Around 5-8 mpg depending on your gearing. Personally I'd prefer the 454 is you do much hauling. The only reason being in that with it being a 3/4 ton, the 454 and its bigger torque curve, it doesn't have to work as hard. The downside is that you trade off fuel economy.
Don't go meddling in the affairs of Dragons for you are crunchy and quite good with ketchup.
I have a 2000 3/4t crewcab 454 vortec, stock tire size, auto transmission and 373 gears and normally get between 11-12mpg running empty. To date I have installed a K&N cold air intake, true dual exhausts and JBA shorty headers to try and increase the fuel economy with little or no results. I have also purchased the hypertech econ progammer and it had very little effect on the fuel economy. I would be interested in any suhhestions you or memebers of the forum might have. Also there is a shop in South Dakota that does custom tunes on trucks and I was wondering if anyone has had any favorable results from this type of tune.
Chevrolet/GMC, Racing, Recreational Forum Moderator
Join Date: Apr 2009
I was basing my previous opinions on a 99 2500 with a 5.7 Vortec that I used to have. I then went to a 98 with a 454. They got real similar mileage and of course the big block had more power. I recently picked up a 98 2500 with a 5.7 and it is getting decent mileage. The motor is fresh so that is helping I am sure. I drove down to Atlanta empty and got 16 MPG. I hooked to a car trailer with another trailer on top and came back at 14-15 MPG. It doesn't have quite the power as the 454, but for what I haul it does fine. The 2 trailers on top of each other were hardly noticed back there at all. It was probably only a 3000 pound load so it shouldn't have been noticed.
__________________ 2003 Chevrolet Tahoe 4X4 5.3 2002 Chevrolet 2500HD 4X4 8.1 - BlackBear Tuned