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Cadillac L26 specs: 300 ci (4.9L) 8-cylinder, 3.622 x 3.622 in (92 x 92 mm) bore and stroke, 9.5:1 compression. Rated 200 hp, 1991–1995.
The Cadillac HT4100 (L26) is exactly square — 3.622" bore and 3.622" stroke are the same — which splits the difference between a high-revving layout and a torque layout. The 3.622" stroke puts mean piston speed at 4,000 ft/min around 6,650 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 37.5 ci (615 cc).
9.5:1 on iron heads is in the range that usually runs on pump premium; iron holds heat, so treat it as the less forgiving side of that range.
It is one of 8 engines in the HT4100 family, the largest at 300 ci. 6 factory variants share these dimensions, rated at 200 hp across 1991–1995.
| Displacement | 300 ci / 4.9 L |
|---|---|
| Bore | 3.622" |
| Stroke | 3.622" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 9.5:1 * |
| Bore/stroke ratio | 1 |
* Compression ratio from a single source; not yet cross-verified.
| Block material | aluminum |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 200 hp |
| Years | 1991–1995 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 1991 | L26 net | 200 | 275 lb-ft | — |
Factory specification sheet.
| Bore/stroke character | 1.000 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,622 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 37.5 ci |
| Static compression | 9.5:1 — in the range that usually runs on pump premium |
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 |
|---|---|---|
| 1991 | — | L26 |
| 1991 | 200 hp | L26 |
| 1992 | 200 hp | L26 |
| 1993 | 200 hp | L26 |
| 1994 | 200 hp | L26 |
| 1995 | 200 hp | L26 |
3 factory vehicles, 1991–1995. Each year opens that model's engine table.