27.5 mpg from '05 Suburban

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by chrisreed82, Mar 30, 2013.

  1. SupplySgt

    SupplySgt Rockstar 4 Years 500 Posts

    My 96 only had 1 airbag actually with those cupholders. Only way I can tell the 95 and 96 apart without popping open the hood was to look at the redline. 4500 on the 350 TBI and 5k on the Vortec 350. No clue on the 305s though. I don't mind gearing down when pulling a load, but that thing will struggle to pull 5,000+ lbs at highway speeds.

    My Camaro is a 73. Progress has been pretty slow lately though.
  2. gpeterson1968

    gpeterson1968 New Member

    Wow wish my 09 would get that I'm lucky to get over 20 on the highway. Mixed is between 15 and 16.
  3. joshuaT

    joshuaT Rockstar

    I just drove to and from St David, AZ from Las Vegas, NV and I got great gas mileage in my 4x4 z71 burb. How is that possible I get better gas mileage in this vehicle than in my S10 blazer? It's so awesome to get that kind of mileage so both me and the wife were impressed.
  4. blackburb

    blackburb Rockstar 100 Posts

    Have you checked the timing recently? My '94 4x4 with 3.42 and 157k was a gutless turd until I found the timing was retarded almost 13 degrees. Now it pulls my 30' Jayco (6000+ loaded) no problem at all. The difference was like going from a v6 to a v8. I was shocked how out of time it was and still have no explanation for how it got that way.
  5. SupplySgt

    SupplySgt Rockstar 4 Years 500 Posts

    You know that actually makes sense. It pulls fairly hard from 2500-3500 RPM but below that is totally gutless. I would still like to at least go Tuned Port at some point (the 305 TPI puts out the same power as my TBI and the 350 TPI is way more powerful. But this could at least help out in the meantime.
  6. K15 Blazer Guy

    K15 Blazer Guy Member 2 Years 100 Posts

    i think this is the main reason
    245/75 R16
    those are small tires dude lol

    big tires look awesome but you sure pay for them.... =(
    did '05 start that selective clynder BS? or is that newer?
  7. pmf608

    pmf608 Epic Member 5+ Years 1000 Posts

    Depending on your gear ratio in your axles, you can't always get under 1500rpm though. In my old silverado with 3.42 gears and the 4.8 engine, I would run about 1800rpm at 65-70mph. To go the same speed in my Avalanche with 4.10 gearing, I'm well over 2000rpm. Mix that with a heavier truck and 4x4, and I'm lucky to get 20mpg between 65-70mph. In the silverado I once got 25mpg on the uphill part of a trip through the mountains, averaging about 75mph. Both of those are with the same 20" rims and both with a performance tune. In the winter, it's a different story though for both. Grippier tires, cold weather, and winter blend gas sure cut it down.

    BUT, with the added weight of my truck, the 5.3 has extra power to balance it out over the 4.8 and the 4x4 shouldn't cause that much of a decrease, so I think gear ratio and the increase in rpm at any speed has a huge effect on fuel economy. It also changes the performance drastically. With 4.10 gears, the avalanche is better off the line and better for towing than the 3.42s in my silverado, but when I go to pass people on the highway I don't have the power with the 4.10s. The silverado with a 4.8 and 3.42 gears would run 100mph+ in second gear and pass people now problem with quick highway acceleration. The Avalanche with 4.10 gears is slow to accelerate on the the highway and takes more time to pass people.

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