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Old 12-03-2012, 11:24 PM   #223 (permalink)
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Join Date: Feb 2012
Location: Northeast USA
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Hi MetroMPG, yes I did the internet image search without much success. I was surprised how difficult it was to find a small turbo engine BSFC chart. I did see the Acura 2.3L turbo BSFC, but it did not apply. I really wanted a smaller displacement, economy car turbo BSFC chart. The Acura is a "luxury-performance" engine, less emphasis on economy and more on performance.

The Acura engine seems strange to me: The torque curve is very peaky(big turbo requiring more exhaust flow to get full boost?), mine is much flatter(small turbo for minimum lag and good low-end). The peak torque occurs at 4500 RPM out of a 6500 RPM redline, that's really high for a turbo engine! The efficiency island also seems too high up the load axis. The turbo should negate the pumping losses at lower loads, allowing the island to drop 20-30%(my guess). So unfortunately I didn't think this one applied.

I'm only talking about very light turbo boost -2 to +2psi, just enough to overcome the pumping loss. This also allows me to short-shift, I rarely go above 2000 RPM. One person on CleanMPG stated that you need to stay out of the boost for efficinecy, that's where I disagree, 'mild' boost recovers some of the lost energy in the exhaust.

I did also see the Volt NA engine, however in this case it doesn't apply because it is tuned to run over a very narrow operating envelope. As you know, it is not coupled to the drive wheels, so the engine control forces it to operate only along the red line on the chart.

Thanks for the effort, but it looks like there is no small turbo engine BSFC charts that are easily available.


P.S. I am in awe of you real modder guys! Awesome projects! I'm just a hack, got the grille blocker, thinking about smoothing out the nose & extending the rear spoiler over the hatch to make a longer Kammback! It takes a lot of work to make real gains...
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