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      12-13-2013, 11:44 AM   #54
solstice
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Drives: 2015 M3 6MT
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Quote:
Originally Posted by Boss330 View Post
The original engine (assuming you mean N55) made 300hp with 0,5bar boost. Hardly any boost at all. Under ideal conditions a boost of 0,5bar increases power by 50%. In the real world a bit less. So the base N55 engine makes somewhere around 220hp unboosted. A VERY mildly tuned 3l engine from BMW the N55.

A Nissan GT-R can be tuned to 650hp on stock turbos:

http://aamcompetition.com/i-11658595...r-package.html

Why is the S55 not capable of at least half of the gain (100hp) the GT-R has on stock turbos?
You also need to consider the compression ratio. The GT-R run 9:1 and peak boost around 13psi stock. The M4 runs 10.2:1 and 18 psi. Fuel self detonation is a limitation if you want to run on standard 93 octane. The M4 has a lot less room to increase combustion pressure than the GT-R. My guess is that there is little room left on the M4, maybe just enough for a symbolic boost for the comp. pack.
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