Cylinder Bore Scoring - Part 3: How To Prevent it? - with Lake Speed Jr.

Описание: In this final installment on cylinder bore scoring, Lake Speed Jr. from Total Seal Piston rings and Charles Navarro from LN Engineering discuss how to reduce the likelihood of cylinder bore scoring in water-cooled Porsche Boxster, Cayman, and 911 engines as well as many other engines with hypereutectic aluminum Alusil or Lokasil engine blocks.

We all know how important surface finish is to the proper function of the piston/ring/cylinder system and it is this surface finish that dictates the bearing surface curve, or the ability of the surface to support a load, when properly lubricated.

Remember the 4 R’s - there right oil, in the right place, in the right amount, at the right time. If you don’t get all 4 right, wear or failure can occur.

So what is the right oil? Ever since the early 2000s, manufacturers have been pushing for improved fuel economy as mandated by CAFE, better known as the corporate average fuel economy requirements, which results in fines to be paid by manufacturers who don’t meet this government mandated requirements. Thinner and thinner oils provide manufacturers an easy way to improve fuel economy, but at what cost? Increased wear.

Oils have also been reformulated to low or even no SAPS (sulfated ash, phosphorus and sulfur) to extend the life of emissions protection devices such as catalytic converters and particulate filters, as again, these devices are mandated to have much longer warranties by our governments than the typical bumper to bumper or powertrain warranties most vehicles have.

This means that most manufacturer recommended lubricants have lower anti-wear additives and reduced HTHS (high temperature high sheer) viscosities which directly affect the formation of anti-wear films and the thickness of oil film that protects internal engine components. Where this might not immediately cause a problem, over time, the longevity of an engine can and often is affected negatively by these oils leading to failures outside of the warranty period.

For years we have recommended simply using a 5w40 rather than a 0w40 can sometimes yield as high as a 10 percent increase in HTHS viscosity and improve the shear stability of oils. We have also recommended uses of a full-SAPS or mid-SAPS oil where possible to reduce wear, but as OEM oil requirements change, it becomes increasingly hard to find oils that meet these requirements as seen with Porsche Classic releasing oils for 996 and earlier models in higher viscosities and with increased levels of anti-wear additives.

But don’t take our word for it. Like we’ve mentioned in previous newsletters, used oil analysis can be used to evaluate how well your engine is wearing as well as if your oil is doing a good job protecting your engine.

So specifically for a Porsche engine with Alusil or Lokasil bores, using an oil with higher HTHS viscosity with added molybdenum (moly) is something that can help with slowing down the ultra-mild wear regime for Al-Si (aluminum silicon) cylinder systems. Popular with many is the LM Ceratec additive which boosts moly content, but using Driven DT40 or DI40 oils provides a fully-formulated oil that doesn’t require additional additives that typical A40 and C40 oils don’t have anywhere near the concentrations that Driven’s oils have.

ZDDP alone won’t reduce wear as the Zn and P can’t bond to the aluminum. That’s where the moly comes in. Moly can form “glassy plates” on any surface in the engine and is activated by temperature and pressure. This tribofilm is what can slow down the wear in Alusil and Lokasil engines along with the increased film strength provided by Driven DT40 and DI40 oils.

Another issue we find with many engines that have suffered from bore scoring are those cylinders that have scored often have bad injectors. Dirty or leaky injectors can wash the cylinder bore down. Remember, fuel is a solvent, not a lubricant. Using a fuel system cleaner with PEA (polyetheramine) provides the strongest possible cleaning agent to keep your injectors clean. Ethanol enriched fuels are known to cause corrosive wear, so a fuel additive that also provides protection from ethanol corrosion is warranted.

If you haven’t watched it already, be sure to check out our YouTube videos with Tony Callas from Callas Rennsport on Porsche Engine Diagnostics including video on the topics of Modern Fuels and Maintenance, Vacuum Leaks, Manometer and Smoke Testing, and finally, Fuel Trims. These videos provide additional information pertinent to keeping your engine running correctly which goes a long way to reducing the chances of your Porsche engine suffering from cylinder bore scoring.