What are things I can do to get better MPG?

[GreaseDog]

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.

 

[Playare]

Open or remove tailgate, less wind resistance. or get a bed cover. Its gotta help some, you can feel the difference on a windy day the truck doesn't move as much.

 

[Vigh_J]

vighj you get 350 miles to the tank with 38's and 3.73s???

Yes sir, right now im at half a tank and have 400km on the trip (248 miles)

 

[Klumpper]

in my 93 k1500 with 5.7, 3.73s, 4l60, and 265s I could regularly knock down 18 with the cruise set ~73, while not towing. Keeping the speed to 68 would bring it over 19, and when cruising northern mi with speeds ~60 I could break 20. The truck was maintained to a top, tire air pressures were closely monitored, and it got driven like an old man. No modifications, save for replacing the stock muffler with something off the shelf at the exhaust shop shelf when it rotted out. Towing (quad on utility trailer or enclosed 2 place sled trailer) would bring it to the ~14-16 range on the highway. This was when the truck had 110-150k on the clock. Mileage sharply dropped off when driving hard, or getting the engine speed over 2k rpm.

my 97 tahoe with 4wd and a 350 would only best out around 18.5-19. Towing a sled trailer it would do ~15, with OD on flat ground, 3rd in some hills. 3.42s, 245s, bone stock save the tune-up. Driving back-forth to work with patience I could get 17.5. My brother only gets 16 at best in it.

my '00 k3500 srw with a 350, 4l80, and 4.10's ALWAYS gets 12-13. Typically 12ish in the winter and 13, sometimes 14 in the summer. Bought the truck with 62k on it, has 85k on it now. Unloaded or towing just shy of 9klbs. 265/75s or 255/85s, (all corrected for), driving like an old man or foot to the floorboard, left in OD or locked in 3rd, it just doesn't care. I've even found driving in the city like a tool not breaking 40mph it STILL gets 12. I'm thinking the leak in my left side collector off the manifold has something to do with this, as once I clear out the long term fuel trims, it runs really good for a while, then back to normal. It's too rich at a warm idle. I REALLY need to fix this, but I'm currently over seas for work, which was hectic at best before hand. Making sure there are no exhaust leaks within 3 feet of the O2 sensors helps them read better. I need to log the voltages though, as I believe one of them is failing.

So, air pressure, maintenance, driving style in the lighter duty trucks, and check your O2 sensors.

 

[NotThatLow]

im getting 18-20 on highway with a 350 and 700r4 with nothin done at all. my gears are 3.73 also i cruise at 60-65 im getting ready to put in e fans, and a new exhaust now when i get off in to it i can litterly see the gauge falling lmao.

 

[Southern Pride]

I'm sorry but I just don't buy the tail gate thing. Its about as effective as a spoiker in my mind. You'd have to be going pretty fast for it to even start to take effect I just don't buy it. In my mind its all ab how hard, or less the engine is working to turn tires via RPMs...and also condition of the motor.

 

[borahshadow]

I'm sorry but I just don't buy the tail gate thing. Its about as effective as a spoiker in my mind. You'd have to be going pretty fast for it to even start to take effect I just don't buy it. In my mind its all ab how hard, or less the engine is working to turn tires via RPMs...and also condition of the motor.

With the tailgate up it creates a rotating "air bubble" in the bed of the truck which deflects the moving air stream that is passing over the cab past the end of the truck or in other words the highway speed air stream won't normally hit the tailgate. In some cases you can actually cause more drag by putting the tailgate down.

 

[Vigh_J]

With the tailgate up it creates a rotating "air bubble" in the bed of the truck which deflects the moving air stream that is passing over the cab past the end of the truck or in other words the highway speed air stream won't normally hit the tailgate. In some cases you can actually cause more drag by putting the tailgate down.

Yeah they "BUSTED" this myth on MYTHBUSTERS! Tailgate down is no better.

 

[Southern Pride]

Aha I knewz it

 

[Playare]

You learn somethin new everyday I suppose lol.