for flightengines in the 1930 or 40.

Abbuzze
06-11-2005, 03:47 AM
Hi, I found an interesting Homepage.
It explains very good the difference between US-HP and german DIN PS, and how this figures are tested.

For the mentioned difference of 20% between both, I also found a german homepage where the difference is quoted with 5-15%, but we should take this into count when we discussing powerload and such things!!

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">

SAE Net Horspower In 1972,

American manufacturers phased in SAE net horsepower. This is the standard on which current American ratings are based. This rating is measured at the flywheel, on an engine dyno, but the engine is tested with all accessories installed, including a full exhaust system, all pumps, the alternator, the starter, and emissions controls. Both SAE net and SAE gross horsepower test procedures are documented in Society of Automotive Engineers standard J1349. Because SAE net is so common, this is the standard we will use to compare all others.


SAE Gross Horsepower.

This is the old process that American manufacturers used as a guide for rating their cars. It was in place until 1971. SAE gross also measures horsepower at the flywheel, but with no accessories to bog it down. This is the bare engine with nothing but the absolute essentials attached to it; little more than a carb, fuel pump, oil pump, and water pump. Because the test equipment on the engine is not the same as in SAE net, it is impossible to provide a mathematical calculation between SAE net and SAE gross. As a general rule, however, SAE net tends to be approximately 80% of the value of SAE gross. SAE J245 and J1995 define this measurement.


DIN Horsepower

This is a standard, DIN 70020, for measuring horsepower that very closely matches SAE net. The conditions of the test vary slightly, but the required equipment on the engine and the point of measurement (flywheel) remains the same. Because the test conditions are so similar, it is safe to divide DIN horsepower by 1.0139 to arrive at SAE net. This value is so close to equal that for all but the most technical purposes DIN and SAE net are interchangeable. </div></BLOCKQUOTE>

An interesting thing.
Maybe anyone knows more about the circumstances about HP testing for flightengines in the 1930 or 40.