My Porsche engine has scored bores. What can I do?
Unfortunately, many Boxster, Cayman, 911, Cayenne, Panamera, and Macan engines with Alusil or Lokasil engine blocks will suffer cylinder bore scoring. The Porsche engines we most commonly see with cylinder bore scoring that are sent to us for repair include the 3.6 and 3.8 Porsche 911 996 and 997 engines as well as with the 3.4 engine used in Cayman S and late Boxster S models.
Often, customers are told that they have bad lifters and that is the source of the tapping or ticking noise their engine is making. However, in most cases, that noise has nothing to do with your lifters and is in fact piston slap caused by excessive piston to cylinder clearance, a key indicator of scored bores, as well as having one sooty tail pipe and elevated wear metal levels in your Porsche’s engine oil. (Read more about this and other M96 and M97 engine problems and failures) As bore scoring progresses, oil consumption will increase as ring seal is compromised. For reference, a healthy factory M96 or M97 engine with a stock AOS should have a manometer reading of 4–6 inches of water column.
A diagnosis of scored bores doesn’t immediately mean your engine is dead. We see more and more engines being identified with bore scoring before symptoms have even manifested. This frequently happens when engines are bore scoped as part of the IMS pre-qualification procedure and through the use of used oil analysis to track iron, silicon, and aluminum wear levels in your Porsche’s engine oil.
We’ve seen many owners nurse an engine by switching to a thicker viscosity oil like Driven’s FR50 5w50 that also has increased moly levels allowing them to continue to drive their cars for months or even years until the symptoms become bad enough to require an engine rebuild or replacement as long as you don’t have any underlying conditions like a bad fuel injector or vacuum leak that is making the problem worse.
Where can I learn more about cylinder bore scoring in Porsche engines?
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 an expensive failure.
We’ve recently put together what we feel is very helpful information with regards to the best practices to help prevent cylinder bore scoring in Porsche engines which is a must read if you own a Porsche Boxster, Cayman, or 911 engine from 1997 on up (until Porsche went with SUMEbore in the 718 and 991.2 and later sports car engines). Check out LN Engineering’s How to Prevent Bore Scoring now.
Flat 6 Innovations in conjunction with Rennvision 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 Rennvisions playlist including all their videos on bore scoring now.
Last but not least, Charles Navarro published a research paper in 2019 titled “Understanding Bore Scoring in Al-Si Cyilnder Systems” discussing Alusil and Lokasil cylinder technologies as well as bore scoring in great detail. This is a must read for anyone wanting to know why bore scoring occurs in the first place.
Should I rebuild or replace my Porsche engine?
Although Porsche does offer engine shortblocks from the factory for Boxster, Cayman, and 911 models, these replacements do not address any of the inherent flaws associated with the factory Lokasil and Alusil cylinders and still require your shop to pull your existing cylinder heads, have them rebuilt, and then finish assembly of the engine to make it into a complete longblock. That said, for the same price, you can get additional value by rebuilding your existing engine rather than replacing it with another one from the factory. One such option is to use LN Engineering’s Nickies.
It is equally important that the most common trouble items are taken care of when rebuilding any M96 or M97 engine. Be sure to take a look at our article covering Porsche M96/M97 Engine Failures so that you can educate yourself with what is required to correctly overhaul and upgrade these engines. Beware there are many shops out there advertising rebuilt engines that don’t address any of the inherent issues with these engines.
Who can rebuild my Porsche engine?
The first step would be to find a shop that is familiar with rebuilding the M96 or M97 engine unless you decide to tackle the rebuild yourself. A good resource would be one of the many IMS Solution Certified Installers, as all of them have completed hands on training with Jake Raby at The Knowledge Gruppe.
If your shop doesn’t can’t offer you a rebuilt engine, RND Engines offers stock replacement M96/M97 Porsche long block engine rebuilds available exclusively through one of our Certified Installers and Flat 6 Innovations offers performance Porsche engine rebuilds through their own national network of installers.
Alternatively, if you choose to rebuild the engine yourself, check out Rennvision’s Focus On: M9X Engine Assembly DVD series. This should be the first thing you purchase and watch before taking the next step. You might also want to check out their Porsche Torque Spec Book and M9X Engine Assembly Workbook as both enthusiasts and professionals alike will find these resource immensely valuable when it comes time to reassemble the engine.
What are my options for rebuilding the M96 or M97 engine in my Porsche Boxster, Cayman, or 911?
