Saab's Biopower: Getting more fuel efficiency, performance from e85

EV World: The World of Electric, Plug-in Hybrid, Fuel Cell and Alternative Fuel Vehicles:
by Chris Ellis -- 10/9/2005
"Equally interesting is Saab's BioPower engine. While the application of flexible fuels has been pretty casual in most US designs, Saab have done a professional job on their latest engine, now that Sweden is committed to biofuels. As any petrol-head knows, high compression is good in a gasoline engine, and a key limitation is the octane rating of the fuel, typically 95 or so globally. But E85 is 104 octane, which potentially means more power and better efficiency, and a reduction in the compression ratio advantage enjoyed by diesel. As a general statement, US E85 engines are naturally aspirated and must run with gasoline compression ratios. That means they take no advantage of the superior efficiency that E85 affords. Bearing in mind that GM owns Saab, let's imagine what a US Saab might be able to do by next year, using technology that is already shipping all over Sweden. "