I was reading an article in the last Hemmings Muscle Machines about a '62 Pontiac 421 Super Duty. I was surprised to read that actual horsepower was 465hp at the crankshaft with 505-lbs.ft. of torque, as tested by Motor Trend in 1962. Apparently the most current article isn't up on Hemmings site yet, but here is a link to another Super Duty article that contains the same info. The horsepower and torque info is found in Myth No. 3.
That's a whole lotta motor. The advertised 405 hp is impressive enough but 465 hp is just unreal. Here is the quote:
"Myth No. 3: The 421 produces 405hp. It doesn’t. Most estimates are in the 450hp range. In 1962 a Motor Trend road test of an identical car calculated that it was making 465hp at the crankshaft and 505-lbs.ft. of torque."
As you may know, many maufacturers were known to "underrate" their engines mostly for the insurance companies. It is a known fact that the Chyrsler 426 Hemi engine did not put out 425 HP. It was closer to 500-550 HP.
"That's Spenser with an "S", like the poet." Robert Urich, Spenser For Hire 1985
That's why the 60s was the greatest drag racing decade in history. The factory involvement in the horsepower war led to the greatest innovations in drag racing. The 409, 421 SD, 413/426 wedge, and the 390/406 were the basis for everything to come except the 392 Hemi which was already being modified with fuel injection, superchargers, and fuels like alcohol and nitro. Yep, all of the factory info released on these early 60s engines included underrated horsepower ratings.
For some reason, I had in my mind that the 421 SD was a 425 horse engine. The 465 info kind of surprised me.