Once you’ve chosen who is going to do the rebuild, the first step is to drop the engine and disassemble it. The engine block would then be shipped to us for our Nickies sleeving process. To make this easy, LN offers a pre-paid block shipping option where we ship you a custom box with molded inserts to ensure your case halves doesn’t get damaged in transit.
We machine every block for Nickies sleeves which replaces the cast-in Lokasil liner with a billet aluminum nickel silicon carbide plated bores. At the same time, we increase the bore size which allow for an increase in displacement and performance. We include matching JE, CP, or Mahle Motorsports pistons. Here is what we can do:
Where some other shops might offer slightly larger options using steel sleeves, our aluminum Nickies sleeves keep the engine running cooler and the NSC-plated bores, like those coated with Nikasil, reduce friction, all resulting in more horsepower through increased efficiency.
During the reconditioning process, the block deck gets surface ground and depending on how much is required to straighten the case, custom MLS head gaskets in the correct thickness are provided.
What do I need to do about IMS bearing while rebuilding my engine?
While the engine is apart, addressing the IMS issue is also a must. LN Engineering offers an intermediate shaft reconditioning service. This allows us to inspect the bearing housing bore for runout and also to pin the main drive sprocket, which can slip and cause a failure. We will also fit an IMS Retrofit or IMS Solution depending on what replacement ims bearing you want to go with. If your engine has suffered scored bores and was already fitted with an IMS Retrofit, the bearing should be replaced at time of rebuild. However, if your engine was fitted with an IMS Solution, you should be able to reuse it during the reassembly process.
What upgrades are available for my Porsche engine?
For a street engine, we would also recommend a 160F low temperature thermostat to help keep the engine cool and ARP rod bolts to replace the weak factory rod bolts. This provides a solid and reliable foundation for a reliable engine for your Porsche Boxster, Cayman, or 911.
If you ever plan on autocrossing or tracking your Porsche, additional upgrades need to be made to address other weaknesses inherent to the M96/M97 engine. These upgrades include:
Coated Connecting Rod and Main Bearings
ARP Crankshaft Carrier and Cylinder Head Bolts
By replacing the above components during your engine rebuild, you are addressing the known issues associated with the Porsche M96 and M97 engine used in 1997–2008 Porsche Boxster, Cayman, and 911 models and will have a track ready engine that should give you years of reliable service with proper maintenance.
Is an engine rebuild kit available for my Porsche engine?
Yes! To simplify the reassembly process, LN Engineering offers engine rebuild kits for Porsche M96 and M97 engines including M96.01, M96.02, M96.04, M96.03, M96.05, M97.01, and M97.21 engine designations with everything we recommend replacing. We can also assist with cylinder head rebuilding and porting or anything else you might need when it comes to rebuilding your Porsche’s engine.
Above our standard Porsche engine rebuild kits, the RND Premium and Deluxe Engine Kits also include many more items that are highly recommended to be changed out rather than reused. Components that are normally reused and not included in these kits should be evaluated, qualified, and replaced if necessary.
How do you recondition your Porsche crankshaft and M96/M97 crankshaft carrier/cradle?
Assuming your engine did not suffer a catastrophic failure, there is little to be done to the crankshaft and carrier. If there is wear or damage to the crankshaft, we recommend replacing both the crankshaft and carrier as a matched set. We only use Genuine Porsche bearings which are available only in standard size, so turning of crankshaft journals or line honing the carrier are not an option. We recommend upgrading to our coated Porsche bearings and ARP crankshaft carrier bolts on all rebuilds and having the crankshaft magnafluxed to check for cracks and the crankshaft journals polished.
Although the aftermarket pistons and connecting rods we supply are balanced out of the box (in fact often better than the original factory parts) and the dual mass flywheel provides significant dampening that makes up for imbalances, we do recommend at bare minimum static balancing all components. However, dynamic balancing of the rotating assembly is money well spent for any engine and recommended if you plan on tracking your car.
Who can rebuild my Porsche cylinder heads?
LN Engineering’s Porsche cylinder head rebuilding and porting service is available only to customers with qualifying purchase of Nickies cylinders, Nickies block sleeving, or Nickies Lite cylinder reconditioning services. Our cylinder heads benefit from years of experience with thousands of Porsche heads rebuilt by our specialists to date. 100% of components are tested, reconditioned, or replaced and feature multi-angle Serdi valve job, Viton valve stem seals, and critical surfaces are diamond milled, exceeding original manufacturer specifications. All components are inspected and replaced if worn. Additionally Porsche Boxster, Cayman, and 911 M96/M97 cylinder heads are always pressure tested and crack checked. All cylinder heads are vacuum tested after final assembly as part of our standard quality control checks so all you need to do is bolt them onto your engine.
