can anyone tell me what the sweet spot is for my 2005 Chevy 3500, Duramax engine, 4X4 Dually Crew Cab, long bed with auto trans and 3.73 gears. I know the sweet spot to run my 2003 Harley is 53 mph for the best fuel economy and all around performance, not saying I run her there but that is the best spot for the bike if'n I want to get the best mileage for my $. I was just wondering if anyone new where the best spot for my truck is in regular mode and also in tow/haul mode, there must be a certain RPM for the best fuel economy empty and towing my 9000# TT. If anyone has this info I would appreciate if they were to pass it on to me so I can be a educated consumer. Thanks:help:

I'd say right after the TC locks in 5th and keep it there when empty. Most of your economy is dependent on how heavy you accelerate and how far above 2Krpm you go. When towing if you lug it too much you'll always be dropping into lower gears and killing your mileage so I'd keep it at 60-65mph while towing as long as it's safe to go that fast.

2000 rpm all around works best for me, drops fast the higher I go. That equates to about 63 mph on my truck.

I find 60 about right towing or empty my fiver weights about 13000 lbs has a gross of 14600lbs

about 1950 (just on the edge of 2000) works good form me in my 05 dually. Thats very close to 65mph. I can run between 60 - 65 mph & can save some but since I hotshot, I need to get to where I am going & running 65 is not really enough to make alot of difference vs the time.

58 mph with 3:73 gears and 2:65 tires

1600 rpm is optimum.but it dont pull good there

i like to watch my EGTs they seem to show if the engine is getting fuel i mean i can see it go up before my RPMs even move , i try to keep it a little under 800

i like to watch my EGTs they seem to show if the engine is getting fuel i mean i can see it go up before my RPMs even move , i try to keep it a little under 800

That's what its all about... EGT is a good source of fueling info...

1600 rpm is optimum.but it dont pull good there

Where do you get this number from? Is this your experience, or do you have more info that might be useful to know? Just curious...

Peak Torque is at 1800 rpm per GM; about 60 mph in top gear.