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RE: Crank Balancing ( Math )

To: "Dale Krumheuer" <dmirror3@yahoo.com>,
Subject: RE: Crank Balancing ( Math )
From: "Albaugh, Neil" <albaugh_neil@ti.com>
Date: Tue, 12 Oct 2004 16:48:53 -0500
Dale;



Think of a V-12 as being two inline- 6s arranged in a "vee". The I-6 is
inherently a balanced layout so a V-12 will be as well. Ditto for a
flat-12 like a Ferrari 512.



When you take a balanced inline (straight) 6- cylinder engine and rotate
every other cylinder 60 or 90 degrees, the planes of the cylinder banks
are now out of balance.



No, a V-twin can't be completely balanced. Theoretically, if you had a
horizontally- opposed two- cylinder engine with no offset between
cylinders (forked rods) and fired both cylinders at the same time, it
would be in "balance" but the torque ripple would be equivalent to a
single-cylinder.



Here's some interesting reference material on balancing; it is written
primarily with aircraft (Lycoming?) in mind but I think you will find it
useful:



http://www.prime-mover.org/Engines/GArticles/BALANCE.Lyc



Regards, Neil    Tucson, AZ



-----Original Message-----
From: Dale Krumheuer [mailto:dmirror3@yahoo.com]
Sent: Tuesday, October 12, 2004 1:50 PM
To: Albaugh, Neil; Rick Yacoucci; land-speed@Autox.Team.Net
Subject: RE: Crank Balancing ( Math )



Ok Neil, now that you gave me enough information to get me thinking, why
is it that you can completely balance a V12 but not a V6 ? Now, to
reduce the question, can a V-twin be completely balanced ?

Thanks Neil,

Dale Krumheuer

Cleveland Ohio, where its gettin' cool

"Albaugh, Neil" <albaugh_neil@ti.com> wrote:

        Rick;



        It isn't possible to balance a 4-cylinder engine completely, no
matter
        what you do. All you can do is minimize the vibration.



        On the other hand, an in-line 6 cylinder engine or a V-12 can be
        balanced but a V-6 or V-8 can't be completely balanced. There
are
        "rocking couples" that cause vibration in engines that do not
have
        symmetry.



        Now--- someone explain to me the rationale behind a 10- cylinder
engine.
        ??????



        Regards, Neil Tucson, AZ






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