The Step By Step Assembly of a 2.9 Big Bore M96 engine
By Jake Raby
In the following pictures you'll see what is required to assemble a Porsche M96 engine at the Performance Level. This engine started life as a 2.5 Liter M96 from a 1999 Porsche Boxster that had suffered several different modes of failure to include slipped sleeves, failing IMS, and ultimately the "D Chunk" failure that ended in a catastrophic loss of life for the engine.
This engine had previously been "Remanufactured" by Porsche as part of their replacement engine program and the case had been welded in several areas, MMC cylinder sleeves installed, and other standard procedures performed by the Porsche Remanufacturing program. The outside of the case was marked with the tell-tale blue paint so many of these problematic reman engines have been identified by.
We chose this engine case for our latest test engine, because it was by far the WORST crankcase that we had ever experienced, and if any engine was doomed to fail while creating higher performance, this one was it! In the pictures you'll notice that the case has several stains and may appear dirty, but these are made much worse by the camera and lighting of the assembly area.
Note: We'll be leaving the big, fancy words for another day and I'll do my best to help the "normal people" reading this article understand in laymans terms what the images depict.
We'll begin with the "Heart" of the engine. The Crankshaft
This crankshaft started life as a stock stroke unit from a 2.5 liter Boxster, it was subject to our stroking process that took it's stroke to 78.4mm. The Crankshaft was also subject to Ion Nitriding process to enhance it's wear resistance and to acheive the best longevity along with our PC3 (friction reduction coating) coated main and rod bearings.
The crankshaft along with the remainder of the dynamic assembly was then balanced and indexed using our own in-house digital dynamic balancing equipment.
Here the reworked and updated 78.4mm Crankshaft is pictured after being sterilized, ready for assembly.
Here the Crankshaft "Carrier" or "Cradle" is after being measured for wear and straghtness, prior to the main bearing inserts being introduced. This is a two part assembly that assembles much like the crankcase halves would in an aircooled Porsche engine of yesterday. This carrier houses the main bearings (14 inserts) as well as the shims used to set crankshaft end play.
Here the R&R Pro Billet Chromoly Connecting Rods supplied by LN Engineering. These units are MUCH stronger than stock as they feature a stronger H beam design as well as ARP 2000 rod bolts. The M96 engine has become notorious for rod bolt failures with the OE rod bolts, these "Overkill Engineered" rods and their rod bolts will never have that problem! These best part is a full set of these rods costs less than Porsche replacements and they can be rebuilt due to their design. The stock rods are disposable as they utilize "cracked cap technology" like most other modern engines. The markings on the rods depict the actual bore dimension of the rod with the bearing installed and the rod cap torqued as part of our blueprinting procedures.
This is a reality when an engine is assembled by a detail oriented Human, not a Robot.
Here the Flat 6 Innovations custom main bearings are shown with the PC3 Friction Reduction Coating applied, ready for final cleaning and assembly into the crankshaft carrier assembly.
Main Bearings installed into the carrier, ready to be lubricated for crankshaft introduction. (Running clearances were previously measured, verified, and recorded)
Insertion of a main bearing insert into the crankshaft carrier.
Both portions of the crankshaft carrier with inserts installed.
After some heavy lubrication with our engine oil used for assembly, the crankshaft is introduced into the crankshaft carrier.
The crankshaft must be introduced into the portion of the carrier that houses the relief for the crankshaft end play shims.
Only one half of the carrier assembly has these reliefs on the center main saddle.
Another shot of the relieved center saddle...