What Is a Stroker Engine? Stroker Kits, Bore and Stroke Explained
A stroker engine is an engine fitted with a crankshaft that has a longer stroke than the original, so the pistons travel farther and the engine displaces more air and fuel on each revolution. More displacement usually means more torque and power, without changing the size of the block. A stroker kit is the matched set of parts that does it: the crankshaft, connecting rods and pistons.
Bore and stroke explained
Bore is the diameter of each cylinder. Stroke is the distance the piston travels from the bottom to the top of the cylinder, set by the crankshaft. Displacement for a V8 is:
Cubic inches = bore x bore x stroke x 0.7854 x 8
A small block Chevy with a 4.030″ bore and the 350’s 3.480″ stroke works out to about 355 cubic inches. With a 3.750″ stroke crankshaft in the same bore it becomes about 383 cubic inches, the classic 383 stroker. Our 383 stroker engine guide covers that build in detail.
Popular stroker engines
| Stroker | Base engine | Bore x stroke | Displacement |
|---|---|---|---|
| 383 Chevy | Small block Chevy 350 | 4.030″ x 3.750″ | about 383 ci |
| 347 Ford | Small block Ford 302 | 4.030″ x 3.400″ | about 347 ci |
| 408 Ford (Windsor) | Small block Ford 351W | 4.030″ x 4.000″ | about 408 ci |
| 632 Chevy | Big block Chevy | 4.600″ x 4.750″ | about 632 ci |
Pros and cons of a stroker
- Pros: more torque across the rev range and more power from the same external engine size, so it fits where the original engine did.
- Cons: a longer stroke raises piston speed at a given RPM. Clearances inside the block (rods to block and camshaft) have to be checked, and the parts must be matched: crank, rods, pistons and balance.
Forged vs cast crankshafts
Cast crankshafts are cheaper and fine for many street builds. Forged crankshafts are stronger and preferred for high power, high RPM or boost. Check what each kit or engine uses in its product description.
Stroker crate engines and kits we stock
- 383 stroker crate engines from BluePrint (436 and 445 HP versions, base to fully dressed EFI).
- 347 and 408 stroker crate engines from BluePrint: the 347 at 415 HP and the Windsor-based 408 at 450 HP.
- The BluePrint 632 big block Chevy, rated at 815 HP.
- Building your own? See Eagle rotating assemblies and engine blocks.
More reading: what is a blueprinted engine.
Frequently asked questions
Is a 383 stroker better than a 350?
A 383 has more displacement and torque than a 350 in the same-size block. The BluePrint 383 crate engines we sell are rated at 436 to 445 HP (the Quicksilver QS 383 circle-track engine at 400 HP), against 330 to 405 HP for our 350s, at a higher price.
What is in a stroker kit?
Typically a longer-stroke crankshaft, matching connecting rods and pistons, often with rings and bearings, and sometimes balanced as a set.
Does a stroker engine need a different block?
Usually not, which is the main appeal. The longer stroke fits in the original block, although some builds need minor clearancing.
Related: horsepower vs torque, long block vs short block, Chevy firing order, Ford firing order, liters to cubic inches, 427 engine, compression ratio.
Comments