The 3.4-liter boxer Porsche M97.21 engine was produced by the concern from 2005 to 2009 and was installed on advanced modifications of the Cayman S coupe or Boxster S cabriolet in the back of 987. There was a slightly more powerful version of this power unit under its M97.22 index.
Engines of M97-line: M97.20, M97.21.
Specifications
| Production years | 2005-2009 |
| Displacement, cc | 3387 |
| Fuel system | distributed injection |
| Power output, hp | 295 |
| Torque output, Nm | 340 |
| Cylinder block | aluminum H6 |
| Block head | aluminum 24v |
| Cylinder bore, mm | 96 |
| Piston stroke, mm | 78 |
| Compression ratio | 11.1 |
| Features | no |
| Hydraulic lifters | yes |
| Timing drive | chain |
| Phase regulator | VarioCam Plus |
| Turbocharging | no |
| Recommended engine oil | 5W-40 |
| Engine oil capacity, liter | 7.75 |
| Fuel type | petrol |
| Euro standards | EURO 4 |
| Fuel consumption, L/100 km (for Porsche Cayman S 2008) — city — highway — combined |
15.3 7.8 10.6 |
| Engine lifespan, km | ~240 000 |
| Weight, kg | 191 |
The engine was installed on:
- Porsche Boxster 2 (987) in 2006 – 2009;
- Porsche Cayman 1 (987) in 2005 – 2009.
Disadvantages of the Porsche M97.21 engine
- The most famous problem of the M97 family of units is seizures in the cylinders;
- These motors did not escape the massive problem with the intermediate shaft bearing;
- Also, there are very high requirements for lubrication and often turns the liners;
- By a run of 150,000 km, it usually requires replacing the timing chain;
- The weak point of the engine is its cooling system and in particular the water pump.
The two biggest issues with this engine are cylinder bore scoring and the intermediate shaft bearing.
The IMS can be addressed by simply removing the grease seal off the original bearing since the bearing cannot be replaced on these models without complete engine disassembly.
The Porsche cylinder bore scoring issue is the #1 problem. Bore scoping an engine to check for this issue is a must. If all checks out, there are numerous things you can do to prevent this issue starting with running Driven DT40 engine oil as the high levels of moly are needed to protect the cylinder bores from scoring.
LN Engineering is the foremost expert in the US on these engines and offers recommendations for addressing the IMS and bore scoring issues.
https://www.LNengineering.com