RE:Re: <All> V6 vs. L6

[Neil Maller <neilmaller@xxxxxxxxxxxxxxxx>]

On 8/26/98 4:03 AM Rodney Moore m6bigdog@domain.elided wrote:

>Some of the flat engine configurations such as the 4 cylinder may be 
>balanced with respect to free inertia forces but are not inherently balance 
>with respect to free inertia moments, of which the flat 6, L6 and V12 are.
>In reference to your post: "Wrong" and "Any" may be a poor choice of words. 

Maybe, but I don't think so. The original claim attributed to R&T was:

>The only two configurations that are inherently balanced (vertical
>& rotational 1st and 2nd order forces) are an L6 and a V12.

I replied:
>Hmmm, if that's what they said, then they're wrong. In addition to the 
>L6, a flat engine of any even number of cylinders has inherently balanced 
>1st and 2nd order forces.

I might have added that for this to be true the opposing cylinders of a 
flat engine need to be on their own crank throws, but that's typically 
(always?) the case. Of course like some other engine layouts, flat 
engines also develop a rocking couple, but that's not the 1st or 2nd 
order force referred to.

All of which made me curious enough to go dig out the issue of R&T in 
question (Sept 98), which I hadn't yet read.

In fact R&T did not make the claim that the original post said they did.

My "if...then" response above and statements regarding flat engines are 
both correct, and so is Rodney's comment about rotational moments.

It's worth reading the article in question, which goes into more detail 
than appropriate here.

Neil
96 M3

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