Quote:
Originally Posted by adam728
In some ways a simple 2V engine can do very well for efficiency due to swirl characteristics that can be designed in. 4V engines generally need to use more tumble, getting ports setup for swirl is hard to package, and doing different variable lift or opening just one to promote swirl ads a lot of cost and complexity.
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David Vizard patented (US 2002/0185105) a "PolyQuad" 4v setup where different sized exhaust and intake valves and some shaping in the combustion chamber are used to promote swirl. He's also mentioned experiments grinding one of the pair of lobes for exhaust or intake so that duration is about 5 degrees less on one, and he saw different results depending on whether the pair of valves were opening together or closing together.
Elio's custom engine sounds like a good way to push off production whilst burning through investors money.
cheers,
Michael