# Did Detroit 'Muscle Cars' Really Have Higher-Than-Rated Horsepower? **URL:** \ **Category:** Factual Questions\ **Created:** [December 10, 2003, 4:12pm UTC](https://boards.straightdope.com/t/did-detroit-muscle-cars-really-have-higher-than-rated-horsepower/218158 "2003-12-10T16:12:54Z")\ **Posts on this page:** 1\ **Showing post:** 12
**Author:** ![Blown\_Injected](https://avatars.discourse-cdn.com/v4/letter/b/a87d85/32.png) [@Blown\_Injected](https://boards.straightdope.com/u/Blown_Injected)\ **Post date:** [December 11, 2003, 1:34am UTC](https://boards.straightdope.com/t/did-detroit-muscle-cars-really-have-higher-than-rated-horsepower/218158/12 "2003-12-11T01:34:05Z")
> [@](#): > > \*Originally posted by Philster \* > \*\*You have it backwards. The published numbers are inflated versus today’s methods of testing and reporting. Today is more legit in terms of what the engine will produce in production mode, with real fuel, timing, etc. > > What they DID do was hold back the numbers relative to their era. > > So, if they had a 400hp motor (which might be 285 today), the might report it as 365, and this might be for insurance reasons, or just because the internal directive from the corporate decision makers was to cut back the HP (for image reasons, safety, etc). \*\* do not believe that is what the OP is asking about. Back in-da-day the ratings were net HP. Today they test the engines with all the accessories and exhaust in place so the numbers are less than if tested with nothing extra on the engine and using dyno headers. But on to the OP. YES, and it is still done today. That is one reason my Bonneville that weighs more and has less rated power than my buddies Honda still blows away his Honda. My Buick was rated at 235 HP------at 4,000 RPM’s. At 5,300 RMP’s it is more like 300+. Of course the area under the torque curve is what really tells the story. --- _[View the full topic](https://boards.straightdope.com/t/did-detroit-muscle-cars-really-have-higher-than-rated-horsepower/218158)._