What is it about (all?) straight-sixes that renders them perfectly
balanced, as most authorities seem to say?

Does a V-12 have the same perfect-balance architecture, or does that
depend on the V-angle, and if so, why?

Lastly, about 40 years ago a standard first-year college text was
Rouse's Automotive Eng --- does it still exist or is there a better
alternative for someone who never passed a sci/eng course in his life?

brafield (AT) hotmail (DOT) com wrote:
http://auto.howstuffworks.com/question366.htm
http://www.answers.com/topic/flat-engine

--
forty

“To embrace an extreme, one must first let go of reason.”

On Apr 26, 10:36 am, forty <cfort... (AT) SPAMgmail (DOT) com> wrote:

On Apr 26, 10:36 am, forty <cfort... (AT) SPAMgmail (DOT) com> wrote:
--.+++

brafield (AT) hotmail (DOT) com wrote:
Put simply it's because everything balances out - if there is a mass
moving in one direction on a 6 cylinder engine, then somewhere there is
a mass moving in the opposite direction at the same speed. AIUI It isn't
quite true that they're perfectly balanced, because every time there is
a bang, you have an out of balance force that isn't compensated for by a
bang in the opposite direction. But mechanically, they are perfectly
balanced. (The above is a quick summary of
http://en.wikipedia.org/wiki/Engine_balance)

Yes

No.

The wikipedia page recommends the Bosch Automotive Handbook as a useful
reference, and it is good, although I find it a bit shallow. The SAE
publishes a book called The Handbook of Automotive Engineering, which I
own but haven't had time or chance to really read much of -
http://www.sae.org/technical/books/R-312 - it's more or less a bible of
vehicle engineering, and it seems well written and comprehensive. I
don't know if it's what you're looking for but the write-up says "If you
are an engineer or automotive specialist who seeks to expand his or her
knowledge, or a technically interested person, student, and
non-technical layman who wishes to learn more about the modern
automobile and its systems, this handbook is the reliable source for
day-to-day advice and information." It is USD140 so perhaps worth seeing
if a library near you has a copy...! I was lucky enough to be given mine.

--
Phil

http://www.flickr.com/photos/tmc1979/

On 26 Apr 2007 10:26:15 -0700, "brafield (AT) hotmail (DOT) com"
<brafield (AT) hotmail (DOT) com> wrote:

6 cyl engines are always working. There are virtually no dead zones in
the firing, hence vibrations are reduced.
That still doesn't mean that they don't need a harmonic balancer
though.

At a guess, a V shape will introduce some more vibration, since the
cylinders are not firing upwards, but i'm not sure if that even
flies..

--

Regards, Frank

On Thu, 26 Apr 2007 22:22:40 +0100, Phil Newnham <pnewnham (AT) yahoo (DOT) com>
wrote:

stationary, until the active piston is done with it's bang.. ;-p

said it was the most balanced engine configuration. To which the guy i
worked with at the time said "WTF?".
Audi dropped that claim shortly after the release, so i'm guessing a
few more people asked that very same question direectly to them.

--

Regards, Frank

"brafield (AT) hotmail (DOT) com" <brafield (AT) hotmail (DOT) com> wrote in
news:1177608375.662863.205930 (AT) c18g2000prb (DOT) googlegroups.com:

rotary engines? Surely they are better balanced than straight six?

On Thu, 26 Apr 2007 at 17:26 GMT, brafield wrote:
Here is nice link:
http://tinyurl.com/2259ke

While most think the best V-angle for a V12 is 60, Ferrari
prefer a 65.

--
(Mark Webber) talking about Turn 11 and 12 which all the drivers and
teams do now, which is such a shame. I think thats Abbey Chicane youve
got these great corners with lots of heritage, like Copse and Stowe
and Club but they just get turfed out of the window for numbers, and
its a pity.

a_Frank wrote:
Well, a piston can be said to be temporarily stationary at top dead
centre, but no, the point is that in other configurations there are
always out of balance loads at some point during the cycle, whereas in a
6 cylinder inline or flat engine, or a V6 with a 60 degree bank angle,
there aren't (apart from the actual bang, AIUI). But I'm not an engine
designer and I am aware that wikipedia isn't the best source. I'd look
in my vehicle engineering book but it's at uni and I'm not.

Wikipedia mentioned that several configurations that aren't perfectly
balanced have been labelled perfectly balanced by the selective
definition of what's included or not included.

--
Phil

http://www.flickr.com/photos/tmc1979/