Quote:
Originally Posted by twinturbo135i
the N54 has something like 10:1 compression ratio on top of being assisted by the twin turbos. I still have a hard time understanding how can an engine that comes stock with such high compression can withstand having even more stress when the boost kicks in.
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The reason why the N54 doesn't go boom with a high compression ratio is because it utilizes direct injection. When fuel is injected directly into the cylinder, it naturally cools the cylinders allowing for more aggressive timing and thus, greater output. Its really the same principle behind any type of Methanol/Water injection. Cooling the cylinders results in greater thermal efficiency and allows the addition of more boost.
Oh, and the compression ratio of a motor doesn't change. Compression ratio is the difference in cylinder volume between when a piston is at the bottom of its stroke to when it is at its highest.