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Although Boxster, Cayman, and 911 models from 1997 through 2008 are a great value and wonderful cars, some current or future Porsche owners have chosen to avoid these models, even though the IMS can be addressed through preventative maintenance with the IMS Retrofit and IMS Solution. Other issues such as bore scoring have made these models less desirable, however a future-proofed M96 engine will provide a lifetime of reliable operation for these models.
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M96's successor, the 9A1 engine was introduced with the 2009 model year.
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What has changed? The 9A1 shares very little from its predecessor other than being horizontally opposed. And now that these cars are over ten years old, what have we learned?
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Although base Boxster and Cayman models retained port fuel injection, S and 997.2 models received direct injection. Fuel is injected directly into the combustion chamber at much higher pressures with direct injection, allowing for greater thermal efficiency increased compression ratios, with reduced emissions and improved fuel economy. But what matters most is the fact that these engines make more power.
As with other makes and models with direct injection, intake deposits are a real concern and can be addressed with services like walnut shell blasting which allows intake ports to be cleaned once the intake manifold is removed to gain access to intake ports. Fuel dilution is also a real concern with higher injection pressures allowing for increased fuel dilution as fuel makes its way past the piston rings. Lastly, intake valve guide wear as a result of lack of cooling and cleaning without port injection can occur.
Wear for high pressure fuel pumps, regardless of make and model, is a common issue requiring replacement due to failure. With the reduction of sulfur from our fuels and introduction of ethanol enriched fuels, reduced lubricity can cause fuel system issues. Using high octane non-ethanol fuels meeting the minimum octane requirement or Top Tier Fuels like Shell's V-Power are ways you can minimize issues, as well as use of additives like
Driven Injector Defender at every fill up.
Shorter oil change intervals of six months or 5,000 miles with an oil designed to address direct injection issues like
Driven DI40 is recommended.
DI40 has increased HTHS viscosity that fights fuel dilution. Direct injected engines can also suffer from a phenomenon called LSPI, or low speed pre-ignition, which Driven's unique formulation addresses and factory approved A40 oils do not.
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Redesigned Integrated Dry Sump
with PWM Variable-Demand Oil Pump
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Anyone who has tracked a car with the M96 engine knows of oil starvation issues associated with the prior generation of integrated dry sump, which is nothing more than a conventional wet sump engine with additional scavenge pumps to return oil to sump. One of the strongest areas of the 9A1 engine is the pulse-width modulated variable demand oil pump that is controlled by the DME, ensuring that regardless of oil temperature, the engine has sufficient oil pressure for whatever loads and speeds it is seeing. Beyond this changed, improved baffling and scavenging ensures there is always oil in the sump to feed the oil pickup.
987.2, 997.2, and later models with the 9A1 engine (and 9A2) can see extremely high oil temperatures on track, especially those models with PDK and that do not have a center radiator fitted. Adding a
2.5 quart deep sump adds enough volume to lower high oil temperatures on track by 30-40 degrees F.
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The M96 engine utilizes an intermediate shaft, off of which chains run that drive the camshafts. This allows the camshafts to be driven slower than crank rotation speed. The 9A1 engine now drives the chains from the front of the crankshaft, as well as the oil pump, all at full crankshaft speed, requiring higher quality chains that can handle the increased loads and speeds.
High mileage or engines subjected to many hours of track abuse have shown increasing cam timing deviation due to stretched chains. Timing chain stretch and wear is an issue made worse by soot formation in dirty engine oil, especially with long drain intervals, which can also be addressed with shorter drain intervals.
The change to a two piece crankcase with integral main bearing saddles also allowed for the elimination of the crankshaft cradle which in the prior generation's M96 engine held the main bearing saddles and oil squirters for the cylinder bores.
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The M96 engine's crankcase was manufactured by Kolbenschmidt utilizing their Lokasil process (later using Lokasil II and III variants), which uses a freeze cast cylinder liner insert that contains the silicon matrix which makes up the wear surface of the bore. During the casting process, the aluminum used to cast the block infiltrates the porous liner insert. The cylinders do not have any plating or coating on the bores, requiring use of special piston coatings to reduce wear. Cylinder issues such as bore scoring, d-chunk, or slipped sleeve failures can occur with this generation of engine, so Porsche chose to start with a clean slate with the 9A1.
The 9A1 engine features a closed deck for added strength and rigidity and is cast out of Alusil. Porsche is no stranger to Alusil, having used this process for the 944 and 928 and more recently the Cayenne S and Turbo as well as for aircooled engines including the 2.7 and 3.0SC. Like with Lokasil, the bores do not have any coating, relying on piston skirt coatings to reduce wear. Alusil receives a special etching or mechanical activation process that exposes the silicon particles that serve as the load carrying wear surface of the aluminum bores.
Care must be taken to limit engine RPMs and reduce throttle input when the 9A1 engine is cold, especially in colder climates, to allow for the engine to warm up and increase the tight piston to cylinder clearances found in these engines. The same goes for M96 and M97 models through 2008 with forged pistons as a precaution to reduce piston wear that can develop into bore scoring.
As with all hypereutectic cylinder bore technologies, cylinder scoring can occur, even in the 9A1 engine, but these failures as of now are the exception, not the rule. Available research would seem to indicate that oils with higher HTHS viscosities and moly friction modifiers may provide additional protection for any engine with hypereutectic bores.
The block shown above has been upgraded with Nickies Lite plated cylinder bores, which resolves cylinder wear issues with these models at time of overhaul.
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What does the future hold?
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Porsche has turned to Oerlikon Metco's SUMEbore technology in its newest engines, starting first with the 918 Sypder, allowing them to push the limits of performance with exceptional low wear characteristics. In the past, Nikasil plating was Porsche's go to for maximum performance and extremely low wear, but SUMEbore is much more eco-friendly. We're keeping a close eye on this emerging technology, but we are hopeful that it will be a viable alternative to Nikasil in the future with its successful deployment by many OEMs including Nissan and Ford.
Oil technology is changing with new standards like Porsche's C40 to address soot and LSPI issues and current research is working towards finding new additive technologies like Ionic Liquids and improving existing ones, like Moly friction modifiers, to help reduce emissions and increase fuel economy while reducing wear and improve the longevity of automotive engine components, including hypereutectic cylinder bores. Tailpipe soot emissions are the latest target of European regulation, requiring gasoline particulate filters to be fitted to Porsche's newest models starting now with some 2019 model year vehicles.
Lastly, many manufactures have turned to hybrid direct and port injection fuel systems to combat intake guide wear and intake port deposits and optimize fuel delivery for varying engine speeds and loads, so we expect to see port fuel injection slowly finding its way back onto direct injected engines.
Emerging technologies makes modern vehicles perform better, more efficiently, and safer to operate, but these systems will make these newest models ever more difficult to work on and costly to own, making older ones including the 1997-2008 models with the M96 engine ever so more attractive to those who see the appeal in these much simpler and analog models.
Charles Navarro
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125 Gladiolus St. | PO Box 401 | Momence, IL 60954 | Phone (815) 472-2939 Fax (413) 280-9041
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All logos and trademarks used for product identification purposes only.Porsche ® 356 ® , 911 ® , 912 ® , 914 ®, Boxster®, Cayman®, Panamera® and Cayenne® are registered trademarks of Dr. Ing. H.c. F. Porsche AG.
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