The easiest way to see it is to map the extremes with a piece of paper.
Using a the same stroke, map the position of the piston for the minimum
length rod to clear the crankshaft and one that is twice as long. You'll see
that the piston position, and therefore the piston speed is very different
between the two for each degree of rotation. The piston has to wind up
stopped at both top and bottom of the stoke. As it approaches TDC on the
power stoke, the high pressure gasses have longer to press against the
piston with a long rod engine than with a short one because the piston
position doesn't change much for a relatively large number of degrees of
rotation. There are also potential gas flow advantages.
-----Original Message-----
From: owner-fot@autox.team.net [mailto:owner-fot@autox.team.net] On Behalf
Of Richard Taylor
Sent: Monday, June 13, 2005 3:45 AM
To: 'barry rosenberg'; triumph_marx@freenet.de; 'fot'
Subject: RE: 225hp
Okay. Help a neophyte. The way I see it, whatever goes on in the combustion
chamber is completely ignorant of the length of the connecting rod, whether
the rod is 4" long or ten feet long (assuming the same crankshaft throw.)
The only difference I can see is that the longer the connecting rod the less
the angle of "push" it has in transferring the vertical thrust of the piston
to the rotational movement of the crankshaft. Where have I gone astray?
Richard
-----Original Message-----
From: owner-fot@autox.team.net [mailto:owner-fot@autox.team.net] On Behalf
Of barry rosenberg
Sent: Monday, June 13, 2005 6:17 PM
To: triumph_marx@freenet.de; fot
Subject: RE: 225hp
It is my understanding that going over 1.8 to 1 ratio would increase
the rpm that maximum torque comes in and going below that reduces the rpm
that torque comes in. This was from Hot Rod web site. Also look at April
2005 Circle Track, two 2.5L Ford engine builders Racer Walsh and Esslinger
both have articles discussing the increase in torque from the longer rod
theory. Racer Walsh claims to have increases of 9-13 hp and 18-21 lb-ft of
torque. I read all this after ordering my rods and pistons but it gave me
comfort knowing I wasn't wasting time and money, I hope. Barry
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