On 16 Oct 2006 15:49:43 -0700, "basskisser"
wrote:


CR wrote:
"basskisser" wrote in message
oups.com...

CR wrote:

Wrong. Low end torque is not enhanced by bore size as long as the overall
displacement of the engine remains the same.

Prove it.



"Engine torque output is essentially related to cubic inch displacement of
any engine. The RPM that maximum torque is produced at is related to the
length of the stroke of any engine. A 230 c.i.d. "under-square" engine will
make about the same torque as a 230 c.i.d. "over-square" engine but will do
so at lower RPM due to its longer stroke."

http://www.novak-adapt.com/knowledge...es_general.htm

What you fail to realize, is that you need to think of the connecting
rod as a lever.

Actually... a longer rod does not change the force on the crank at all
- the "lever" is the offset of the crank pin from the crank centerline
- i.e. half the stroke.

Basically, the rod isn't a "lever", it's a vector. The "leverage"
doesn't change because the lever arm (crank throw) is fixed. What does
change with a longer rod and less rod angle is the force vector. You
can gain very slight efficiencies with longer rods, but the torque of
an engine is primarily controlled, as CR correctly stated, with
stroke. Other things have influences, but stroke is the primary
mechanical factor.

Oh, and obviously, a longer rod does not increase stroke.