In article <3B939946.234E18F5@worldnet.att.net>, Bob Sykes
<stan.part@worldnet.att.net> writes
>Some interesting numbers in this thread. Certainly the
>~50mpg number is under ideal circumstances, but possible.
>
>A starting point for the YCV (Yank Conversion Factor)
>should be on the order of 0.777 though. This is based
>on 0.833 for Imperial/U.S. gallons and 0.933 for
>3.63/3.89 final drive ratios.
Depends what you are trying to do. If you are trying to compare the
efficiencies of UK and Federal-spec cars, that's fair enough, but if you
are trying to ascertain the maximum achievable mpg of any Spit, you
should leave the drive ratios out of it.
>
>Add to this-
>
>The (dry) weight difference (on the order of):
>U.S. = 799kg.
>U.K. = 763kg.
>Depending on the source, options and model year.
>(Tom, you forgot the heavy front number plate plinth ;-)
And what is the difference between the average weight of a Spitfire
driver in UK and US? I'm a big chap - six foot tall, and
euphemistically "well-built" (14 stone 2 when last I got on a weighing
scales - that's about 198lbs in American money, or 88kg...) We here in
the Olde Worlde are frequently exposed to Touristicus Americaniensis
(the Common American Tourist) who appears to weigh about 350lbs in his
sock feet, and 500lbs fully dressed, including camera equipment and
tartan cap. On the other hand, the junk I carry in my boot must weigh
the best part of 50kg, including spare wheel/tyre, whereas I gather than
many US Spit drivers carry nothing more than a mobile 'phone and an AAA
card. :-)
Actually, joking apart, the weight of the driver, and the weight of the
stuff in the boot can and does make a terrific difference to the fuel
consumption figures of identical cars.
>
>It is harder to find a number to represent the mpg
>difference due to the "detuned" U.S. motor and it's
>attendant emissions kit, but it would be significant.
Natch.
>
>The drag coefficient is lowest with the hardtop on.
>Add a coat of wax and it's absolutely amazing.
>This obviously has more impact on mpg at higher
>speeds, and ultimately determines top speed.
>Around town, the added weight of hardtop and wax,
>probably reduce mpg.
It's probably the wax that's the killer. :-)
>
>FWIW I'm currently getting about 30mpg, city driving
>(U.S. spec car/gallon with SU HS4s and U.K. exhaust)
That sounds pretty good. Better than I'm managing, but then, I do have
a blown piston ring.
>and about 25 mpg, city driving with another U.S. spec
>car running Weber DGV/ 4-1 header.
>
>Of course (I can't resist) YMMV.
ROFL!
ATB
--
Mike
Michael Hargreave Mawson, author of "Eyewitness in the Crimea"
http://www.greenhillbooks.com/booksheets/eyewitness_in_the_crimea.html
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