Plymouth 426 Hemi Engine Specs

Bore, stroke, displacement and compression for all 2 Plymouth 426 Hemi engines, compared side by side. Plus rod ratio and head specs where published.

At a glance

Displacement	426 ci
Cylinders	8
Bore	4.250"
Stroke	3.750–3.800"
Compression	10.3:1
Advertised power	425 hp

Engines in this family

Engine	Displacement	Bore × Stroke	CR	HP
R	426 ci	4.25" × 3.75"	10.25:1	425
J	426 ci	4.25" × 3.8"	10.25:1	425

Factory cars with a 426 Hemi

• Dodge D-Series Pickup: 1964, 365 hp; 1965, 365 hp; 1966, 365 hp
• Dodge Coronet: 1965, 365 hp; 1966, 425 hp; 1967, 425 hp; 1968, 425 hp; 1969, 425 hp; 1970, 425 hp
• Plymouth Satellite: 1965, 365 hp; 1966, 425 hp; 1967, 425 hp
• Dodge Charger: 1966, 425 hp; 1967, 425 hp; 1968, 425 hp; 1969, 425 hp; 1970, 425 hp; 1971, 425 hp
• Plymouth GTX: 1967, 425 hp; 1968, 425 hp; 1969, 425 hp; 1970, 425 hp; 1971, 425 hp
• Plymouth Road Runner: 1968, 425 hp; 1969, 425 hp; 1970, 425 hp; 1971, 425 hp
• Dodge Challenger: 1970, 425 hp; 1971, 425 hp
• Plymouth Barracuda: 1970, 425 hp; 1971, 425 hp

What varies across the family

Every engine here shares a 4.25" bore; displacement varies by stroke alone, which is the signature of a family built on one block with different cranks.

All are oversquare — bore larger than stroke, which favours revs over low-end torque.

Each engine page carries rod ratio, mean piston speed, bore/stroke character and cylinder head specs where published, and links into the calculators with its dimensions already filled in.

← All Plymouth engines