How much MPG loss going from 2.73's to 3.73's?
Thread Starter
Senior Member
Joined: Apr 2000
Posts: 682
Likes: 24
From: MidWest
Car: 91 RS/ 99 T/A/ 72 Vette/ 02 Z28
Engine: LSx/ Dart400
Transmission: M6/ M6/ TH400/ 4L60E
Axle/Gears: 4.10's / 3.08/ 2.73
How much MPG loss going from 2.73's to 3.73's?
How much MPG loss going from 2.73's to 3.73's?
Car averages 24-25mpg daily driving.
Car averages 28-30mpg on highway.
Best highway mpg was 32.5mpg
What mpg should I expect if I go from 2.73's to a 3.73 Auburn posi?
Details are I have a 4th Gen TCS rear end I can't use in my 99 T/A because the 99 T/A doesnt have TCS.
Thoughts?
Thanks
Car averages 24-25mpg daily driving.
Car averages 28-30mpg on highway.
Best highway mpg was 32.5mpg
What mpg should I expect if I go from 2.73's to a 3.73 Auburn posi?
Details are I have a 4th Gen TCS rear end I can't use in my 99 T/A because the 99 T/A doesnt have TCS.
Thoughts?
Thanks
Member
Joined: Oct 2002
Posts: 386
Likes: 0
From: Edmonton AB Canada
Car: 86 Firebird
Engine: 355 4 bbl
Transmission: TKO 600
Axle/Gears: 3.73 L/S
You might want to factor in a deduction in fuel economy of about 5 - 10% "hooligan losses" due to the additional enjoyment of footing the throttle.
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Joined: Jan 2000
Posts: 20,981
Likes: 11
From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
It will depend somewhat on your cam, I didn't lose any mileage at all going from 2.73 to 3.54 because my cam is happier with a higher cruising RPM.
Joined: Sep 2001
Posts: 701
Likes: 2
From: Clinton, IA usa
Car: 1984 Firebird
Engine: 350 Terminator EFI
Transmission: T56
Axle/Gears: 4.10
i went from 3.23 to 3.73, its a smaller jump but i also noticed a minimal decrease in mileage, when i am just driving. in a hard running situation its noticably worse, due to the secondaries opening, as with Apeiron my cam prefers a higher cruise rpm
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