Thread: Cubic Inches vs Liters

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While we are having fun, let me recall another adventure with metric units in the SAE world. I use metric units every day in Chemistry so when I actually bought a brand new 1973 Vega two door wagon I thought why not get a few frills so I paid an extra $180 for the "Rally Pack" option. When I took delivery of the new Vega (a very nice Fisher body style, but let's not talk about the aluminum cylinder walls) I found the "Rally Pack" consisted of a thin decal pin stripe on the sides AND best of all, a DECAL on the speedometer showing Kph alongside mph! WOW, a $180 decal! Anyway from that decal I figured that 1 mile = 1.6093 kilometers, so 100 Kph is about 62.1 mph, and yes a kilometer is smaller than mile. Regarding the case of 11 fingers, there is a recent TV ad where a guy has 6 fingers on each hand for a total of 12 fingers and supposedly he gets more office work done. Anyway it is clear that there is great resistance to metric units in the U.S. and my favorite suggestion is to keep all the measurements actually the same as the SAE sizes and just change the blueprints to read the sizes in metric! The only sanity to it at all is that as far as I know the metric folks do agree that 1.0000000 inch = 2.54 cm with no further decimals needed. The same sort of problem occurs in science where NIST/NBS routinely refines the numerical values of basic physical constants about every 10 years using a least-squares fit of all the constants to all known physical data. In Theoretical Chemistry this caused severe problems back in the 1930-1940 era but has been solved by defining every physical unit to be "1" in terms of the formulas so that as new values were updated only the algebraic formulas were needed to relate to the real world and this has worked out very well using what are called "atomic units" so modern 2005 calculations can be directly compared to calculations from the 1930s even though the values of the constants have been updated several times. Not to offend any of our friends in France (Viva LaFayete!) but you may recall that the meter was supposed to be exactly (1/10,000) of the circumference of the Earth at the equator, cut into a piece of metal kept in a temperature controlled case in Paris, BUT (Oh Oh!) they didn't have the right value for the Earth's circumference, SOOOO the meter is totally arbitrary based on an error! Too late now because the meter has been redefined in terms of laser wavelengths and adopted as an international standard. So the king's "foot" = 12 inches and maybe 1" is the king's thumb knuckle and maybe the Biblical Cubit is the length of an average forearm but you got to start somewhere and now with lasers length has been refined to many sig. figures. The worst cases are the need of Chemical Engineers to carry around pocket tables of conversion factors, but probably the several systems of units in electrical measurements are the most difficult but I like "atomic Units" which by the way define 1 bohr =0.529177 x 10^-8 cm (this value is presently under revision but the 0.5291 part is pretty definite) so there we are back to metrics, but in "atomic units" all the units are "1" times the formula for whatever is being measured, I like that system but for cars I guess all I need is 1.6093 Km/mile, 946 cc/qt. and 61.02374409 cu in/L or roughly 61.024 cu in./L.

Don Shillady
Retired Scientist/teen rodder