It is my understanding that longer rods and shorter pistons is not what is
making the power alone, it is designing a cam to take advantage of the greater
piston dwell at tdc and other variables. So if they had put a cam in the motor
that was designed to work with that combo I'm sure it would have made more
power. I have not seen the article, so I don't know what they had before the
longer rods/shorter pistons. As Barry has made the point a builder going from
stock Triumph rods and stock sized pistons will see a great reduction in weight
than say light aftermarket stock lenght rods and aftermarket stock sized
pistons. The latter seems like the case in the Hot Rod article. As Smokey
Yunick said "Use the longest rod you can fit in a motor." Also a forum
(www.speedtalk.com) I frequent with some HUGE names in the engine builder
circles had a thread on rod ratios. They basically resolved that it's a bunch
of bs, and to follow Smokey's motto.
barry rosenberg <email@example.com> wrote:
I understand the new Hot Rod magazine issue has an article on longer
verses shorter rods. They built an engine and swapped rods and pistons only.
They found no power difference. I have not read it yet, but I must assume
they had the rod/piston combinations weigh the same. I use longer rods in my
TR4 motor so that I could reduce the piston size, weight, and friction. This
should provide more rear wheel horsepower. So far it seems worth it. Who
else is doing this to get rid of that huge TR4 piston? Barry
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