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Audi 25 I5 Tfsi Ea855evo specs: 2.5L (152.6 ci) 5-cylinder, 82.5 x 92.8 mm (3.2480 x 3.6535 in) bore and stroke, 10:1 compression. Rated 400 hp. DOHC.
The Audi 25 I5 Tfsi Ea855evo is undersquare — the 3.6535" stroke exceeds the 3.248" bore by 11.1% — a layout that trades peak RPM for leverage and torque low in the range. The 3.6535" stroke puts mean piston speed at 4,000 ft/min around 6,550 RPM, which is where a production bottom end is generally considered at its limit. Each of the 5 cylinders displaces 30.5 ci (500 cc).
10:1 on aluminum heads is in the range that usually runs on pump premium; aluminum sheds heat faster than iron, which makes the same number a little more forgiving.
It is one of 3 engines in the EA855 evo family, the largest at 152.6 ci. Factory fitments include the Audi TT RS (FV), Audi RS3 (8V), Audi RS Q3 (F3).
| Displacement | 152.6 ci / 2.5 L |
|---|---|
| Bore | 3.248" |
| Stroke | 3.6535" |
| Cylinders | 5 |
| Compression ratio | 10:1 |
| Bore/stroke ratio | 0.889 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 400 hp |
| Bore/stroke character | 0.889 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,654 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 30.5 ci |
| Static compression | 10:1 — in the range that usually runs on pump premium |
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