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Mercury B6 specs: 98 ci (1.6L) 4-cylinder, 3.071 x 3.291 in (78 x 83.6 mm) bore and stroke, 9.4:1 compression. Rated 100 hp, 1991–1994.
The Mercury 98ci (B6) is undersquare — the 3.2913" stroke exceeds the 3.0709" bore by 6.7% — a layout that trades peak RPM for leverage and torque low in the range. The 3.2913" stroke does not reach 4,000 ft/min of mean piston speed until about 7,300 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 24.5 ci (401 cc).
9.4:1 is low by modern standards and generally happy on regular pump fuel.
It is one of 2 engines in the Mercury 98ci family, all of them 98 ci — the differences between them are in compression, heads and rating, not displacement. 4 factory variants share these dimensions, rated at 100 hp across 1991–1994.
| Displacement | 98 ci / 1.6 L |
|---|---|
| Bore | 3.0709" |
| Stroke | 3.2913" |
| Cylinders | 4 |
| Configuration | I4 |
| Compression ratio | 9.4:1 |
| Bore/stroke ratio | 0.933 |
| Fuel type | gas |
|---|---|
| Advertised HP | 100 hp |
| Years | 1991–1994 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 1991 | net | 100 @ 5750 | 95 lb-ft @ 5500 | 9.4:1 |
| 1992 | net | 100 @ 5750 | 95 lb-ft @ 5500 | 9.4:1 |
| 1994 | net | 100 @ 5750 | 95 lb-ft @ 5500 | 9.4:1 |
Factory specification sheet.
| Bore/stroke character | 0.933 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,291 ft/min — conservative for a street engine |
| Displacement per cylinder | 24.5 ci |
| Static compression | 9.4:1 — 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 |
|---|---|---|
| 1991 | 100 hp | B6 |
| 1992 | 100 hp | B6 |
| 1993 | 100 hp | B6 |
| 1994 | 100 hp | B6 |
1 factory vehicle, 1991–1994. Each year opens that model's engine table.