gas mileage and gears question
07-21-2008, 01:44 AM
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gas mileage and gears question i got a 02 z28 a4 and at 70 mph its only turning about 1700 or 1800 rpms,i was wondering what gears i might have in there (they are stock)with those gears i ran only 9.10 in the 1/8 mile , but i get about 22mpg................i also want to know the lowest gears i can put in and still get 16 to 17mpg.....also with those gears what kind of time improvement i should see....as the car sits
07-21-2008, 07:56 AM
#2
Your data indicates 2.73s',3.23s' would be 2200/2300 at 70mph.Your 22 mpg would be for overall? 2.73s' are rated at about 30 mpg for freeway driving.
In Sept.07,I went from A4 3.23s'(GU5 option) to A4 4.56s'.
Freeway RPM in 4th convertor locked
-2700 RPM at true 60 MPH
-2875 RPM at true 65 MPH
-3075 RPM at true 70 MPH
RPM were read off factory dash tach and 'true' MPH were established by timing time between mile markers.
MPG seemed strangely good,for 4.56s',driving around locally and was proven to be incredible on a long trip.I did a Cleveland,Ohio to Tampa,Florida and back with 4.56s'.Having done this trip 8 times before in my Z with the 3.23s',I would get 24.5 MPG staying with traffic and 25.5 observing the speed limits.It's a 1070 mile trip with the same route(s) taken every trip and it provided me with good data with/for the 4.56s'.With the 4.56s' I got 21.5 MPG keeping up with traffic and 21.9 MPG observing the speed limits.Theoretically with the mechanical ratio change,it should have been in the 17-18 MPG range.
At the strips,Norwalk and Thompson,it was consistent 13.7x's with the 3.23s',4.56s' gave me consistent 13.2x's.
I don't consider returning to 3.23s' as the 4.56s' are too much fun on the street.
Would I recommend 4.56s',NO,but I'm old school from the 60s' and 70s' when torque and gears ruled the streets.
In Sept.07,I went from A4 3.23s'(GU5 option) to A4 4.56s'.
Freeway RPM in 4th convertor locked
-2700 RPM at true 60 MPH
-2875 RPM at true 65 MPH
-3075 RPM at true 70 MPH
RPM were read off factory dash tach and 'true' MPH were established by timing time between mile markers.
MPG seemed strangely good,for 4.56s',driving around locally and was proven to be incredible on a long trip.I did a Cleveland,Ohio to Tampa,Florida and back with 4.56s'.Having done this trip 8 times before in my Z with the 3.23s',I would get 24.5 MPG staying with traffic and 25.5 observing the speed limits.It's a 1070 mile trip with the same route(s) taken every trip and it provided me with good data with/for the 4.56s'.With the 4.56s' I got 21.5 MPG keeping up with traffic and 21.9 MPG observing the speed limits.Theoretically with the mechanical ratio change,it should have been in the 17-18 MPG range.
At the strips,Norwalk and Thompson,it was consistent 13.7x's with the 3.23s',4.56s' gave me consistent 13.2x's.
I don't consider returning to 3.23s' as the 4.56s' are too much fun on the street.
Would I recommend 4.56s',NO,but I'm old school from the 60s' and 70s' when torque and gears ruled the streets.