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I was watching an old episode of My Classic Car or something the other night and they were checking classic muscle car engines--dyno'd horsepower versus advertised horsepower. In every case, the real horsepower was considerably above the advertised.

For you that have dyno'd your GT 500 as delivered, what are your horsepower numbers saying?
 

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they did that so that insurance would be lower for the buyers and then they could sell more cars.

How many of us would not buy a GT500 is it was rated at 250hp, but we all knew it got 500?
 

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Mine dyno'd at 458 rwhp bone stock. I guess that is roughly 525 flywheel hp.

Stew
 

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Insurance, costs back then were high and the higher the advertised "Hp" the higher the insurance and I am sure it was the difference in making decisions. Manufactures purposely advertised lower numbers as youth was there targeted market area. Also the younger the age the higher the insurance cost.
I am actually surprised that my insurance on my Shelby is as low as it is because i would have thought insurance companies would be all over this and there are some limits I am sure that people would not touch the car because of the cost. Depending on how these cars are wrecked or involved in street racing incidents I am sure the insurance prices will reflect that number. So I know it's tough and I am surprised I haven't gotten a speeding ticket yet because it is tough to stay under even just cruising. I liken it to the Super Sport bikes out there as it is hard to just hold back as they are made to be driven fast. Anyways just my opinion on that.
The HP number i see advertised now seem to be pretty accurate now a days and I remember when Ford advertised one of the Mustangs years ago and the advertised HP was way higher then what they were. Lots of complaints about those cars Ford had to deal with. I am sure others here can add more detailed information and experiences.
 

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Yes, some of the supercharged Cobras a few years back didn't make advertised horsepower so Ford pulled them, took a step back and released the "terminator" engined Cobras which most will tell you are under-rated just like in the old days. I was shocked that there was NO insurance cost difference between a Mustang GT and a Shelby GT. They go strictly by the vin, and as far as my insurance company was concerned, all they saw when they looked at the vin was a regular old Mustang GT......
 

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I was shocked that there was NO insurance cost difference between a Mustang GT and a Shelby GT. As far as my insurance company was concerned, all they saw was a regular old Mustang GT......
Exactly at least that was one unexpected plus as far as cost for this car


:bluecap:
 

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I believe back in the 60's and early 70's they also measured HP within a fixed temperature of 60 something degrees...so the numbers would be higher then if they took that same motor and dyno'd it today.
 

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I believe back in the 60's and early 70's they also measured HP within a fixed temperature of 60 something degrees...so the numbers would be higher then if they took that same motor and dyno'd it today.
That's exactly what this episode of the show did--took factory high performance engines from the classic era and dyno'd them for research purposed. I've summarized the results below......

American Muscle Car Engine Comparisons

The rules were: 1) all production engines, not sohc Fords, etc., engines you’d find on the showroom floor. 2) Factory correct carbs & ignition systems. 3) Stock bore/stroke (allowed .60 over), stock heads, factory cam. Again, no ringers, nothing exotic, the engines you’d most likely meet on the street. The results below are numbers at the flywheel, and eliminate all other factors. Straight up, which legendary street engines were the most powerful.

Chevy 409
406 hp/430 torque

Ford 427
637 hp/554 torque

Pontiac 421
488 hp/470 torque

Dodge 426 hemi
820 hp/689 torque

Chevy 427
527 hp/461 torque

It's hard to capture all the info they give, but I believe the Ford 427 and the Hemi wound 6500 rpm and the others flatlined at 6000...but I could be wrong about that. I know the Ford went 6500.
 
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