GreaseDog
Pickup Artist
I hate to be the barer of bad news, but these trucks can't do much better than 18mpg with out a lot of work. they trucks are just too heavy, and push too much air down the highway. I just finishad installing an LT1 out of a WS6 bird, all it is doing is 14 to 16. I was hopping for 18 to 20. A good tuneup and fluids change will help a bunch. the truth is - most aftermarket goodies will help millage little if any. but first thing to do is prove if your odemeter is corect or not. if it reads less miles tour math will be tainted.
not true at all... i pulled 20mpg out of my 92 C1500 and never touched the engine or the ECM programming.
92 C1500
5.7/700R4
3.42 gears/open differential
225 75 16 tires on 16x8 aluminum wheels
Flowtech 11504 shorty headers, 11504Y y pipe, mandrel bent 3" single exhaust through a Flowmaster 40 series, full tailpipe exiting in the stock location.
K&N CAI
plugs gapped at .055"
full tune up using all AC Delco parts.
wasn't that hard at all, and the truck still had enough pep that it was fun to drive WHILE getting 20mpg.