[Land-speed] Tires,Mileage,etc/non LSR ?

[Ed Van Scoy]

The article was a good read Tom, thanks for passing iton. I am not an engineer
(or rocket scientist.... heck, I didn't evenstay at a Holiday Inn last night)
and it was written at a level thateven I could understand ;-) I didn't
understand the author'sdefinition of "normal gearing" however, as my vehicles
are geared allover the board, from my tow vehicle to the Corvette, which was
designedas a high-speed touring car. Likewise, I have numerous
transmissions(both automatic and manual) , some including overdrives, and some
witha 1:1 final drive ratio. My personal experience is thatperformance and
mileage are all over the board (as I would expect). Ithink "normal" is a poor
choice of words as vehicle application variesgreatly. No argument about
judicious use of the throttle..... Mydiesel tow vehicle gets several MPG
better mileage at 65 than 75....and 60 is even better if I could stand to go
that slow. I have no doubtthat on a level surface, 55 mph would yield better
mileage, especiallygiven the load I am pulling . I didn't understand the
author'sassertion that diesels do not hqve a throttle... unless he is usingit
in a different context than I - as a means of regulatingengine speed. As for
gages... my truck's "averageMPG" gage reads the opposite than slim's.... It is
very pessimistic,and I find i actually get better mileage. However, the
"gallons used"gage is very accurate. With an 84 gallon capacity, I find it is
usuallyoff less than a gallon at fillup.
Ed

-----Original Message-----
From: Tom Bryant [mailto:saltracer at awwwsome.com]
Sent: Monday, July 21, 2008 09:31 AM
To: land-speed at autox.team.net, BWANA343 at aol.com, 'Ed Van Scoy'
Subject: Re: [Land-speed] Tires,Mileage,etc/non LSR ?

Ed,

I don't doubt that what you say is correct. There are alwaysexceptions. I
don't claim to be a "Rocket Scientist", I wasreferring to a July 2007 article
from Motors Magazineby Mike Dale, "Meddle With the Pedal: Electronic
ThrottleControl." This article was part of recent Instructor Training that
Iattended for the CA Smog Program.

Quote.."Given normal gearing, the peak efficiency point for avehicle turns out
to be around 55 mph. The double-nickel speed limitwas not chosen randomly, but
rather with an eye to best results forfuel economy for the average vehicle.
For a givendistance traveled, fuel economy tapers off at both higher and
lowerspeeds. Holding a constant speed is an advantage, as it avoids both
theextra fuel needed for acceleration and the increased emissions thatoften
result from deceleration.

Not surprisingly, the sweet spot of engine efficiency is also thesweet spot
for emissions output."....This is a very interesting articlethat can be found
on line by going to http://www.motor.com/article.asp?article_ID=1179

Tom, Redding CA - #216 D/FCC

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