Horsepower

[OUMike]

So after reading about the new ZR1 I started to grow a little curious about the engines power. I am fairly nostalgic when it comes to these things, and the older ZRs hold a special place for me, because they were one of the early cars that sparked a growing interest in high performance cars.

 

I did a little reading on horsepower and how its measured and come to find out the scale has changed vastly over the years. In 1995, the ZR-1 was 405 hp, but what would that be today? 450? 500? Starting in 2005 they switched to a measure called "SAE-certified" and it gave the 7.0L LS7 a 5hp over SAE (used from 1971).

 

To me it seems that changing the scale only enables auto manufactures to report bloated hp numbers. Wiki does a decent job of explaining things, but I think what confuses me is the why. Not sure why they would changed scales again in 05, when SAE (net) had been used for so long. Also wiki says the ZO6 only saw a 5 hp bump with the new system but the Caddy Northstar saw 19 hp jump. Why wouldn't it be a linear change?