Kaiser-Frazer 226 Supersonic Six enginePhoto: Unknown author · Public domain

Kaiser-Frazer · Continental 226 Supersonic

Kaiser-Frazer 226 Supersonic Six

The Continental-designed, Kaiser-Frazer-built flathead six that powered most full-size Kaiser and Frazer cars.

226.2

Cubic inches

The 226 was the core Kaiser-Frazer engine: Continental-designed, built by Kaiser-Frazer, and used across nearly the company's entire full-size passenger-car run.

Key variants

All variantsContinental-derived early 226Kaiser-built Supersonic 226

Displacement

226.2 ci

Bore

3.3125"

Stroke

4.375"

Years

1947–1955 U.S. passenger-car era

Key Takeaway

The 226 Supersonic used a Continental-derived cast-iron flathead six with a 3.3125-inch bore and 4.375-inch stroke. Kaiser-Frazer adapted the design for its own cars, relying on long-stroke torque and durability across most of its full-size lineup.

Technical Specifications

Compression: 7.3:1 in documented 1949 Frazer specification; later Kaiser tune varied by year
Horsepower: 112 hp @ 3600 rpm in 1949–50 Frazer specification; approximately 115–118 hp in later naturally aspirated Kaiser versions
Torque: 190 lb-ft @ 1400 rpm in documented 1949 Frazer specification
Architecture: L-head inline six
Block: Cast iron
Cylinder heads: Cast iron
Valvetrain: Side-valve L-head with solid lifters
Aspiration: Naturally aspirated
Fuel delivery: Carbureted
Firing order: 1-5-3-6-2-4
Main bearings: 4

Internal Specifications

Variant-specific values are labeled. Engine families that span multiple years or RPOs can have different heads, cams, induction and rotating parts, so the exact code/year always takes priority.

Identification & Output

Engine codes / RPO: L6-226 / 6L-226 (Willys/Kaiser service-manual designation for the 226-cid L-head six)
Casting numbers: Kaiser-built 1952–54 passenger-car 226s are identified by the cast 'Kaiser Supersonic' cylinder-head script in specialist restoration documentation; the reviewed source set does not establish one universal block casting number for all 1947–55 Kaiser-Frazer 226 applications.
Power rating: Period brake horsepower / SAE gross-era rating
Horsepower RPM: 112 hp @ 3600 rpm in documented 1949–50 Frazer specification; roughly 115–118 hp in later naturally aspirated Kaiser tune
Torque RPM: 190 lb-ft @ 1400 rpm in documented 1949 Frazer specification

Operating Specs

Production notes: Kaiser restoration documentation says Kaiser purchased rights to the Continental engine in late 1947 and redesigned it for power and reliability. Kaiser-built 1952–54 passenger-car examples carried 'Kaiser Supersonic' script cast into the head; the same basic 226 family later saw Willys/Jeep use.

Compatibility Notes

The Kaiser-Frazer parts cross-reference lists major service overlap with Jeep 226 applications, but car-specific head, induction, accessory, mount and transmission details still require verification.
Do not treat a later Willys/Jeep L6-226 calibration or serial prefix as automatically identical to a Kaiser passenger-car engine; tune and external equipment changed by application.

Notable Applications

Kaiser SpecialKaiser DeluxeKaiser Manhattan before superchargingFrazer StandardFrazer Manhattan

Strengths

Robust long-stroke torque
Four-main-bearing crank
Broad Kaiser-Frazer parts knowledge

Weaknesses / Watch-outs

Flathead breathing limits output
Long 4.38-inch stroke
Heavy for its power

Common Upgrades

Dual-carb period induction
Electronic ignition
Exhaust improvements

Racing History & Legacy

The naturally aspirated 226 Supersonic was primarily Kaiser-Frazer’s durable passenger-car powerplant rather than a dedicated works racing engine. Its performance story is more important as the foundation for the factory-supercharged 1954–55 Manhattan version than for a major sanctioned-racing campaign.

The 226 was the backbone of full-size Kaiser-Frazer power. Kaiser acquired rights to the Continental design, revised the crankshaft, compression and valve timing, and continued developing it into the factory-supercharged Manhattan engine.

References & Image Credit

Engine image: Unknown author · Public domain · source

Hemmings — Frazer 226 technical overview

technical reference

Hemmings — 1953 Kaiser 226 output

historical reference

Hemmings — 226.2 bore/stroke and 1949–50 Frazer output

technical reference

Kaiser Bill — 1951–53/1954–55 Kaiser restoration notes and 226 engine history

specialist restoration reference

Kaiser-Frazer parts cross-reference — 226 and 161 service-part interchange

specialist parts reference

Willys 1954–1960 factory service manual — L6-226 engine and firing order

factory service manual

Key Factory / Build Variants

Continental-derived early 226

1947–early Kaiser-Frazer era

Application/year dependent

Original Continental-rooted Kaiser-Frazer six

Kaiser-built Supersonic 226

1952–1955 U.S. passenger-car era

Approximately 115–118 hp naturally aspirated in later tune

Kaiser-redesigned production version with Supersonic head identification

Engineering Notes Worth Knowing

226.2 cu in / 3.7 L with 3.3125 x 4.375-inch bore and stroke.

Cast-iron L-head inline-six with four-main-bearing crank.

Carbureted and naturally aspirated.

Representative output: 112–118 hp and about 190 lb-ft depending year.

History · context · related reading

The Story Behind Kaiser-Frazer 226 Supersonic Six

The 226 was the workhorse of Kaiser-Frazer. It powered nearly the entire full-size passenger-car run and gave the company a dependable engine even though it never developed its own production V8.

TorqueList Garage Reference Series

See this engine inside the full Kaiser-Frazer reference catalog.

The same Engine Library data now powers a more detailed mobile-friendly catalog with technical specs, variants, engineering notes, history and related stories.