Frequent readers of ABG know we keep track of the way Saab has been working on a small, powerful E85/E100 optimized engine that can also use gasoline though that will cause a power reduction. Car and Driver magazine's Csaba Csere reports on another variation of this basic theme: Downsize the engine but increase the compression ratio; use direct fuel injection and a turbo or supercharger, use gasoline for most of your driving because most driving is low load driving. However, when it is time to put the pedal to the metal, the fuel will switch from E0 (gasoline) or E10 (gasoline with alcohol oxygenate) to E85. The ethanol suppresses detonation because of its high octane number (about 104 or so) and the direct injection results in a lot of evaporation which cools the charge and prevents knock.
One the negative side, there needs to be two tanks for fuel and, I surmise, two fuel systems so there is no lag when the fuel is switched. Run out of E85 and your run out of high performance, just like on the single tank Saab system.
On the positive side, most of the components would not be expensive and are of known technology. There would be savings in weight and in efficiency both on gasoline and on E85. The developer – a company called EBS (Ethanol Boosting System) - says more gasoline would be displaced in this way than in an E85 vehicle running E85. I will wait to see the numbers before I sign on to that one. Still, this will hopefully spread use of E85 beyond the 1,000 or so stations that carry it in the US. By using improved performance to attract buyers, this is a smart way to reduce dependence on petroleum without sacrificing the performance we like to know our vehicles are capable of. No emissions penalty either.
[Source: Car and Driver]
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