Engine Balance
 

Educate me.

Inline four cylinder engines generally have balance shafts.

V8's have harmonic balancers on the crankshaft.

What do six cylinder engines have? What about V12s? Boxer 4's?

It seems to me that inline 4 and V8s should be a balance desinge, while V6's and Boxer 6's should produce tons of vibration. What am I missing?

356/912 crankshaft - Boxer 4 cylinder - http://www.aapistons.com/NewsInfo.asp?id=99

The short answer is that there isn't a short answer. Engine vibration is determined by the number of cylinders, the bank angle (angle between the cylinders on a V), and crank offset angles, and ignition intervals.

I'll see what I can find that explains it...

http://forums.pelicanparts.com/uploa...1164040795.jpg

http://forums.pelicanparts.com/uploa...1164040823.jpg

http://forums.pelicanparts.com/uploa...1164040863.jpg

Flaming complicated, but you get the idea. Hope it helps!

interesting to note that flat 4's, flat 6's, inline 6's and v-12's have no free forces or moments, which I believe means they're inherently balanced.

Nice text reference.
Do you have a machine shop?

cashflyer - if you mean me, no, I don't have a machine shop as in own one, but I have spent a lot of time working in, around, or with them.
;)

what Tim says ,


inline 4 is really a pisspoor design in terms of vibrations, V6 -8 - 10 aren't that much better either...

VW's VR6 on the other hand is a close call, as it is technically closer to an inline 6 then it is to a true V6...

once saw a swedish dude take apart a BMW V12 from a 760I ... after a gazillion miles, the main bearings hardly had visible wear on them...