how do manu measure bhp?

[Christopherrr]

just wondering how they do it...we obviously dyno...but do GM measure brake horsepower with accesories, exhuast, cats, filter installed???

Never knew how did it...anyone have any ideas?

[Black97]

Not sure either, found following links

http://www.zephyrus.co.uk/horsepoweranswer.html

http://www.akamoto.co.uk/info/torque-vs-horsepower.htm

http://yarchive.net/physics/horsepower.html

[Injuneer]

Up until about 1970, engine HP was called (as I recall) "SAE gross", and was basically a bare engine run on an engine dyno.... no accessories, limited intake and exhaust - nowhere near what you would actually see in your real car. In 1972 or so, they revised it to "SAE net" which required that the engine be run on the dyno with all the standard accessories, intake and exhaust. That's when the 1970 370HP LT-1 became a 1971 330HP LT-1 (emissions loss) became a 1972 255HP LT-1 (emissions + SAE rerating).