RE: miles per gallon
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RE: miles per gallon - 4/14/2008 8:35:03 AM
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HummerGuy
Posts: 6669
Status: offline
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I didn't realize the H2's had such crappy gas mileage. Sheesh.
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RE: miles per gallon - 4/16/2008 10:36:46 AM
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hummer.dad
Posts: 6
Joined: 8/21/2006
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I have an '06 SUT w/25k mi. I get 12.8 in town according to the DIC. If I check actual mileage I'm around 12.0. That is with a light foot and only getting into when needed. Highway I've seen 13-15 depending on conditions and speed.
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RE: miles per gallon - 4/16/2008 8:44:41 PM
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Terminator
Posts: 16
Joined: 2/24/2007
Status: offline
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When I originally bought my H2 SUT my mileage was about 10.9 (combo driving) but now after a few small mods my H2 computer average is 13.4, tracking mileage and fuel I have figured my average at 13.3. Not to much difference to quibble about. I can tell you a number of things I did that will help:
1. Remove the cross bars off the roof (easily remove and installed as needed)
2. You can get a little more if you remove the air deflector on the sun roof (don't do this if you like to open the sunroof as you will have a hurricane in your H2). (2 screws and 2 clips, Items 1 and 2 will just about remove all of the air noises at cruise)
3. Add a cover to the rear of your SUT (if you have the factory cover your golden, an expensive tonneau cover will do just fine).
4. Replace the original thermostat with a 160 degree, you engine will run cooler and I believe the computer will give you additional timing advance increasing your mileage. (I used an assembly available for the late model Corvette's, I noticed a slight improvement in performance and slight mileage gain, you will also see a lower transmission temperatures)
5. I removed the rear tire carrier and installed a custom tag bracket for the license tag. (I have the air compressor and repair kit if I get a flat, inexpensive and available at any discount auto parts). The spare carrier is a pain in the ass if you want to drop the tailgate and carry anything, considering I just about live at Home Depot and Lowes this is a great mod. The Carrier is VERY HEAVY and creates additional air drag) You have 2 choices on this, simply remove both the tow hooks (which also holds on the carrier) and place plastic filler caps in the place of the bolts or upgrade your tow loops to stainless, additional expense but it looks great as well as eliminating the spare tire clutter. Clean mean look! The tag bracket I picked up of eBay cheap.
These items add considerable drag and weight to the vehicle and if you don't use them simply remove them. I also clean the air cleaner every oil change (compressed air cleans them up just fine) and use Mobil 1 products in the engine, transmission and x-fer case. These changes cost little but provide good results as well as protect your investment. Overall my H2 is quieter (much less air noise at cruise as well as drive train noise) and is more usable (rear bed) than it was when I bought it. I also love to hear my neighbor complain about the mileage on his Ford Excursion. (If you think your H2 is bad on fuel buy one of these if you really want to see what bad mileage is all about)
Regards,
Dan
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RE: miles per gallon - 4/19/2008 8:22:22 AM
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h2guy8878
Posts: 45
Joined: 1/22/2008
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dude i have to run 93 octane in my 08? how do you know?
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RE: miles per gallon - 4/19/2008 8:30:23 AM
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h2guy8878
Posts: 45
Joined: 1/22/2008
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dude i just read my owners manual it says pretty much to experiment, you can ru 87 but if you beat on it you havr to rum high test, F*CK that sucks $$$$$$$$$$$$$$$$$$$$$$$$
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RE: miles per gallon - 4/19/2008 4:01:46 PM
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h2guy8878
Posts: 45
Joined: 1/22/2008
Status: offline
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tell me about the 160 stat, doesnt the truck run hot for emissions? what about inspections?
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RE: miles per gallon - 4/19/2008 6:54:38 PM
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Terminator
Posts: 16
Joined: 2/24/2007
Status: offline
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h2guy8878,
Engine wise it's apples and oranges when you compare your 08 with its prior year. the 08 is a 6.2L 393 HP 10.5:1 compression vs a 6.0L 325 HP 9.4:1 compression engine. The newer engine makes approx 20% more power has larger displacement and runs hotter. Since you have a addional displacement and higher compression you can't expect not to have to pay somewhere, either with higher octane or more fuel, performance costs money. The new 6 speed transmission tries to help a little as the engineers would engineer it to run the engine in a rpm band that whould provide max fuel value (I would assume). Having driven the 08 I can tell you it runs MUCH stronger than its older brothers. Unfortunately running regular fuel in a high compression engine is like shuving your thumb up your ass to keep from farting, it doesn't work well and just plain stinks.
The computers in our GM vehicles include a knock sensor that allows the computer to increase the timing advance just to the maximum point where it does not knock. This provides increased performance. If you run the engine cooler the timing advanced is increased by the computer, gas mileage also increases. Unfortunately the higher the compression the bigger the problem, these engines will knock at a much lower advance setting because they require much higher octane and you have less to work with. My 05 has no problems passing emissions tests or inspections as a result of the lower thermostat. The factory programmed fan temperatures and H2 radiator won't allow the engine to run under approx 185 most of the time, I could make this lower by changing fan (using a aftermarket performance programmer) temperatures points but could begin to create emission issues. This doesn't help you much as you have different situation. I have heard a number of aftermarket tuners are going to be releasing products that will help the 08 allowing you to change transmissions shift points, base timing (depending on the fuel you want to use) and fan temperatures. (search the web for Hypertech, Diablo sport, Jet Performance and Superchips) You can still perform the other items I mentioned and they will help and none of this will affect your warranty. Hope this helps and Good Luck!
Dan
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RE: miles per gallon - 4/20/2008 6:38:15 AM
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jdrew
Posts: 1350
Joined: 11/6/2006
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HWY at 70mpg.. I get about 13.7
In the city I get about 11.5
_____________________________
05 H2 SUT Slate Blue LUX w/NAV
07 Dodge Charger R/T w/Hemi
Hate Cops? Next time you are in trouble, call a crackhead...
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RE: miles per gallon - 4/20/2008 5:35:59 PM
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Terminator
Posts: 16
Joined: 2/24/2007
Status: offline
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Jdrew, nice work! I once read a report that the H2 will obtain it's highest mileage ratings at 65MPH, (thats with no appreciable wind) so you might be able to get a bit more. Nice! My 13.4 is an average about 55% city and 45% highway. It tough to get much more from a rolling brick that weights in excess of 6200lbs. PS my neighbor's Excersion gets 6 mpg, uphill, downhill, falling out of an airplane, it just doesn't make a difference, that's it!
Regards,
Dan
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RE: miles per gallon - 4/20/2008 6:05:11 PM
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Hummergirl4
Posts: 1019
Joined: 4/24/2007
From: Upstate New York
Status: offline
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quote:
ORIGINAL: TigerLily
I average 11.8.
11.9 here
_____________________________
Silly boys... trucks are for girls
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RE: miles per gallon - 4/20/2008 7:11:15 PM
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Terminator
Posts: 16
Joined: 2/24/2007
Status: offline
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Hummergirl4, What is your ratio (% highway and % city) also what do you cruise at (MPH). Perhaps we can come up with a general stock vs modified gas mileage standard.
I am working on is shortening the step bars on the H2-SUT, I think moving them closer to the body will provide an additional mpg increase as well as giving additional ground clearance and better foot placement for getting into the cab. Gonna give them a chop job this week!
Regards,
Dan
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