Forgotten Powerhouse: Chevrolet's First Big Block Engine
The big-block V-8 is so synonymous with classic Chevrolet performance that it seems kind of weird that it wasn't introduced until almost the 1960s. Chevy had the D-Series for a brief period of time in the 1910s, but abandoned the V-8 until 1955, with the small-block. Then, answering a call from the Gods of Power, engineers designed the mighty W-series big-block in 1958, forever changing Chevy's performance and cementing their cars as some of the most intimidating on the streets.
Most likely because it sounds fast, Chevy liked to name its V-8s with a "turbo" prefix, like the Turbo-Fire small-blocks and the Mark IV Turbo-Jet big-blocks. The OG W-series V-8s went by "Turbo-Thrust" and, despite being naturally aspirated, kind of felt like they came with some extra boost. As the classic muscle car era developed, it would be the Chevy small-blocks that would dominate, but the foundation of performance was built upon the forgotten big-block monsters.
In order to give you the most up-to-date and accurate information possible, the data used to compile this article was sourced from GM and other authoritative sources, including Bring a Trailer.
Small-Block-Vs.-Big-Block
Small Block Vs. Big Block: Key Differences Explained
Size doesn't always matter when comparing Chevy small blocks and big blocks engines. Here's why
The Chevrolet Turbo-Thrust Big-Block V-8
Mecum
Chevrolet had a good thing going with its small-block V-8s, introduced in 1955, but wanted to develop a big-block for use in light pickup trucks. While initially intended for the Task Force trucks and their replacement, the C/K Series, Chevy made the "Turbo-Thrust" big block available to full-size passenger cars as well, because it was a torque-beast that could really break out the inertia on a big ride.
The 1958 W-Series big-block V-8 really was a monster, with a dry weight of nearly 700 pounds. The engine block was made of cast iron, had a bore center of 4.84 inches, and featured a "side oiling" lubrication system. It was an overhead valve design and, due to the low mass of the valvetrain, it was capable of running in excess of 6,000 RPMs.
W-Series Turbo-Thrust Specs
Displacement | 348ci | 409ci | 427ci |
|---|---|---|---|
Configuration | 90° V-8 | 90° V-8 | 90° V-8 |
Induction | Naturally aspirated | Naturally aspirated | Naturally aspirated |
Fuel System | 3 x 2 barrel | 2 x4 barrel | 2 x 4 barrel |
Bore x Stroke | 4.125 x 3.25 | 4.31 x 3.5 | 4.31 x 3.65 |
Compression Ratio | 11.25:1 | 11:1 | 13.5:1 |
Horsepower | 348 HP | 425 HP | 430 HP |
Torque | 364 LB-FT | 425 LB-FT | 575 LB-FT |
What really made the Turbo-Thrust stand out was its unique combustion chamber, which was located in the upper piston chamber, as opposed to the head, which is how most engines operate. This allowed for more complete combustion but also meant that the compression ratio could be changed without having to make new heads, which also required some retooling at the foundry. The biggest plus of an in-block combustion chamber, however, was that it created a relatively flat torque curve, which is ideal for larger vehicles. While the Turbo-Thrust was longer and wider than the small-block, it was actually 0.84 inches shorter, giving designers a little room to play with.
The Chevy 348 Turbo-Thrust
The first of the W-Series Turbo-Thurst big-blocks was the 348ci V-8, introduced in 1958 and was Chevy's top performance engine at the time. The base 348 with a four-barrel carburetor produced a respectable 250 horsepower, but there were some killer variants available. The "Special Turbo-Thrust" had a larger four-barrel and escalated things to between 305–340 horsepower. Then, there was the "Super Turbo-Thrust", which, like its name would suggest, was the ultimate, cranking it up to 348 ponies with a triple two-carb "Tri-Power" setup.
The 348 Turbo-Thrust In Action
Mecum
As awesome as the 348 Turbo-Thrust was, it wasn't intended as a performance engine and didn't cross over to the track or get a date with the Corvette. It did, however, make the Chevy land yachts sail a little smoother. The third-gen Bel Air, '58-'60 Impala, and the new-for-1958 Biscayne all got a power boost from the 348. The Task Force pickups also got an engine that established Chevy trucks as workhorses. The 348 Turbo-Thrust was only produced from 1958-1960 (1964 for trucks), but Chevy sold nearly 200,000 cars equipped with them, making it the Bowtie's first mainstream performance engine option.
Engine of 1963 Chevrolet Impala Z11 Terry Price
The Forgotten Powerhouse: Chevrolet's Rarest Engine
The 427 Z11 V-8 dominated the drag strip and could have owned the classic muscle car era had GM allowed it.
The Legendary 409 Turbo-Thrust
Mecum
The 348 was replaced in 1961 by the most legendary W-Series big-block, known simply as the 409. Technically, it was still a Turbo-Thrust, but thanks to the Beach Boys' hit "409" it just went by its cubic inches of displacement. Initially designed specifically for the 1961 Impala Super Sport performance package, the 409 Turbo-Thrust had a base model 360-horsepower version with a four-barrel Carter AFB carburetor. The version of the song, however, was a dual-quad, aluminum intake manifold, forged steel crankshaft that blasted out as many ponies as it had cubic inches.
1965 Impala SS Power And Performance
Engine | 409ci Turbo-Thrust V-8 |
|---|---|
Horsepower | 425 HP |
Torque | 424 LB-FT |
Transmission | Four-speed manual |
0-60 Time | 6.6 seconds |
Quarter-mile | 14.9 seconds |
Top Speed | 142 MPH |
The 409 was the same block as the 348, but it was bored out to 4.31 inches and stroked out to 3.5 inches to get the extra volume. In addition to the Impala SS, the 409 was optional on the full-size Bel Air and Biscayne, but again wasn't made available to the Corvette. Chevy had a tendency to make their most powerful engines available to the "Vette, and in 1961 the 409 was top dog, but it was a cumbersome engine that would have taken some tinkering to fit, and would have made the Corvette a nose-heavy performance nightmare. It was amazing in the full-size Impala, but not quite right for a smaller sports car.
