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      07-11-2013, 11:45 PM   #272
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Drives: E92 M3
Join Date: Sep 2006
Location: San Diego, CA USA

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Originally Posted by NISFAN View Post
Swamp, this engine looks like a generator pack diesel. Note the increase in torque, but constant revs (almost). This can only be due to a load that increases with power output, like a generator set.

In any case the torque delay on the un assisted turbo doesn't make any sense. Lag that lasts for 4.5 seconds plus? No chance. More likely due to an uncontrolled wastegate, which starts boost leak very early, or other factors.
These graphs are actually for an off highway 4.4l diesel engines. I do not know what loads were used in the test but indeed they are not constant. Anyway, the point was not at all to provide an actual time duration typical for turbo lag in a modern road going automobile (I'm well aware that 3.5 seconds of lag is not typical in such cars...). The point was to show cleanly and conceptually the differences between different approaches, including an full electric turbo design, and what their transient torque curves will look like. Compress the x axis quite a bit (or equivalently change the scaling) and the comparison would be more technically correct.

I sure hope we can get some sort of similar real world transient torque test from BMW M upon release of the first big "dump" of tech info on the new engine. I'm sure they have some graphs about turbo lag (or lack thereof) but they don't always have the most clear technical marketing. There will be plenty of overuse of the work "dynamic" for sure...
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