Personally i would not put in a stroke much shorter than the valve gear
will rev..If the stroke allows for a 11,000 redline and the valve gear
will only go to 8000 then you are giving up a ton of compression usually
to keep the piston speed down to a point so low that you have very
little inertia in the intake charge.. and a rod ratio that is so long
you might never even see a torque peak.. ya gotta either have some
leverage on the crank or enough rpm to make the small push on the piston
happen very often...
to me that rod you are running is mighty long...but I bet the side load
on the walls is non-existant..
Dahlgren
Jane McMeekin wrote:
>
> Talking about a "favorite" Class "D" engine size makes me wonder if an
> ideal bore/stroke ratio exists in terms of maximum power potential. Big
> bore, big valve condition aside, should we expect a significant power
> differential between a 4.25"x2.65" ratio and a 4"x3" size? Is the
> primary reason for favoring the larger bore due to "better breathing" or
> do piston speed, friction, and other variables enter into the equation?
>
> Incidentally the 3 Liter Buick has a 3.52x2.35 bore and stroke with 6"
> rods. Our "fanny dyno" says its doing all right but maybe it could be
> better.
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