4.8l With 35'' Atz Gear Change

[XJ96]

I owned a 2009 sierra 1500 crew cab with the 4.8L

 

My setup is

 

Airaid CAI

JBA headers

Hi flow Cat

magnaflow dual exit

6'' Fabtech

35'' ATZ

gear 3.42

 

My question is

witch one is the best for power and fuel economy the trucks it's my daily drive

 

stock 3.42 at 65MPH the RPM is 1714

35'' 4.10 at 65MPH the RPM is 1810

35'' 4.56 at 65MPH the RPM is 2013

35'' 4.88 at 65MPH the RPM is 2154

 

stock 3.42 at 75MPH the RPM is 1978

35'' 4.10 at 75MPH the RPM is 2088

35'' 4.56 at 75MPH the RPM is 2323

35'' 4.88 at 75MPH the RPM is 2486

 

do not forget my engine is the 4.8

[rodram]

... not sure of your question here...

 

but for fuel economy the lower the engine rpm, then the better highway fuel economy, keeping the engine rpm in the 1800-2000 range while cruising is likely optimum, and anything over 2000-2200 rpm then you are going to noticeable lose fuel economy

 

and for off-the-line torque, the higher the gear numbers the quicker the truck will be

 

... this might suggest that the 4.10 gears would be suitable for your needs

[Stevens03]

4.56's would be the best choice