Thanks for the note.
I will try to ask some of my friends at Ford SVO to explain why and how the
rods make more power. If they are willing to explain, I will post it.
At 10:44 PM 10/4/98 -0700, Bob Palmer wrote:
>Thanks for this interesting post. As an experimental physicist, I also
>strongly believe in "real world" confirmation of theory. Nothing pleases an
>experimentalist more than disproving a widely accepted theory. Of course,
>then the challenge is to develop the correct theory. However, in the case
>at hand I have seen neither data nor any convincing theory to explain
>higher output from longer rods. And, as you say, "even turbine engines,
>produced to far closer specs than auto engines, do not make the same power
>at birth...they have to be "adjusted" to a set standard." So, simply
>comparing two engines nominally equal except for rod length would not be
>enough to establish a solid case. And, if fact, it is impossible to just
>change rod length without making other changes, like relocating the wrist
>pin. On the other hand there is a good theoretical foundation for the
>benefit of longer rods in terms of reducing stress, and this alone would
>justify their use in high rpm motors.
>I understand that at least some of the newer motors being built have quite
>high rod length to stroke ratios; e.g., the Ford 4.6L modular motor. I'm
>willing to bet there are at least one or two engineers at Ford that could
>tell us quite a story on this subject. Unfortunately, they may consider
>this to be "proprietary" information and, therefore, be unwilling to
>divulge it to the masses. What a pity. It would be nice to know the
>reason(s) for this recent trend toward longer rods. Let us know if you hear
>any good stories in this regard.
>At 10:18 PM 10/4/98 -0500, Ray McCrary wrote:
>>I don't pretend to play an engineer on TV, but I know that the SVO pistons
>>have a relocated pin in them that means that you have to use a longer rod.
>>I know that ALL of the major Ford engine builders (including Ford
>>Motorsports) that I contacted used the longer rods and claimed PRACTICAL
>>horsepower and reliability gains by doing so.
>>I remember the discussion you refer to; I was party to it, and after
>>reading MANY postings by a great many people who seemed to know something
>>that I didn't, I gave up and began to contact people with ACTUAL experience
>>in making reliable horsepower.
>>I suspect that the math majors are leaving some variable out of their
>>calculations....either that or the dynos are wrong, and a lot of people who
>>work at Ford are wrong.
>>I doubt that "convenience" of production has much to do with the production
>>of special components for all out race engines.
>>As to "matched" engines, let me say that even turbine engines, produced to
>>far closer specs than auto engines, do not make the same power at
>>birth...they have to be "adjusted" to a set standard.
>>In short, theory is interesting, but I'll take real world knowledge anytime!
>Robert L. Palmer
>Dept. of AMES, Univ. of Calif., San Diego