Although cylinder head porting is available, in our experience most customers don’t need to as the Porsche did a great job on these heads and they already flow too much for the stock displacement. By bumping up displacement, you’re actually optimizing the engine and you’ll feel and see the performance increase through a wider, flatter torque curve that provides higher average HP and torque across the whole powerband. If you are looking to get every last bit of power out of your rebuild, porting will help the top end, especially when paired with an IPD competition plenum and GT3 throttle body.
Unlike aircooled Porsche cylinder heads where they can benefit from larger intake or exhaust valves, performance valve springs, and lightweight retainers, M96 and M97 cylinders heads come from the factory configured very well, even for track use. In the event that new valves, springs, or retainers are needed, we use Genuine Porsche or OEM replacements. Likewise, the factory camshaft profiles are excellent even with increased displacement and we rarely see any wear on camshaft lobes requiring repair or replacement. The X51 power package added high flow heads, intake plenum, oil system upgrades, and performance camshafts to the 3.6 and 3.8 engine, of which it is possible to purchase this kit or the cams from Porsche separately or you have your original 3.6 or 3.8 camshafts reground to an X51 profile by someone like Webcam Camshafts.
Who can rebuild my Porsche engine, what should I expect to pay, and how long does it take?
LN Engineering’s close partnership with Jake Raby’s Flat 6 Innovations delivers turnkey proven M96 and M97 performance engines for owners of Porsche Boxster, Cayman, and 911 models featuring all our improvements including Nickies sleeves, IMS Solution, and countless other upgrades co-developed by the LN/FSI team. Unfortunately, with so many engines needing to be rebuilt, there are simply too many engines for Flat 6 Innovations or our RND Engines builder to fill the needed demand.
We recommend taking a look at the IMS Solution Certified Installer list as most, if not all, of the shops listed have been extensively trained by Jake Raby including on how to properly rebuild the M96 engine. A proper rebuild for a Porsche engine typically starts at around $15k and closer to $20k if you are planning on doing additional upgrades for the track for the engine alone. What many do not factor into the cost is engine R&R (removal and reinstallation) as well as replacing worn ancillaries that are often overlooked by most shops when estimating these jobs. Please keep this in mind when budgeting for your engine build.
Typical turnaround time from start to finish is 3–4 months and that includes time for whomever you choose to rebuild your engine to disassemble it and send us the block and IMS for reconditioning. Typical turnaround is 6–8 weeks for us to process your block and the majority of that is spent at the platers where the bores finished after we machine the blocks to accept our Nickies billet aluminum sleeves.
What do I do if my 2009 and later Boxster, Cayman, or 911 with the 9A1 or MA1 engine suffers bore scoring?
Unfortunately, any engine with a hypereutectic engine block can suffer from cylinder bore scoring, not just the M96/M97 engine used in Porsche Boxster, Cayman, and 911 models. LN Engineering also offers services to recondition the MA1’s Alusil engine block as well we any other model with an Alusil block including the Porsche 944, 928, Cayenne, Panamera, and Macan. Unlike the M96 engine, we can do our Nickies Lite process where we can do a slight overbore then plate the cylinder bores, which allows us to correct the cylinder bore scoring without having to sleeve the engine block.
Do you have any additional information on how to properly rebuild my Porsche engine?
LN Engineering provides educational resources, training, and guidelines at no charge to its aircooled and watercooled Porsche customers. Be sure to check out our education library with dozens of free downloads and sign up for our valuable newsletters that offer original technical content that we think every Porsche owner should know. We’ve highlighted information specific to rebuilding and maintaining your Porsche Boxster, Cayman, and 911 with the M96 or M97 engine to supplement The Knowledge Gruppe’s Focus on M9X Engine Assembly DVD, Workbook, and Torque Spec books.
We also recommend checking out the LN Engineering YouTube Channel with great videos featuring industry experts Tony Callas from Callas Rennsport, Lake Speed Jr. from Total Seal (and previously Driven Racing Oils), and many others.
Originally written by Charles Navarro for LN Engineering.