mpg on 04 sierra

Discussion in 'Performance & Fuel' started by dave13net, Dec 20, 2013.

  1. dave13net

    dave13net Rockstar

    hi, have a 04 sierra 1500 4x4 extended cab with the 5.3. notice the fuel mileage seems to go down in winter with heat on(14). seems if i turn off heat it
    gets a little better. in warm months it gets better mileage.(16)\, except when i use the ac. took 800 mile trip south mid november and averaged close to 19.
    plugs and wires (mallory) done about a year ago,new air filter 1 month ago. don't drive it hard, i keep my foot out of it as much as i can, but cold seems to make it worse. thanks, any help would be appreciated.:neutral:

    p.s. any ideas on where to get some performance parts for engine(cam,lifters, comp.chip):gasp:
  2. shaggy08xr

    shaggy08xr New Member

    I have noticed the same affects with my 04 Silverado but I have noticed a decline in mpg's regardless of whether the heat is on or not. has lots of good stuff for these trucks along with jegs racing and these are very popular motors so parts aren't stupid expensive.
  3. dave13net

    dave13net Rockstar

    hi thanks for your reply,yep, summit and jegs, but is the block ls1,ls2,ls3????? or something else. heard them refered to 327 because actual c.i. is 323. strong engine
  4. BRB46

    BRB46 Rockstar 100 Posts

    My mileage also drops in the colder months but I figured it was the winter blend gas. I don't know if it has anything to do with heat being on. A/C will have an effect on mileage.
  5. TRPLXL2

    TRPLXL2 Epic Member 5+ Years 1000 Posts

    Your engine is technically an lm7 or lm33
    Ls1 is a 5.7
    ls2 is a 6.0
    ls3 is a 6.2

    I bought all my performance goodies at summit racing
  6. dave13net

    dave13net Rockstar

    ok, thanks for the info. kinda thought L something, what's the difference between the Lm7 and Lm33 ?

    99'HEARTBEAT MODERATOR Staff Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    The is Difference is the LM7 is a Cast Iron Block W/ Aluminum Heads, and the L33 is a Aluminum Block and Heads.

    LM7.....The Vortec 5300 LM7 (VIN code 8th digit "T") was introduced in 1999, and can be considered the "garden variety" version of the Generation III 5.3 liter V8's. The 1999 LM7 engine produced 270 hp (201 kW) and 315 lb·ft (427 N·m), 2000-2003 engines made 285 hp (213 kW) and 325 lb·ft (441 N·m). The 2004-2007 engines made 295 hp (220 kW) and 335 lb·ft (454 N·m), it has a Cast Iron Block and Aluminum Heads.

    L33....The Vortec 5300 L33 (VIN code "B") is an Aluminum Block Version of the LM7, and was referred to as the Vortec 5300 HO in marketing materials. How ever it should be noted that the L33 uses a flat top piston from the 4.8L instead of the standard dish piston found in the LM7

    EDIT.....I would add that there are Now 10...5.3 Liter Vortec Engines.....LM7 / L59 / LM4/ L33 / LH6 / LY5 / LMG / LC9 / LH8, and the New 2014" L83 EcoTec 5.3 Liter.
    Last edited: Dec 21, 2013
  8. dave13net

    dave13net Rockstar

    thanks.. what about a cold air intake, always heard that they are worse because they suck in the hot air from the engine
  9. dobey

    dobey Epic Member 5+ Years 500 Posts

    If you're getting hot air from the engine bay, it's not a cold air intake. The factory intake setup is cold air. It draws in air from the fender well, not the engine bay. The main problem with the factory intake setup is the intake tube between the filter housing and the throttle body. But changing it isn't going to give you any real MPG boost. You might get 1 MPG if you're extremely lucky with it.
  10. sierra11

    sierra11 Rockstar 100 Posts

    There isn't really a one performance part under $800 that's going to give you huge gains in the HP, Torque, and MPG categories. You have to get a set up like a new intake tube/filter then maybe and exhaust and then a custom tune. When you put at least two of those three together you'll start seeing gains. I went with the intake tube/filter with a custom tune from BlackBear and they have helped a lot

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