Quote:
Originally Posted by sterile stork
This is just a fantastic post! Thank you so much for gathering all the data and presenting it in such a clean manner--it really highlights the wonders that are the S65 although we may all be biased toward it  |
^ +1 OP: Thank you for posting this! I enjoyed listening to all the different iterations as well.
Quote:
Originally Posted by aus
Anyone know if they're running a flat plane crank?
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^Yes, the P65 uses a BMW Motorsport-derived flat plane crankshaft with revised firing order of 1-8-3-6-4-5-2-7.
The S65 has a firing order of 1-5-4-8-7-2-6-3, and uses a cross plane crankshaft.
The P65 bore and stroke are the same as the S65 production engine (92.0 x 75.2) for a total displacement of 3999.2 cc. The engine also uses the same double vanos and throttle by wire systems as the S65.
The exhaust system is provided by BMW Motorsport, and uses a small muffler on each side to meet the old ALMS sound pressure rules (no more than 112 dbA measured 15 meters from the edge of the track). The headers and exhaust system are customized for the GT2 car. (proprietary info, no details)
The P65 engine sounds unique due the combination of a flat plane crank, revised firing order of the cylinders, and the exhaust modifications.