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Originally Posted by Allch Chcar
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You didn't read much of the article that came out of did you?
The authors took a Ponticac Solstice engine, a 2.0 turbo direct injected engine, and heavily modified it into a single cylinder research engine. They took the turbo off and essentially blocked off three cylinders. They deleted the cams completely and ran with fully electronic valves.
They were investigating how much timing they can run with E85 on high compression pistons compared to running on 87 and 91 octane. Then they used the electronic valves to experiment with various unconventional valve timing strategies to reduce the effective compression ratio.
The whole point was to investigate the concept of a high compression E85 n/a engine that could be detuned for pump gas by using a Miller cycle. Look at the piston designs. They started with the 9.2:1 and made some prototype higher compression pistons. Notice that the higher compression ones have smaller and smaller piston bowls. That will cause all sorts of mixture formation issues on the D-4S system. Pistons on direct injection engines are a lot more complicated.