14:1 compressiion ratio is amazing! The article doesn't say but I bet the engine requires the highest octane pump gas. That is one reason I won't buy a gas volkswagen due to the premium gas requirement.
Seems like these great engines are released in Japan and Europe but never make it to the USA. Conspiracy theories this is your cue to comment....
Variable valve timing allows the effective compression (in cylinder actual) to be controlled with valve duration of both intake and exhaust separately. Variable lift would also allow for the same lower compression.
Direct injection also cools the piston head and cylinder head temperatures.
Higher rates of EGR are another way to control peak combustion temperature.
Fuel injected at TDC and even after TDC in multiple stages are another way to eliminate preignition, since preignition requires the air and fuel to be ignited before the piston reaches TDC. The peak combustion pressure can even be delayed past TDC when a combination of these strategies are employed.
Next they should increase the compression to 25:1
Then it could handle lower grade fuel.
Oh and at that ratio, the spark plugs wouldnt be needed due to the high compression !
Now that would be efficient and powerful.
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I can't understand why my MPG's are so low..........
According to my rough calcs, a 70 mpg rating in Japan is ~45 mpg EPA here. Pretty good, but I'll believe it more when I see it actually in a production car. You need more than engine tweaks to get there. Still, its great to see new technology like this.
Interestingly, Mitsubishi's latest diesel engine has a 14.9:1 compression ratio. At this rate, gas and diesel engines will soon be running very similar compression ratios.
