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RE: FW: Crankshafts

To: "'Larry Young'" <cartravel@pobox.com>
Subject: RE: FW: Crankshafts
From: Bill Babcock <BillB@bnj.com>
Date: Fri, 28 May 2004 06:38:09 -0700
I'd like to see it.

-----Original Message-----
From: Larry Young [mailto:cartravel@pobox.com] 
Sent: Friday, May 28, 2004 6:37 AM
To: Bill Babcock
Cc: Fubog1@aol.com; tstrange@sbcglobal.net; sbarr@mccarty-law.com;
jerrybarr@charter.net; fot@autox.team.net
Subject: Re: FW: Crankshafts


The crankshaft position, speed and acceleration differ from a straight 
sin/cos function by an extra term involving the connecting rod length.  
This extra term accounts for the assymetry between the speed on the top 
half and bottom halves of the stroke.  An inline 4 cylinder engine is 
inherently unbalanced due to this assymetry.  A longer connecting rod 
makes the top and bottom halves more nearly symmetric, giving better 
balance.  Some modern inline 4 cylinder engines use an extra balance 
shaft to compensate. I've got the formula coded in a spreadsheet if 
anyone is interested.
Larry Young

Bill Babcock wrote:

>I seem to remember that speed is a sine curve
>and acceleration is a cosine, but I really don't remember this stuff, 
>but I'll pull out my ancient copy of Ricardo tonight and refresh my 
>memory.

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