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Registered User
Join Date: Jul 2001
Location: Portland Oregon
Posts: 6,992
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Hi:
These engines have 4-valve heads that can flow a LOT more than the average air-cooled 2-valve heads can and through a much wider range of valve lifts.
Add high-compression, VVT, and variable geometry intake systems and you can achieve 100 HP/litre and still remain drivable and smog legal.
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