Ray, et Listers,
Careful Ray, the Mayf is kicking ass and taking names today, and you may be
his next victim. Actually, it's kind of nice to have someone else playing
the bad guy for awhile.
I have the article you refer to, plus several more that argue this issue
both ways. Some say long is better, some (a minority) say short is better.
Now, of course, how could they print any of this if it wasn't true?? In
spite of using vague references, circular thinking, and just plain wrong
facts, I guess we're supposed to believe them because they are the
"experts" who also happen to know how to write (or at least know somebody
who does). Now understand me here Ray, it's not you I'm taking to task, but
the purveyors of small doses of fact wrapped liberally with snake oil.
For example: "Use of longer connecting rods also increases the time the
piston stays to TDC, allowing greater latitude in timing.(*less detonation)
". Now I'm sure Mr. Wilson has lots of data to support his assertion that
timing is less sensitive. (NOT!!) And is he implying that we can't have
timing accurate enough to get the optimum power out of a short rod motor?
I'd sooner believe the longer, therefore more efficient, combustion
argument. That is, until you actually calculate the percentage difference
in hang time between, say, a 1.696 ratio and a1.855 ratio.
Another example, this time of a falsehood wrapped in more B.S.: "At the
other end of the stroke, the piston hangs longer at the bottom, resulting
in complete filling of the combustion chamber.(*better use of the ram
effect of improved manifolding and camming)." Now here Mr. Wilson has it
just backwards. In fact, as you increase the rod length to stroke ratio,
the time near BDC actually DECREASES. (Hey, could I print it if it wasn't
true!!)
In spite of my criticisms, I do appreciate you comments. But, in the
meantime, I think we still have a ways to go before we get the real issues
sorted from the chaff on this question.
Bob
At 06:06 PM 10/5/98 -0500, Ray McCrary wrote:
>Hello all,
>
>Read an interesting article about the effect and theory of longer rods
>(center to center length) in the 302 Ford engine.
>
>Let me preface this by saying that this IS NOT applicable to you who are
>looking for cheap power out of a basically stock engine.
>
>The article was written by Kevin Wilson at ENGINES magazine, a Petersen
>Magazine home office in L.A. (a small rural area engaged in the manufature
>and sale of snake oil). Their phone number is 323-782-2000......in case
>you desire to contact them.
>
>"However, one of the shortcomings of the 302 is its relatively short
>rod-length-to-stroke ratio. Increasing that ratio through the use of
>longer connecting rods reduces piston side loading in the cylinder, thereby
>reducing friction, which contribute to durability. Use of longer
>connecting rods also increases the time the piston stays to TDC, allowing
>greater latitude in timing.(*less detonation) At the other end of the
>stroke, the piston hangs longer at the bottom, resulting in complete
>filling of the combustion chamber.(*better use of the ram effect of
>improved manfolding and camming).
>On Ford small blocks, longrod engines are also less sensitive to intake-
>and exhaust-tuning than stockers. The longrod setup increases torque and
>horsepower without increasing displacement."
>
>This article uses chevy rods (5.565 in long vs. Ford 302 stock rods 5.09
>in) to increase the rod length to stroke ratio from 1.696 to 1.855.
>
>Like everything else in engine building, no one mod is a stand alone thing,
>but for a serious engine, the longrod works.
>
>Regards,
>
>Ray
>
Robert L. Palmer
Dept. of AMES, Univ. of Calif., San Diego
rpalmer@ames.ucsd.edu
rpalmer@cts.com
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