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Shyguy · 09-06-2010, 08:36 PM

This is the setup I have. It is a '92 GMC K-3500 with a 454 and 4L80e. I pull a 8400 pound 5th wheel travel trailer.

If I run right at 58 mph using a deflector wing on the top of my truck while towing I get an average of 8 mpg. If I am running empty the best it has ever got was 12.5 mpg running 58 mpg.

My truck is stock except for a performance chip. It has 4.1? rear gears.

454s are not known for fuel economy.

You could put a gear vendor over-drive behind the transmission, but that gets pricey and it takes a long time to recoup the cost of the over-drive with increased gasoline mileage.

09-06-2010, 08:36 PM	#6
Shyguy Junior Member Join Date: Dec 2006 Location: Southeast Missouri Posts: 2,436	Re: Help me get better fuel mileage This is the setup I have. It is a '92 GMC K-3500 with a 454 and 4L80e. I pull a 8400 pound 5th wheel travel trailer. If I run right at 58 mph using a deflector wing on the top of my truck while towing I get an average of 8 mpg. If I am running empty the best it has ever got was 12.5 mpg running 58 mpg. My truck is stock except for a performance chip. It has 4.1? rear gears. 454s are not known for fuel economy. You could put a gear vendor over-drive behind the transmission, but that gets pricey and it takes a long time to recoup the cost of the over-drive with increased gasoline mileage. __________________ '67 Chevy C-20 short stepper - build complete, 454/SM-465. '75 C-30 Single Cab DRW-350 small block/NP-435. '77 GMC-6500 Dump Truck, 427 Tall Deck. '92 GMC K-3500 Duallie, 454/4L80E.