Quote:
Originally Posted by JamesNoBrakes
Didn't they rate HP different then?
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They did...Before 1971, engines were factory rated using a process defined by the Society of Automotive Engineers as 'Gross' horsepower. This figure was calculated on a test stand with no intake, exhaust or power-robbing accessories attached. After 1971, power levels dropped as manufacturers re-rated engines using the SAE's 'Net' process, which added intake and exhaust restrictions and the load of engine accessories, like the alternator and power-steering pump.
When the '72's came out, we were shocked at what was called "net rated" horsepower figures...that an lowered compression ratios (for the then new unleaded gas).