Chevrolet’s W‑Series big‑block V‑8, introduced for the 1958 model year, marked GM’s first move into true big‑block territory. Designed for both passenger cars and light trucks, the iron‑block V‑8 featured its combustion chamber in the block, not the head a radical design that treated compression changes with simple block modifications instead of costly retooling.
Why “W‑Series”?
Though often thought to refer to the scalloped “W‑shaped” valve covers, “W” was simply an internal project code used during development, one among X and Y designs. The W‑engine proved the winner, and the name stuck.Engine Sizes & Performance Options
348 cu in (1958–1961 for cars, through 1964 in trucks)
- Base Turbo‑Thrust: 250 hp, hydraulic lifters, single four‑barrel carb.
- Super Turbo‑Thrust: 280 hp, three 2‑barrel carbs, hydraulic lift cam, 355 lb‑ft torque @ 3,200 rpm.
- Special Turbo‑Thrust: ~305 hp, higher compression and bigger single carb.
- Special Super Turbo‑Thrust: top 348 version from 1960–61, pushing up to ~335 hp with mechanical lifters and higher compression.
409 cu in (1961–1965)
- Introduced in late 1961 for the Impala SS as 360 hp with a single Carter AFB carburetor and mechanical lifters.
- In 1962, a 380 hp version appeared with same setup plus a quad configuration variant rated at 409 hp using dual four‑barrels
- In 1963, power peaked with versions at 340, 400, and 425 hp, including a limited Z‑11 427 cu in crate‑type engine officially underrated at 430 hp.
Technical Highlights & Design Innovations
- The combustion chamber was formed within the cylinder by angling the deck at 74° and using a crowned piston, combining to create a wedge‑shaped chamber with vertical spark plug orientation for faster flame front and better low‑end torque.
- The side‑oiling system placed the main oil gallery low on the driver side, paired with a full‑flow filter and interchangeable heads across displacement variants.
- Valve train used tubular pushrods and stud‑mounted rocker arms—pushing oil upward to rocker gear and allowing higher revs (over 6,000 rpm in solid‑roller specs).
- The W‑engine shared bore centers with later big‑blocks but predated Chevy’s mark‑IV architecture by embracing its unique combustion layout .
Legacy & Aftermarket Life
Though discontinued by the mid‑1960s in favor of the more efficient Mark‑IV Chevy big‑block, the W‑Series engines remain iconic. Their broad torque curves, flexible displacement options, and rugged approach appealed to both passenger car and truck audiences of the era.Hot‑rodders still revive and upgrade them: for instance, modern builders have stroked early 348 cores to 437 ci, achieving 650 hp on pump gas, a testament to the W‑block’s enduring foundation.
Summary Table
| Engine | Years | Peak Power | Notable Features |
|---|---|---|---|
| 348 Turbo‑Thrust | ’58‑’61 | 250 hp | Base engine, hydraulic lifters, economical & torque‑rich |
| Super & Special Turbo‑Thrust | ’58‑61 | 280–305 hp | Multi‑carb setups, mechanical lifters, higher compression |
| Special Super Turbo‑Thrust | ’60‑’61 | 335 hp | Mechanical cams, high‑rise intake, tri‑power carbs |
| 409 Turbo‑Fire | ’61‑’65 | 360–425 hp | Larger bore/stroke, single & dual carb options, top of W series |