Please help

[H440exconfused]

I have just purchased tonight, a 2003 GMC sierra3500 4x4 dually with the Allison trans. I am picking it up in the morning. I didnt buy the deisel this truck has a 8.1L big block. After i bought it and i was on my way home all the time thinking it was a 454 big block. But now I am thinking a 454 is like a 7.4L or something, can someone tell me what cubic inches a 8.1L is or the Liters of a 454???


Thanks in advance, Mike

[H440exconfused]

Got it thanks

[JD400exrider]

Congrats on the truck. The 8.1 in a dually should get you about 10-12 miles per gallon. You better hope the gas prices go down.

How much more for the diesel.

[H440exconfused]

Originally posted by JD400exrider
Congrats on the truck. The 8.1 in a dually should get you about 10-12 miles per gallon. You better hope the gas prices go down.

How much more for the diesel.



I didnt want thew deisel, I am goning to lift this truck. Its not a daily driver just wanted it to use to haul the quads and to go to the dunes and up north.

So the mileage doent really matter to me at all or the fuel costs.

[H440exconfused]

By the way thanks for the mileage tip, i was kind wondering a little how much it got.

[JD400exrider]

The mileage tip is just a guess. The old 454's would get around 8-10 loaded or not on a dually So i am thinking you should get at least 10- 12. Who knows though. Lifting it with bigger tires will effect it some and it all depends how much tou have your foot in it. I would do some exhaust mods for better flow and a K&N filter. That will help with towing and mileage.

Good luck

I am getting close to 20+ mpg on my cummins. :D