Re: AUDI & Mercedes

[rsco@lubrizol.com (Robert S. Cohen)]

>        While Audi developing 5 valve/cylinder ,the Mercedes's new line
>engines are 3 valve/cylinder ,including the new v-6 v-8 in the future
>        why...?? whose idea is better ?

The idea behind adding more valves to cylinder heads is to allow the engine
to breath in and out more efficiently.

That being said, there are alot of real-world engineering problems to be
overcome in adding alot of valves. An example follows...

Yamaha motorcycle engines, for example, have 5 valves/cylinder, and have
had for some time (in their homologated 4 cylinder engines). The design (to
my very limited knowledge) requires a goodly amount of spark advance,
exposing the engine to the heat of combustion for a longer period of time
than less (no pun intended) advanced designs. This in turn requires more
radiator area to pull the heat out. One of their factory
(vance&hines/yamaha) racers was disqualified earlier this year for running
a larger-than-stock radiator in his bike (FWIW, I believe he was winning
regularly :-)). The engines are also slightly more complex (costly) than
their 4 valve counterparts by virtue of the additional valve/valve train
parts.


What was the question again?

Rob

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Robert S. Cohen         rsco@lubrizol.com       Lubrizol Corp.,
NewMedia Inc.           ^^^ preferred ^^^       29400 Lakeland Blvd  MS 228,
Cleveland, OH                 -or-              Wickliffe OH, 44092
                        rsc2@po.cwru.edu        voice 216.943.1200 x 2012
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