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Acura B18A1 specs: 1.8L (111.9 ci) 4-cylinder, 81 x 89 mm (3.1890 x 3.5039 in) bore and stroke, 9.2:1 compression. Rated 130-140 hp, 1990–1993.
The Acura B18A1 is undersquare — the 3.5039" stroke exceeds the 3.189" bore by 9.0% — a layout that trades peak RPM for leverage and torque low in the range. The 3.5039" stroke puts mean piston speed at 4,000 ft/min around 6,850 RPM, which is where a production bottom end is generally considered at its limit. Each of the 4 cylinders displaces 28.0 ci (458 cc).
9.2:1 on aluminum heads is low by modern standards and generally happy on regular pump fuel.
It is one of 15 engines in the Honda B-series family, sitting between the 97 ci and 121.8 ci members. 4 factory variants share these dimensions, rated from 130 to 140 hp across 1990–1993.
| Displacement | 111.9 ci / 1.8 L |
|---|---|
| Bore | 3.189" |
| Stroke | 3.5039" |
| Cylinders | 4 |
| Configuration | I4 |
| Compression ratio | 9.2:1 |
| Bore/stroke ratio | 0.91 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Firing order | 1-3-4-2 |
| Advertised HP | 130–140 hp |
| Years | 1990–1993 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 1990 | B18A1 net | 130 @ 6000 | 121 lb-ft @ 5000 | 9.2:1 |
| 1991 | B18A1 net | 130 @ 6000 | 121 lb-ft @ 5000 | 9.2:1 |
| 1992 | B18A1 net | 140 @ 6300 | 126 lb-ft @ 5000 | 9.2:1 |
| 1993 | B18A1 net | 140 @ 6300 | 126 lb-ft @ 5000 | 9.2:1 |
Factory specification sheet.
| Bore/stroke character | 0.910 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,504 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 28.0 ci |
| Static compression | 9.2:1 — 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 |
|---|---|---|
| 1990 | 130 hp | B18A1 |
| 1991 | 130 hp | B18A1 |
| 1992 | 140 hp | B18A1 |
| 1993 | 140 hp | B18A1 |
1 factory vehicle, 1990–1993. Each year opens that model's engine table.