Double blown ’68 Chevelle, Pure Sound…

The unmistakable shriek of twin superchargers comes from a 1968 Chevrolet Chevelle, a car Chevrolet redesigned that year specifically to out-muscle the GTO and 4-4-2. Decades later, someone stuffed a pair of blowers under that long hood and turned a factory legend into a full drag-strip monster. Read on to find out what it takes to push a Chevelle past everything GM originally engineered.

Somewhere off camera, someone hits the throttle, and the sound that comes out does not belong to any stock muscle car, it is layered, mechanical, almost violent, the unmistakable shriek of two superchargers screaming in unison under a long steel hood. The car underneath all that noise is a 1968 Chevrolet Chevelle, a model Chevrolet redesigned from the ground up that year with a swooping Coke-bottle body built specifically to out-muscle Pontiac”s GTO and Oldsmobile”s 4-4-2 on the street and at the strip. What Chevy never intended, though, was for someone decades later to stuff a pair of blowers under that long hood and turn a factory legend into something closer to a drag-strip monster than anything that ever left a showroom floor back in 1968. The factory 396 was already enough to worry the competition badly, and it still is today. So what does it actually take to push a car like this past everything General Motors originally engineered it to be capable of doing?

The Coke-Bottle Redesign That Redefined the Segment

When the Chevelle entered its second generation for 1968, Chevrolet gave it a stiffer perimeter frame and that now-famous flowing bodyline, packaging real performance credentials to match the new looks that turned heads on dealer lots nationwide. The SS 396 became its own distinct series that year, sold as a Sport Coupe or convertible, and it came standard with a 325-horsepower Turbo-Jet 396 V8, with 350 and 375-horsepower versions available up the option sheet for buyers willing to check a few extra boxes and pay accordingly for the added performance and street credibility that came along with it.

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Why Builders Still Chase That Blown Sound Today

A factory 396 was never going to satisfy every owner forever, and the Chevelle’s stout Mark IV big-block architecture, a forged crank, deep-skirt block, and a bore-and-stroke combination built to survive abuse, made it a natural platform for forced induction decades after the assembly line stopped producing new examples. Twin superchargers layered on top of an already oversquare big-block produce a sound and a power curve nothing stock can match, which is exactly why builds like this keep circulating among enthusiasts long after the car’s original showroom rivals have been forgotten by most casual observers walking a modern car show today.

The SS 396 Option Codes That Matter Most

Chevrolet built 62,785 SS 396 Chevelles that year, all wearing heavy-duty suspension and wide F70x14 tires for a starting price that stayed comfortably under three thousand dollars, a genuine bargain for the performance on offer even before buyers started checking option boxes. Within that production run, the L34 and L78 engine codes represent the two most sought-after factory configurations today, with the solid-lifter L78 in particular commanding a substantial premium among collectors chasing the most authentic, highest-output version of the factory 396 available that model year from any Chevrolet dealer nationwide.

The Rock Crusher Four-Speed Behind the Wheel

Buyers who wanted to row their own gears could step up from a three-speed manual to the Muncie M20 or M21 four-speed, and the toughest combinations came with the heavy-duty M22, nicknamed the Rock Crusher for the distinctive whine produced by its straight-cut gears under load. That transmission has become something of a legend in its own right among Chevelle enthusiasts, prized not just for its durability behind a built big-block but for the unmistakable mechanical growl it adds to a car that already sounds nothing like an ordinary daily driver rolling through a quiet neighborhood street.

Superchargers Versus Turbos on a Big-Block Platform

Builders debating how to force-feed a big-block Chevelle generally split into two camps. Superchargers, mounted visibly atop the engine and driven directly off the crankshaft, deliver power instantly with no lag and produce the dramatic screaming exhaust note associated with cars like this one, while turbochargers tend to offer greater efficiency and higher potential horsepower ceilings but require more complex plumbing and typically hide beneath the car rather than bursting dramatically through the hood for everyone at a car show to see, hear, and photograph up close.

What a Numbers-Matching SS 396 Is Worth Today

A well-documented, numbers-matching SS 396 Chevelle in unmodified factory condition can command well into six figures at major auctions today, particularly examples carrying the rare L78 engine code and desirable options like the M22 transmission. Modified cars like this blown example generally trade in a different market entirely, valued more for build quality, documented horsepower, and driving experience than for factory originality, since a car running twin superchargers has permanently traded its numbers-matching status for something else collectors value in its own right on today’s modern build scene.

How Blown Builds Fit Into the Restomod Movement

The blown Chevelle sits squarely within a broader restomod movement that has reshaped how enthusiasts think about vintage muscle cars over the past two decades, blending period-correct styling with thoroughly modern power, suspension, and braking components underneath. Rather than treating originality as the only measure of a car’s worth, restomod builders and buyers increasingly prize a vintage body that delivers genuinely modern performance, which is exactly the philosophy behind stuffing twin superchargers under a fifty-year-old hood and letting the resulting shriek announce exactly what the car has become to anyone standing within earshot of it.

A Factory Legend Pushed Past Its Own Limits

What makes a build like this one resonate with enthusiasts is not just the raw horsepower, but the contrast between the factory legend the Chevelle already was in 1968 and what a dedicated builder can coax out of the same basic architecture decades later. Chevrolet’s engineers built a genuinely potent muscle car capable of embarrassing its GTO and 4-4-2 rivals on release, and the fact that a big-block Chevelle can still be pushed meaningfully further today, using the same fundamental block Chevrolet cast half a century ago, says something enduring about just how much performance potential was baked into that original 1968 design from the very beginning of its development.

How a Roots-Type Blower Actually Makes Power

Most of the visible superchargers poking through a hot rod’s hood, including setups like the one on this Chevelle, use Roots-type design, named for the Roots brothers who patented the basic rotor arrangement in the 1860s for use in industrial blowers long before anyone imagined bolting one to a car engine. Two meshing rotors spin inside a housing, pushing a fixed volume of air into the intake manifold with every revolution, and because they’re mechanically driven directly off the crankshaft via a belt, they deliver boost instantly at any engine speed rather than building gradually the way a turbocharger does. That instant responsiveness is part of what makes a blown big-block feel so different from a stock one at launch, and running two of them, rather than the more common single unit, is a build choice aimed at moving even more air through an already substantial 396-cubic-inch platform than one blower alone could manage.

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