traffic142

You read all about the good old days of HP in the 60's and wonder if our HP ratings are the same or worse than then? Does anyone know if our new 300HP is better or more accurate in numbers than the old HiPo 289/275 or the 65 Shelby 289/306??

Can anyone help out?

traffic142

I am looking to see how they were rated back then, and how they are done now. is our 300 hp the same or more than their 300 then

JoeP

Up until 1972 the numbers were SAE gross; since then they are SAE net.
Now under the 2006 revised standards the SAE ratings fromula is even stricter. SAE gross numbers are about 40-45% higher than net.
So 300h.p. today is about 420-435 h.p. in the 60's

The Boss Hog

Just to add on to what Joe said, Gross numbers were measured at the flywheel with no power-robbing accessories (alternator/generator, fan, etc.) hooked up and no exhaust restrictions (mufflers, small exhaust pipes). They represented the absolute max the engine could produce. The Net numbers were also measured at the flywheel but with all as delivered accessories and restrictions attached. The difference, as Joe stated, was significant. Additionally, NHRA classified pure stock cars by advertised HP verses curb weight so Detroit did a lot of fudging on the numbers. My old 335HP/383 CID '69 Roadrunner weighed approximately what my Mustang does, but could only muster a 14.75 @ 95 mph quarter (stock) on a good day.

The Boss Hog