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Mercedes-Benz M177 specs: 4.0L (243 ci) 8-cylinder, 83 x 92 mm (3.2677 x 3.6220 in) bore and stroke, 8.6:1 compression. Rated 469-603 hp, 2015–2026.
The Mercedes-Benz M177 is undersquare — the 3.622" stroke exceeds the 3.2677" bore by 9.8% — a layout that trades peak RPM for leverage and torque low in the range. 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 30.4 ci (498 cc).
8.6:1 is low by modern standards and generally happy on regular pump fuel.
It is one of 3 engines in the Mercedes-Benz 243ci family, all of them 243 ci — the differences between them are in compression, heads and rating, not displacement. 28 factory variants share these dimensions, rated from 469 to 603 hp across 2015–2026.
| Displacement | 243 ci / 4 L |
|---|---|
| Bore | 3.2677" |
| Stroke | 3.622" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 8.6:1 |
| Bore/stroke ratio | 0.902 |
| Fuel type | gas |
|---|---|
| Advertised HP | 469–603 hp |
| Years | 2015–2026 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 2018 | M177 net | 603 @ 5750-6500 | 627 lb-ft @ 2500-4500 | 8.6:1 |
| 2019 | M177 net | 603 @ 5750-6500 | 627 lb-ft @ 2500-4500 | 8.6:1 |
| 2020 | M177 net | 603 @ 5750-6500 | 627 lb-ft @ 2500-4500 | 8.6:1 |
| 2021 | M177 net | 603 @ 5750-6500 | 627 lb-ft @ 2500-4500 | 8.6:1 |
| 2023 | M177 net | 603 @ 5750-6500 | 627 lb-ft @ 2500-4500 | 8.6:1 |
Factory specification sheet.
| Bore/stroke character | 0.902 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,622 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 30.4 ci |
| Static compression | 8.6:1 — 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 |
|---|---|---|
| 2015 | — | M177 |
| 2016 | — | M177 |
| 2017 | — | M177 |
| 2018 | — | M177 |
| 2018 | 603 hp | M177 |
| 2019 | — | M177 |
| 2019 | 577 hp | M177 |
| 2019 | 603 hp | M177 |
| 2020 | — | M177 |
| 2020 | 577 hp | M177 |
| 2020 | 603 hp | M177 |
| 2021 | — | M177 |
| 2021 | 577 hp | M177 |
| 2021 | 603 hp | M177 |
| 2022 | — | M177 |
| 2022 | 469 hp | M177 |
| 2022 | 577 hp | M177 |
| 2023 | — | M177 |
| 2023 | 469 hp | M177 |
| 2023 | 577 hp | M177 |
| 2023 | 603 hp | M177 |
| 2024 | 469 hp | M177 |
| 2024 | 577 hp | M177 |
| 2025 | 469 hp | M177 |
| 2025 | 577 hp | M177 |
| 2026 | — | M177 |
| 2026 | 469 hp | M177 |
| 2026 | 577 hp | M177 |
5 factory vehicles, 2015–2026. Each year opens that model's engine table.