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Old 12-28-2013, 08:31 AM   #18
RickB
Scraping Paint
 
City: Fort Lauderdale
Vessel Model: CHB 48 Zodiac YL 4.2
Join Date: Oct 2007
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Quote:
Originally Posted by FF View Post
I'd be quite curious as to what sort of factory upgrades were done to the bottom end, because a doubling in power implies a doubling in cylinder pressure.
That ignores the fact that the high power engine develops its rated output at a higher rpm and ignores the fact that the engine uses a bypass blower that at high power is essentially non-existent compared to the large parasitic load imposed by the standard blower.

Also, don't for one moment think that BMEP is actual cylinder pressure.

Consider that the larger number of power strokes resulting from the increased rpm above the NA version, along with the availability of the power that is consumed by the blower on the NA versions, along with higher volumetric efficiency and better scavenging contribute greatly to power output.
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