Quote:
Originally Posted by Blue Angel
Found this old thread and wanted to add some info.
The newer systems like the one in the Cruze use an intelligent driver to manipulate the fuel pump RPM to vary fuel pressure and flow as required. As far as I know, no pressure regulator is used so every bit of gas pumped by the fuel pump is required by the engine. It wouldn't surprise me if lots of vehicles are using this system by now.
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I don't know how prevalent they are yet, but ther are coming soon.
An Electronics supplier showed me today, as an example about the power of Matlab software, a PWM ECM controlled variable speed fuel pump with feedback loop to maintain the exact pressure at all times.
On a sample Mini Cooper run through Matlab Simulink, baseline fuel pump was 95 watts constant. Variable speed was averaging in the 55 watt range. And a brushless variable speed was in the 30 watt range.
To convert to theoretical FE changes, more Matlab analysis indicated a 0.5% to 1.5% FE increase due to reduction in alternator load. They considered this low hanging fruit, even though it was small, but measurable, FE improvement.