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Cars & Coffee Killer
Join Date: Sep 2004
Location: State of Failure
Posts: 32,246
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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?
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Some Porsches long ago...then a wankle... 5 liters of VVT fury now -Chris "There is freedom in risk, just as there is oppression in security." |
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11-20-2006, 06:48 AM
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Registered
Join Date: Mar 2003
Posts: 10,322
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356/912 crankshaft - Boxer 4 cylinder - http://www.aapistons.com/NewsInfo.asp?id=99
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“IN MY EXPERIENCE, SUSAN, WITHIN THEIR HEADS TOO MANY HUMANS SPEND A LOT OF TIME IN THE MIDDLE OF WARS THAT HAPPENED CENTURIES AGO.” |
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11-20-2006, 07:28 AM
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Un Chien Andalusia
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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...    Flaming complicated, but you get the idea. Hope it helps!
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2002 996 Carrera - Seal Grey (Daily Driver / Track Car) 1964 Morris Mini - Former Finnish Rally Car 1987 911 Carrera Coupe - Carmine Red - SOLD :-( 1998 986 Boxster - Black - SOLD 1984 944 - Red - SOLD |
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11-20-2006, 07:44 AM
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Registered
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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.
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Tim 1973 911T 2005 VW GTI "Dave, hit the brakes, but don't look like your htting the brakes...what? I DON'T KNOW, BRAKE CASUAL!!!" dtw's thoughts after nearly rear ending a SHP officer |
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11-20-2006, 08:04 AM
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Bill is Dead.
Join Date: Jul 2005
Location: Alaska.
Posts: 9,633
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Nice text reference.
Do you have a machine shop?
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-.-. .- ... .... ..-. .-.. -.-- . .-. The souls of the righteous are in the hand of God, and no torment will ever touch them. |
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11-20-2006, 08:24 AM
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Un Chien Andalusia
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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.
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2002 996 Carrera - Seal Grey (Daily Driver / Track Car) 1964 Morris Mini - Former Finnish Rally Car 1987 911 Carrera Coupe - Carmine Red - SOLD :-( 1998 986 Boxster - Black - SOLD 1984 944 - Red - SOLD |
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11-20-2006, 08:34 AM
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Gon fix it with me hammer
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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...
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Stijn Vandamme EX911STARGA73EX92477EX94484EX944S8890MPHPINBALLMACHINEAKAEX987C2007 BIMDIESELBMW116D2019 |
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11-20-2006, 08:41 AM
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1973 Porsche 911 2.4 MFI
BimForce the Third, Esquire
