Modified engine crewcab gas mileage?

[Nelsonic]

I have an 89 3500 crew 4x4 with an HT 502 currently running 33s with the factory TBI and th400. I get 9 MPG. I’m about to upgrade to a ProFlo4 fuel injection and a 4l80e. Mainly to drop the rpm at highway speeds but hopefully I’ll squeeze another couple of mpg out of it.

 

[Matt69olds]

Can you tell me, PLEASE where the gas is getting cheaper..........not here in podunk Idaho!!!

Or central Indiana! Or Michigan, Ohio, or anyplace my recent travels have taken me.

 

[TotalyHucked]

It's been creeping down slightly here in Ga

 

[Bextreme04]

I have an 89 3500 crew 4x4 with an HT 502 currently running 33s with the factory TBI and th400. I get 9 MPG. I’m about to upgrade to a ProFlo4 fuel injection and a 4l80e. Mainly to drop the rpm at highway speeds but hopefully I’ll squeeze another couple of mpg out of it.

I'd avoid the ProFlo... I've heard nothing but bad things about their computer and the programming ability of it. Probably cheaper and easier to put a holley BBC manifold on it and run factory P01 or P59 ECU. You should be able to get a throttle body, pedal, wiring harness, and computer for dirt cheap from a junkyard and then just buy the intake, fuel rail and injectors from any speed shop like Summit or Jegs. The P01 or P59 will run the 4L80 just fine and you'll have tons of support available with factory GM parts at that point.