Quote:
Originally Posted by The Wind Breezes
You are right, I didn't mention RPM. And that R1 is old hat. New superbikes make almost 200bhp. Anyway, for shits and giggles let's see what would happen if you gave the N52 superbike compression and all the trick bits to make it flow a lot better, without raising the RPM. We'll say flow increases 5% in efficiency in the upper RPM which is reasonable. Stock compression is 10.7:1. A S1000RR has 14:1 compression and runs on pump gas. Then let's say we use E85 vs pump gas. E85 needs a lot less air to burn so you can stuff more in the motor. Even though the energy content is less you still end up with about 10% more power potential other things equal.
So you've got:
+5% efficiency
14:1 vs 10.7:1
+10% E85 boost
We'll say a N52 makes 270bhp stock, being generous.
270 * 14/10.7 = 353
+ 15% = 405 bhp
So even if you don't run ethanol, and just use whatever octane gasoline is necessary to support 14:1 compression, you can make an absolute shitload of power.
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An N52 in 128i trim is ~ 230 base to start with, and with that swept volume running 14:1 on 85 octane is unlikely to work out too well.