The Six-Four On The Floor
Mecum
The Beach Boys may have been better served holding off until 1964 to write a love letter to the Impala SS 409 as it was substantially more powerful than the '61 they memorialized in song. Thanks to some tweaks and a higher compression ratio, the 409 was up to 425 horsepower and an equal amount of torque pound-footage in '64. This was the same number of ponies as the Chrysler 426ci Hemi V-8, which debuted in 1964 for NASCAR competition, and would make factory Mopars the fastest muscle cars of the Golden Age two years later.
Replacement And Displacement Theory
Chevy had a killer engine in the 425-horsepower 2x4 409, that would have made their cars the baddest on the streets in the 1960s. A '64 Chevelle SS with a 409 would have been one of the most legendary rides of the decade, but sinister forces conspired against it ever happening. In 1963, GM decided that all of its divisions were banned from equipping engines bigger than 400ci in intermediate cars. Granted, the Impala was a full-size, and would have been exempt, but Chevrolet inexplicably replaced the 409 Turbo-Thrust big-block V-8 in 1965 with the Mark IV 396, which was a 375-horsepower downgrade.
A parked 1962 Chevrolet Impala SS
10 Awesome Things About The Nearly Forgotten 1962 Chevy Impala SS
The 1962 Chevy Impala SS may be a forgotten gem, but it is competent enough to demand a place in muscle car history.
The Other 427 Big-Block
3/4 side view of 1963 Chevrolet Impala Z11 The Old Reliable
In 1963, Chevy stroked out the 409 to make 427 cubic inches of displacement for the Turbo-Thrust big block, creating the ultimate first-gen W-series engine. The 427, not to be confused with the Mark IV version that made the C2 Corvette a champion, was built for a limited-edition factory drag car Impala. Forever known as the Z11 Impala, its 427 was conservatively rated at 430 horsepower, and possibly accurately rated at 575 pound-feet of torque. This was a 10-second car, and no, that's not a misprint, the Z11 had the same kind of acceleration as modern supercharged 500+ horsepower supercars.
10-Second Or Better Cars
- 2023 Dodge Challenger SRT Demon 170 - 8.91 seconds
- 2022 Bugatti Chiron – 9.1 seconds
- 2021 Porsche 911 Turbo S Lightweight - 10.0 seconds
- 2022 McLaren 765LT Spider - 10.3 seconds
- 2023 Chevrolet Corvette Z06 - 10.5 seconds
- 2023 Lamborghini Huracán Tecnica - 10.6 seconds
- 1963 Chevrolet Impala SS Z11 - 10.8 seconds
- 2023 Dodge Charger SRT Hellcat Redeye - 10.8 seconds
- 2022 BMW M5 CS - 10.9 seconds
- 2021 Porsche Panamera Turbo S - 10.9 seconds
The Z11, was a stripped-down version of the Impala with lightweight aluminum body panels, which took a little over 500 pounds off the regular production version. That diet, however, doesn't explain how this car could run a quarter-mile in the 10s, which goes back to how woefully underrated its output was. A 2023 Dodge Challenger SRT Hellcat Redeye hits the standing quarter-mile at 10.8 seconds, and it has a 797 supercharged Hemi V-8 engine. For the '63 Impala Z11 to beat that, it clearly had to have a little more than 430 ponies under the hood.
Impala Z11 Collector Car
Bring a Trailer
It has been widely reported that there were 57 1963 Impala Z11s made, but Chevy has only documented 50. That seems like a silly number to worry about because, either way, it's a super-rare set of wheels. The Chevy Impala is one of the most abundantly produced nameplates in American automotive history, so the law of supply and demand makes it one of the most accessible classic nameplates. The Z11, on the other hand, is as elusive as it is desirable, so they command top dollar. This killer '63 Z11 was bid to almost $300,000 on Bring a Trailer, which means that is how much, or possibly more, is what they are worth.
3/4 front view of red 1964 Chevrolet Impala SS
Why The Chevy Impala Is Still A Hot Commodity On The Used Market
From low riders to muscle cars to classic cruisers, the Chevy Impala has a broad appeal that drives a sizzling used car market.
The Underappreciated Legacy Of The Turbo-Thrust Big-Block
Mecum
Chevrolet's first big-block V-8 was clearly a killer platform with some amazing engines, but too many factors have conspired to damn it to obscurity. The W-Series Turbo-Thrust engines were never put into high-profile muscle cars or the Corvette, so for many classic Chevy performance aficionados, it's almost like they never existed. It didn't get the exposure of the Mark IV 427 Tri-Power C2 'Vette engine, nor did it gain the infamy of the 1970 Chevelle 454 LS6 big-block. Most of all, it was cheated out of its rightful place as a top Chevy V-8 by the stupid GM big engine ban.
The 396 big-block became the top engine for Chevy's Golden Age of American Muscle because the 409 and 427 Turbo-Thrusts were black-balled. A Chevelle or Camaro with up to 425 horsepower in the 60s would have been a lights-out ride that would have dominated the streets. There were actually dealers who exploited GMs COPO (Central Office Production Order) program to special order Camaros with second-gen 427s, but it would have been much cooler if Turbo-Thust big-blocks were factory options. It would have created a situation where nobody would remember a Charger R/T or Hemi 'Cuda.
