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      07-25-2018, 06:18 PM   #16
rowsdower
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Drives: 2011 128i 6MT Sport
Join Date: Jan 2017
Location: Texas

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Quote:
Originally Posted by The Wind Breezes View Post
The engine's a tank because it's ridiculously detuned from what a NA 4 stroke of that displacement and cylinder surface area to volume ratio can produce. A CRF250R makes 40 hp out of .25l on pump gas. It's true, the surface area to volume on that motor is better but you can extrapolate. The biggest problem is lack of dry sump, but that may not show up for a long time without slicks.
This is a somewhat absurd comparison. The engines are drastically different and the peak horsepower is largely due to engine speed. All sport-oriented motorcycles spin at much higher RPM than our engines and produce far higher HP/liter figures as a result. I couldn't find a dyno graph for the bike you cited, but an R1 makes 167hp out of a 1 liter motor... at 12,300RPM!

I'm not claiming our engines are peak performers at about 77hp/liter, but it would make more sense to compare against other 6-cylinder engines in the 3 liter range that have similar redlines. A 370 is in the ballpark at 89hp/liter for example. Clearly higher than our engines but not 160hp/liter. Even an S2000 is only at 120hp/liter and that's considered an extremely high output engine, but again that engine revs to 9k which explains a lot of that.
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