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William · 03-13-2002, 08:47 PM

this "mr.X" sounds like a really cool guy...

"*the connection rod and crank are solid objects, with a fixed connection, they do not change lenght, thats why going up and going down are the same lenght, so if it went 2mm down extra it will go 2mm up extra!"

This is where you are wrong.  I'm going to use a a lot of abstarct numbers here that would never be applied in real life to illustrate a point.  say our stroke is 5 and our rod length is 5.  We want to stroke this engine.  We would make the stroke 6 and the rod length 4, assuming we're using the same pistons (for arguments sake).  this means that at TDC they both still add up to 10, so valve clearances aren't an issue.  However, at BDC, our longer stroke is bringing our shorter rod further down the bore.  

"stroking adds a great deal of stress to the block, this is from the rod ratio and the compression ratio increase"

Stroking does nothing to the compression ratio, as I illusrated in the first paragraph, and it DECREASES the rod ratio.  In my example, the rod ratio went from 5/5, or 1/1, or 1, to 4/6, or 2/3.  This "stresses" the engine because the rod angle has just become more severe.  

Now I didn't read your entire post, as these were the main points I was interested in arguing.

03-13-2002, 08:47 PM	#2
William Leaky Injector Join Date: Feb 2002 Posts: 90 Trader Rating: (0)	this "mr.X" sounds like a really cool guy... "*the connection rod and crank are solid objects, with a fixed connection, they do not change lenght, thats why going up and going down are the same lenght, so if it went 2mm down extra it will go 2mm up extra!" This is where you are wrong.  I'm going to use a a lot of abstarct numbers here that would never be applied in real life to illustrate a point.  say our stroke is 5 and our rod length is 5.  We want to stroke this engine.  We would make the stroke 6 and the rod length 4, assuming we're using the same pistons (for arguments sake).  this means that at TDC they both still add up to 10, so valve clearances aren't an issue.  However, at BDC, our longer stroke is bringing our shorter rod further down the bore.   "stroking adds a great deal of stress to the block, this is from the rod ratio and the compression ratio increase" Stroking does nothing to the compression ratio, as I illusrated in the first paragraph, and it DECREASES the rod ratio.  In my example, the rod ratio went from 5/5, or 1/1, or 1, to 4/6, or 2/3.  This "stresses" the engine because the rod angle has just become more severe.   Now I didn't read your entire post, as these were the main points I was interested in arguing.