6L-161 Henry J / Corsair DeLuxe
1951–195480 hp @ 3800 rpm; 133 lb-ft @ 1600 rpm
Six-cylinder upgrade over the 134 four
Henry J 161 Supersonic Six enginePhoto: CZmarlin — Christopher Ziemnowicz · CC0 1.0
Kaiser-Frazer · Henry J Supersonic Six
Henry J 161 Supersonic Six
The 80-hp six-cylinder upgrade that gave the Henry J substantially better performance than the base four.
161
Cubic inches
The 161 six was the more desirable Henry J engine and became closely associated with the car's later hot-rod and drag-racing legacy, even though racers usually replaced it.
Key variants
All variants6L-161 Henry J / Corsair DeLuxeRelated Willys 161 family
Displacement
161 ci
Bore
3.125"
Stroke
3.5"
Years
1951–1954 Henry J era
Key Takeaway
The Henry J 161 was a Willys-family flathead six with a 3.125-inch bore and 3.50-inch stroke. It provided more smoothness and torque than the 134 four while preserving the same simple side-valve, single-carburetor philosophy.
Technical Specifications
- Compression
- 7.0:1 in 1951 Henry J specification
- Horsepower
- 80 hp @ 3800 rpm
- Torque
- 133 lb-ft @ 1600 rpm (factory Henry J shop manual)
- Architecture
- L-head inline six, Willys 161 family
- Block
- Cast iron
- Cylinder heads
- Cast iron
- Valvetrain
- Side-valve L-head
- Aspiration
- Naturally aspirated
- Fuel delivery
- Single-barrel carburetor
- Firing order
- 1-5-3-6-2-4
- Main bearings
- 4
The Henry J 161 was a Willys-family flathead six with a 3.125-inch bore and 3.50-inch stroke. It provided more smoothness and torque than the 134 four while preserving the same simple side-valve, single-carburetor philosophy.
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
- 6L-161 (factory Henry J shop-manual engine model designation)
- Casting numbers
- No single Kaiser-Frazer-specific 6L-161 block casting is treated as a universal identifier in the reviewed factory material; use the 6L-161 model designation, engine serial/stamp and application evidence together.
- Power rating
- Period brake horsepower / SAE gross-era rating
- Horsepower RPM
- 80 hp @ 3800 rpm
- Torque RPM
- 133 lb-ft @ 1600 rpm
Operating Specs
- Production notes
- The Henry J factory shop manual identifies the six as model 6L-161 and specifies 161 cid, 7.0:1 compression, 80 brake hp at 3800 rpm and 133 lb-ft at 1600 rpm.
Compatibility Notes
- The Henry J 161 is an L-head six; do not confuse it with the later/high-compression 161 F-head used in the Kaiser Darrin even though displacement is similar.
- Verify head type, engine serial/stamp, carburetor, front dress, mounts and transmission interface before ordering parts.
Notable Applications
Henry J DeluxeHenry J Corsair Deluxe
Strengths
- More power and smoothness than 134 four
- Compact six-cylinder packaging
- Simple serviceability
Weaknesses / Watch-outs
- Only 80 hp in early trim
- Flathead breathing
- Limited factory performance potential
Common Upgrades
- Ignition modernization
- Carburetor tuning
- Period exhaust upgrades
Racing History & Legacy
Like the 134, the stock Henry J 161 was not the engine behind the model’s later gasser fame. Henry J bodies became highly recognizable drag-racing shells because of their light weight and compact dimensions, but serious gassers typically used engine swaps; the stock 161’s significance is production history rather than a major factory racing program.
The 161 gave the Henry J more usable torque while preserving the car’s economy-car mission, and the same displacement family later appeared in the F-head form used by the Kaiser Darrin.
References & Image Credit
Engine image: CZmarlin — Christopher Ziemnowicz · CC0 1.0 · source
Hagerty — 1951 Henry J Deluxe specs
vehicle spec
Hemmings — Henry J Deluxe history
historical reference
Old Cars Weekly — Henry J engine history
historical reference
1951–1953 Henry J factory shop manual — engine data
factory service manual
NHRA — Henry J drag-racing history
motorsport history
Hot Rod — Henry J gasser history
motorsport history
Wikimedia Commons — 1951 Henry J 161 flathead-six engine
licensed media
Key Factory / Build Variants
Related Willys 161 family
early 1950sApplication dependent
Shared Willys engine-family roots; exact L-head/F-head application must be verified
Engineering Notes Worth Knowing
01
161 cu in / 2.6 L with 3.125 x 3.50-inch bore and stroke.
02
Cast-iron L-head inline-six.
03
Single-barrel carburetion.
04
Factory rating: 80 hp and 133 lb-ft.
History · context · related reading
The Story Behind Henry J 161 Supersonic Six
The 161 gave Henry J buyers a more usable six-cylinder option without abandoning the car's economy mission. It later became closely associated with the Henry J's hot-rod reputation, even though serious racers usually swapped in much larger engines.
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