Engine Design Philosophy

[Bernie Benz]

Please explain your meanings of simplex vs. duplex in this respect.

Bernie
On Nov 14, 2011, at 8:21 AM, Matt Suffern wrote:

> Someone explain this to me.  Looking through the parts catalog I study
> the valvetrain diagram for the 3B.  I notice Audi has retained a
> timing belt design with a simplex chain to link the exhaust camshaft
> with the intake.  My BMW 525's M50, by contrast, has a duplex timing
> CHAIN with, again, a simplex chain linking camshafts.
>
> Both engines can last upwards of 300K miles.  So why the overkill on
> BMW's part?  Four more valves to operate (1 more cylinder)?  Or did
> they just assume people aren't going to do regular maintenance like
> timing belt changes?  It just seems like an awful lot of added
> complexity and valvetrain inertia to avoid a procedure most people
> assume is going to have to be done anyway.
>
> Curious.
>
>
> Matt
> Winston-Salem, NC
> www.spannerhead.com
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