<VV> Fuel mileage

[FrankCB at aol.com]

Right On, Clark!
Further on the "overdrive transmission", the important thing is the OVERALL 
 ratio from engine to rear wheels which takes into account BOTH the 
transmission  ratio in top gear and the axle ratio.  Most of the Corvairs have the 
3.55  to 1 axle ratio and 1 to 1 top gear transmission ratio giving 
something like  3000 engine rpm at 60 mph.  In contrast, my 1995 "Dustbuster" Trans 
Sport  Minivan has a 3.06 axle ratio and an overdrive ratio (less than 1 to 
1) in the  4th speed of the 4T60-E auto trans.  The result is only 1800 
engine rpm at  60 mph.  This gives me 26 to 28 mpg on long highway trips with an 
engine  (3.8 liter) that is 40% LARGER than the Corvair's 2.7 liter engine.
GM did have a 3.08 axle ratio that they put out briefly to achieve better  
mileage for the Economy Runs in the 1960s.  That would certainly help  
improve highway mileage.
In addition, a modern EFI engine has computer-controlled feedback from the  
exhaust gas oxygen sensor that continually adjusts the EFI to maintain the  
correct fuel to air ratio giving great mileage.
But perhaps the GREATEST influence on highway mileage is due to the "nut  
behind the wheel".  I'm continually amazed at the number of people who come  
up behind me in traffic, pull out and pass me and then race to the next 
traffic  light where they have to JAM on their brakes to stop at the light.  
Many  times, by the time I coast up the to the light, it has turned green and I 
can  get through it WITHOUT stopping.  Guess who's getting the better gas  
mileage!!
 
Frank "tightwad" Burkhard
 
 
In a message dated 4/16/2011 7:54:02 A.M. Eastern Daylight Time,  
chartzel at comcast.net writes:

Harry  Smith wrote about using a Corvair as a daily driver.  I doubt  a
Corvair is going to get 20 MPG in the city.  I have never gotten  more than
22 MPG in any Corvair I ever owned.  Corvairs have two major  drawbacks for
good fuel economy:  carburetors and no overdrive.
If  you are looking for good economy get a small fuel injected car with  an
overdrive transmission.
Clark  Hartzel

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