I'm just curious if anyone has fuel economy figure for the vortec 350's and 454's in a k2500 style truck. Is there much difference?

 

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.

 

I have had them both and I decided to stay with the big block for pulling. My trucks compared like this -

99 2500 P.U. w/ 5.7 - empty 16 MPG, towing loaded 16' enclosed trailer - 11 MPG

96 2500 Suburban w/ 454 - empty 14.5 MPG, towing same 16' trailer - 12-13 MPG, and 11 MPG pulling our pontoon boat through the mountains (it's a freakin parachute back there)

I also had a 96 3500 dually that got the same mileage as the Suburban - I actually got 14.7 coming from Florida to SC unloaded.

As you can see there isn't much difference and the big block actually gets better towing. The huge difference is the power. The 454 seriously out pulls the 350 so to me it's a no brainer.

 

Too bad they stop making the big block!

 

WOW! I have a 95 HD3500 pickup with a lightly loaded utility bed and I am only getting 7 MPG. I better check things out. The truck is new to me.

 

You have a couple things against you - the 3500HD is a very heavy and you have a TBI motor. You might be able to squeeze a little more out of it, but not much.

 

I have a 1998 K2500, with the 5.7, and I get 14 MPG with no load.

 

I have a 1995 1500 extended cab 4wd 5.7L auto, and I get 23MPG with no load and I am having over fueling issues! Granted our galon in Canada is different to the USA.

 

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.

thanks jaeger

 

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.