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marshknute
11/13/18 10:03am

As a Corvette owner, I should know this: Why are small-block Chevy V8’s so much smaller/lighter than a DOHC, despite their huge displacement? For example, my “huge” 6.2L LS3 is apparently smaller and lighter than the “tiny” 4.0L S65 from the E90 M3.

And if the small block is so powerful, reliable, light, tiny, and fuel efficient, why did we ever bother inventing the DOHC in the first place?

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    DeWayneV8
    11/13/18 10:12am

    They’re light because the heads are small and they only have one camshaft, as opposed to four that a DOHC V8 would have.

    DOHC was developed because it provides much more valvetrain stability (read: more revs and reliability), and far superior breathing. In modern terms it also allows much more fine control over combustion because you can change the intake and exhaust valve timing relative to each other. It’s like having infinite camshaft selection all the time.

    The pushrod V8 will die. It cannot provide the combustion efficiency of a properly engineered DOHC configuration and so it will be regulated out.

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