What is Cylinder Bore Scoring in Porsche Boxster, Cayman, and 911 Engines?

Porsche cylinder bore scoring occurs when there is a breakdown of the Al-Si cylinder system resulting in physical damage to the cylinder walls and piston skirts, resulting in significant oil consumption, increased engine noise, and eventual engine failure. This can occur to any engine with a hypereutectic aluminum engine block like the Lokasil and Alusil engine blocks used by Porsche and other manufacturers.

Which Porsche 911 engines suffer from cylinder bore scoring?

Regardless of model year, all Porsche 911 engines from 1999 to 2008 are susceptible to cylinder bore scoring, with some years being more problematic than others:

• 1999 Porsche 911 996.1 – 3.4 Liter M96.01/M96.02/M96.04 engines
• 2000 Porsche 911 996.1 – 3.4 Liter M96.01/M96.02/M96.04 engines
• 2001 Porsche 911 996.1 – 3.4 Liter M96.01/M96.02/M96.04 engines
• 2002 Porsche 911 996.2 – 3.6 Liter M96.03 engine
• 2003 Porsche 911 996.2 – 3.6 Liter M96.03 engine
• 2004 Porsche 911 996.2 – 3.6 Liter M96.03 engine
• 2005 Porsche 911 996.2 – 3.6 Liter M96.05 engine
• 2005 Porsche 911 997.1 – 3.6 Liter M96.05 & 3.8 Liter M97.01 engines
• 2006 Porsche 911 997.1 – 3.6 Liter M96.05 & 3.8 Liter M97.01 engines
• 2007 Porsche 911 997.1 – 3.6 Liter M96.05 & 3.8 Liter M97.01 engines
• 2008 Porsche 911 997.1 – 3.6 Liter M96.05 & 3.8 Liter M97.01 engines

All base and S models can suffer from cylinder bore scoring. The most problematic engines for cylinder bore scoring at the 3.6 and 3.8 engines used in Porsche 911 996 and 997 models, however the 3.4 liter also can suffer from cylinder bore scoring. The longer stroke crankshaft used in the 3.6 and 3.8 engine coupled with the fact that the pistons comes out of the bore approximately 7mm (vs 2mm on the 3.4 engine) likely also contribute to this issue. Regardless of which model and engine you have, the cost of cylinder bore scoring repair and engine rebuild for Porsche 911 996 and 997 engines is similar.

Which Porsche Boxster and Cayman engines suffer from cylinder bore scoring?

Like with the Porsche 911, certain years of Porsche Boxster and Cayman engines can also suffer from cylinder bore scoring:

• 2006 Porsche Cayman 987.1 – 3.4 Liter M97.21 engine
• 2007 Porsche Cayman 987.1 – 3.4 Liter M97.21 engine
• 2007 Porsche Boxster 987.1 – 3.4 Liter M97.21 engine
• 2008 Porsche Cayman 987.1 – 3.4 Liter M97.21 engine
• 2008 Porsche Boxster 987.1 – 3.4 Liter M97.21 and M97.22 engines

Unlike the base and S Porsche 911 996 and 997 models, the base 2.5 and 2.7 engines used in Porsche Boxster models and the base 2.7 engine used in the Porsche Cayman do not often suffer from cylinder bore scoring. Likewise, cylinder bore scoring in the Boxster S 3.2 engine also is not very common. We believe attribute this to the fact that the piston is cast and uses an iron clad plating on the piston which appears to be more durable than the iron clad coating used in the 3.4, 3.6, and 3.8 liter engines which received a forged piston. We also believe the cast piston’s expansion rate being less than a forged piston also contributes to the durability of the 2.5, 2.7, and 3.2 liter engines.

Where can I learn more about Porsche Cylinder Bore Scoring?

For those of you who are Porsche Club of America members, PCA published an excellent article written by Carl Spencer, Bore Score and Seven Years Ago, in the February 2019 issue of Panorama. This is a great read for anyone concerned about or experiencing cylinder bore scoring and how to deal with the problem, where Carl Spencer explains the steps he took when his 997 suffered this expensive failure.

The four-part YouTube series from the Porsche Club of America on Porsche Cylinder Bore Scoring covers the following topics:

• What is Porsche Cylinder Bore Scoring
• What Causes Porsche Cylinder Bore Scoring
• How do you Prevent Porsche Cylinder Bore Scoring
• How do you Fix Porsche Cylinder Bore Scoring

Information with regards to the best practices on how to prevent cylinder bore scoring in Porsche engines is a helpful to all owners of Porsche Boxster, Cayman, or 911 models from 1997 on up (until Porsche went with SUMEbore in the 718 and 991.2 and later sports car engines). Many of these recommendations also apply to engines that utilize Alusil or similar hypereutectic aluminum engine blocks.

If you own a Porsche Boxster, Cayman, or 911 996 or 997 and you are unsure if your engine might be suffering from cylinder bore scoring, bore scoping your Porsche engine’s cylinder bores for scoring is usually the best way to identify if your engine is suffering from this issue. Porsche engines with cylinder bore scoring will make a ticking noise that is often misdiagnosed as bad lifters, making this the most common symptom besides sooty tail pipes and increased oil consumption that accompanies this issue.

A research paper published in 2019 titled “Understanding Bore Scoring in Al-Si Cyilnder Systems” discusses Alusil and Lokasil cylinder technologies as well as Porsche Cylinder Bore Scoring in great detail. This is a must read for anyone wanting to learn everything about Cylinder Bore Scoring.

The following three videos from Total Seal discuss cylinder bore scoring in engines with Lokasil or Alusil engine blocks including how to identify the issue and what steps can be taken to prevent it.

Flat 6 Innovations in conjunction withRennvision and The Knowledge Gruppe has put out many videos on YouTube on the topic of cylinder bore scoring and how it affects Porsche Boxster, Cayman, and 911 models with the M96 and M97 engines.Check out more videos on Porshce Cylinder Bore Scoring now.

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