Chevrolet Chevelle 1967 SS 700 Horsepower

A supercharged big block pushed past 700 horsepower on pump gas, custom suspension, and a nine-inch Ford differential under a 1967 Chevelle Super Sport. The factory version of this car was capped by a General Motors corporate memo that actually reduced its advertised horsepower that year, and the legendary 375-horsepower L78 was not even on the order sheet. Read on to find out how the badge and the build connect.

There is a particular kind of heresy in the muscle car world that gets forgiven the moment you hear the car run. Bolting a Ford rear axle under a Chevelle is one of them. So is running a supercharger on a car whose entire identity was built around naturally aspirated big-block torque. This 1967 Super Sport commits both, clearing 700 horsepower on pump gas through a built big block with a blower sitting on top of it, and sending all of it to a nine-inch Ford differential that a Chevrolet engineer in 1967 would have considered an insult. The strange part is that none of it actually contradicts what the SS 396 was originally supposed to be.

The Year the Badge Was Its Own Model

The Chevelle SS 396 occupies an unusual place in Chevrolet’s paperwork. It began life as an option package, but for 1966 it graduated into a series of its own with distinct style numbers, and it continued that way as a separate hardtop and convertible model through 1967 before eventually reverting to an option package later in the decade. That distinction matters to anyone verifying a car today, because for those specific years the SS identity is encoded in the VIN itself rather than buried in a build sheet that may or may not have survived. Chevrolet moved roughly 63,000 of them for 1967.

⚑ Featured Gear

Start Car Conversations →

As an Amazon Associate I earn from qualifying purchases.

A Corporate Memo That Cost the Chevelle Horsepower

The horsepower story for 1967 is a genuinely strange one. The optional L34 version of the 396 had been rated at 360 horsepower for 1966, and it dropped to 350 for 1967, not because Chevrolet detuned the engine in any meaningful way but because General Motors had imposed a corporate limit on horsepower relative to vehicle weight across its divisions. The standard engine on every SS 396 remained the 325-horsepower L35. In practical terms, buyers in 1967 were shopping from a menu that corporate policy had trimmed rather than one engineering had defined.

The Engine You Could Not Order From the Factory

The 375-horsepower L78, the solid-lifter big block that made the SS 396 genuinely fearsome, was simply absent from the 1967 order sheet. Buyers who wanted it had to arrange a dealer-installed conversion costing 476 dollars, and only 612 cars are believed to have received it. That is a remarkable footnote: the most desirable engine of the Chevelle’s most collectible era was, for one full model year, something you had to go around the factory to obtain. It also means that a genuine 1967 L78 Chevelle is one of the harder cars in the entire muscle car canon to authenticate.

What the Factory Cars Actually Ran

Those dealer-converted L78 cars performed to the standard the number promised. Period testing put them at 0-60 mph in 6.5 seconds and through the quarter mile in 14.9 seconds, running on the narrow bias-ply tires that made every muscle car of the era a traction exercise. That was quick in 1967 by any measure, and it came from an engine making its power the old way, through compression, camshaft duration and cylinder head flow, with nothing forcing air into it beyond atmospheric pressure and a well-designed intake tract.

The Suspension and Brakes Chevrolet Charged Extra For

Chevrolet’s chassis upgrades for the SS were meaningful but modest, and several of the most useful items cost extra. Higher-rate front springs and a thicker stabilizer bar came with the package. A four-speed manual replaced the standard three-speed for about 105 dollars. Front disc brakes were a 79-dollar option that a surprising number of buyers skipped, and F70x14 tires replaced the taller, narrower standard rubber. Read that list and it becomes obvious why the aftermarket suspension under a car like this one exists: the factory hardware was never designed for anything close to the loads a modern build generates.

Why Builders Reach for a Ford Rear End

The nine-inch Ford differential has become nearly universal in serious Chevrolet builds for reasons that have nothing to do with brand loyalty. Its hypoid gearset places the pinion well below the ring gear centerline, which increases tooth contact area and makes the unit exceptionally strong for its size. The third member drops out as a complete assembly, so changing gear ratios is a driveway job rather than a full afternoon under the car. Sixty years of drag racing have produced an enormous aftermarket around it, meaning axles, spools and housings are available in whatever specification a build requires.

Making Boost Work on Pump Gas

Making 700-plus horsepower on pump gas with a supercharger is a specific engineering problem rather than a matter of simply bolting on more boost. Pump fuel limits how much cylinder pressure the engine can tolerate before detonation, so a build like this one almost always runs reduced static compression compared with a naturally aspirated big block, and relies on careful ignition timing control plus either an intercooler or some form of charge cooling. Get any of that wrong and the failure is immediate and expensive. Get it right and the car will run all day on fuel available at any highway exit, which is the entire point.

Where 700 Horsepower Puts This Car

Seven hundred horsepower in a car weighing somewhere in the neighborhood of 3,600 pounds puts this Chevelle in a power-to-weight bracket that no factory muscle car of the era approached. The 375-horsepower L78 that made the Chevelle legendary produced roughly half the output. To put it another way, this build has a larger horsepower advantage over a factory L78 than the L78 had over the 250-horsepower two-barrel small-block Chevelle a neighbor might have driven to work in 1967. The gap is not incremental, it is generational.

The Same Idea, Pushed Fifty Years Further

For all that, the philosophy has not changed. Chevrolet’s original idea with the Chevelle SS was to take the largest engine it could reasonably justify and put it in a mid-size body that had no business carrying it, then charge extra for the parts needed to survive the consequences. A supercharged, 700-horsepower, pump-gas big block with a Ford rear end and custom suspension is that exact idea carried to its logical conclusion by someone who had access to five more decades of parts development. Chevrolet stopped where the warranty department told it to. This car simply kept going.

Share your thoughts in the comments below.

Republished by Blog Post Promoter