If you're going to look at modifications to the HPFP, here is what you need to achieve. "Tested Engine" is our LNF, "Optimized Engine" is an optimal design (for fuel efficiency) for a Flex Fuel version of the LNF:
Table 3: Specifications of fuel system components
Components Tested Engine Optimized Engine
Fuel Pump 3-lob cam driven, 0.9cc/rev 4-lob cam driven, 1.1cc/rev
Injector 22.5cc/s 22.5cc/s, optimized spray targeting
Fuel Rail 135cc, 150bar 66cc, 200bar
Pressure Sensor 200bar 260bar
All of this comes from here (in case none of you have read this before):
http://www-personal.umich.edu/~annastef/papers_FFV/Optimally_Controlled_FFV-final.pdfI also have a copy of the PowerPoint presentation that goes with this from the Federal Government Review (this research was federally funded).
If someone from BOSCH is coming (from the Cobalt thread), then I hope it's Hakan Yilmaz. He's the guy in the know currently at BOSCH when it comes to the LNF and Flex Fuel.
It's been my understanding since 2010 that Walbro made the pump used in the testing cited in this report. I don't know who made the modified pistons though. I've been told there are two pumps, one in the HHR SS used for testing, the other on a bench conducting life testing... life testing was due to complete March 2012... hmm... that's now.