From 1955 to 1972, Chevrolet was the 800-pound gorilla on the new car performance scene. It moved iron by the millions, and during that period created more classic automobiles than all the other brands combined. Whether you are talking about looks or power, Chevy had the whole combination. Sure, once in a while someone would unleash a race car with license plates that could give the Bow Tie guys a run for their money. But the masses knew, if they wanted reliability, comfort, and the most bang-for-their-buck, the closest Chevy dealership was the place to shop.
Over time these cars became legendary, and like most legends their stature grew to epic proportions. Going back through yellowed magazine pages is a grand undertaking that takes an objective eye to separate the hyperbole from reality. Beginning with this article, we are starting a new series in Super Chevy. The goal is to see how some of these amazing vintage supercars actually perform in bone-stock trim on a modern chassis dyno.
When you read this and future stories in the series, keep in mind that prior to '72, GM rated its horsepower and torque in gross numbers-that's an engine on a dyno with no accessories hooked up, open headers, and maximized carb and ignition tuning. Some of the numbers on the following pages may surprise you, but we present them strictly for the sake of science.
For a baseline vehicle, we used Project Homewrecker, a '72 Corvette with a 383. We thought it perfect for the job since we had engine dyno numbers similar to gross measurements, but had yet to test it on a chassis dyno. The stroker is backed by an M22 four-speed and the IRS contains 3.70:1 gears. On an engine dyno with open headers, no accessories, and the same 750 cfm double pumper carb, it put out 425.8 hp and 473.8 lb-ft of torque. On Super Chevy's brand-new, state-of-the-art Dynojet (www.dynojet.com), it made 283 hp at 5,000 rpm and 341 lb-ft of torque at 3,900 (SAE net correction). That's with everything hooked up-alternator, power steering pump and Vintage Air A/C compressor. Eye opening, isn't it?
Got an early muscle car you'd like to have dyno tested for our articles? Shoot us an email at firstname.lastname@example.org. Include a photo of the car and all the pertinent info about it.
1970 LS6 Chevelle
Considered to be the ultimate muscle car of the golden age, the LS6 Chevelle was the biggest brute on the streets in its day. Spec'd out by GM at 450 hp, it came with 11:1 compression, rectangular port high-performance heads, solid lifter cam, aluminum intake and Holley carburetor. If you don't count the L72 427's early rating in the '66 Corvette (450 hp), the LS6 would be the most powerful engine to ever make residence between a Chevy's fenders until the LS7 came out in the 21st century Z06.
The example in our test belongs to Bob Phelps. A long-time drag racer, Bob has what could mildly be called a love affair with Chevelles, owning more than a dozen. This original Cranberry Red SS454 car left the Lakewood/Atlanta plant with a TH400 and 4.10 Posi-equipped gears. It has manual steering, and breathes through stock cast iron manifolds, mufflers, and the factory A.I.R. emissions system. This car is pretty much as it left the Denooyer Brothers Chevrolet lot in Kalamazoo, Michigan, in 1970. Recently it scored 997 points out of a possible 1,000 at a show.
"This is as close as you can get to going back in time 41 years," noted Editor Jim Campisano. "The red-on-red color combo made me weak, but it was nothing compared to what happened when I put the pedal to floor. The air-fuel ratio/carb tuning was spot-on and the 454 performed flawlessly-even the choke works. The minute I dropped the hammer, the engine accelerated the rollers with authority."
|On the Dyno