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Nissan SR20 specs: 2.0L (121.9 ci) 4-cylinder, 86 x 86 mm (3.3858 x 3.3858 in) bore and stroke, 8.5:1 compression. Rated 205-250 hp. DOHC.
The Nissan SR20 is exactly square — 3.3858" bore and 3.3858" stroke are the same — which splits the difference between a high-revving layout and a torque layout. The 3.3858" stroke does not reach 4,000 ft/min of mean piston speed until about 7,100 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 30.5 ci (499 cc).
8.5:1 on aluminum heads is low by modern standards and generally happy on regular pump fuel.
It is one of 5 engines in the SR20 family, all of them 121.9 ci — the differences between them are in compression, heads and rating, not displacement. 4 factory variants share these dimensions, rated from 205 to 250 hp. Factory fitments include the Nissan Silvia S14, Nissan Silvia S15, Nissan Silvia S13 and 1 other.
| Displacement | 121.9 ci / 2 L |
|---|---|
| Bore | 3.3858" |
| Stroke | 3.3858" |
| Cylinders | 4 |
| Compression ratio | 8.5:1 |
| Bore/stroke ratio | 1 |
| Block material | cast iron |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 205–250 hp |
| Bore/stroke character | 1.000 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,386 ft/min — conservative for a street engine |
| Displacement per cylinder | 30.5 ci |
| Static compression | 8.5:1 — low by modern standards, generally happy on regular pump fuel |
Each link opens the calculator with this engine's specs already filled in.
These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
|---|---|---|
| — | 205 hp | SR20DET (Red Top), SR20DET (Black Top S13) |
| — | 220 hp | SR20DET (Black Top S14 Zenki) |
| — | 245 hp | SR20DET (Black Top S14 Kouki) |
| — | 250 hp | SR20DET (Black Top S15) |