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Pickups Diesels Chevy Silverado and GMC Sierra Duramax Fuel Mileage
506 messages, Last post on Nov 30, 2009 at 5:21 PM
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I just towed our fifth wheel with the 2500HD Duramax/Allison/4 x 4 truck. Overall average was about 10 mpg, mostly flat highway towing. Regarding the Allison, I find it rather strange that it stays in 4th gear up to 65mph, the rpm level finally forces the shift around 3000rpm. This is in tow/haul mode. I did notice a drop off in uphill speed, it dropped of more than I thought. It reminded me of my 2500 Ram with a Cummins. Does this seem normal or are there some issues? The truck is a 2002 model with 45k on it. P.S Typical mileage empty is about 17mpg. |
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Replying to: opmech (Jul 11, 2005 8:58 pm) I have had my 05 2500hd crew cab std bed 4x4 Duramax for 11 days now, and have switched out the pizza cutter 245/75/16's with BF Goodrich AT TA KO 285/75/16 which added about 2.5 inches. Also I added a leveling kit that lifted the front end up 2.5 inches, so that the top of the front wheel well matched the height of the rear. Overall the front has come up 5 inches, and the rear 2.5. It looks great! I did have to trim a very small amount of the front valence to keep tires from rubbing. Now that I have done that I am very happy. I have a friend with the exact same truck who put 295's on w/o the leveling kit, and he said his rub. Now that I have trimmed the front, I wished I had gone with the 305 or 315's because they are a little taller, and almost a full inch wider. FYI, the leveling kit was $275 installed. I would like to hear some comments on some of these "programmers" or "chips" for the new 6.6 Duramax LLY (LLY = 8th digit in Vin is a "2"). I am not towing/hauling anything (except my own ass) and wondered if is worth the $400-$900? I am mainly concerened with increasing my fuel economy, but wouldn't be bothered with a little faster "off the line" reaction. I am concerened that I would need to worry about Exhaust Gas Temperatures, switching out exhaust systems to a wider diameter, installing a cold air intake system, digital in the cab monitors etc. Thanks in advance. Stone G |
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Replying to: maxie05 (Jun 15, 2005 6:18 am) did you change tires to a larger size? If so, did you re-calibrate the tire size in the computer? If you didnt re-calibrate, your truck is registering fewer miles on it that you are actually going, therefore decreasing the number of miles per gallon. |
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Replying to: stoneg (Jul 20, 2005 5:33 pm) Thanks for the info. What kind of leveling kit did you use? That sounds like a great price installed. Also, if you will send me a personal email I will send you contact info for one of my AMSOIL accounts that markets a programmer. I use it in my 2003 and I am happy with the results. I believe he will take care of you on the price as well. Dave |
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Replying to: opmech (Jul 20, 2005 8:37 pm) |
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Replying to: opmech (Jul 20, 2005 8:37 pm) I did see a leveling kit for an 05 2500HD on ebay for something like $40.00 But it took Minco, something like 2.5-3.0 hours to install it, so in my opion it was $275 WELL spent.
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| As of tomorrow I will have had my 05 2500HD Duramax for 2 weeks. Today I had the dealership recalibrate the computer for the 285/75's. The best mileage I have seen was 15.2 MPG on the 5.5 hour drive home from the dealership with the 245/75 doing 82 MPH (give me a break on the speeding thing, Hurricane Dennis was on my 6). I have been getting around 12.5 around town. I am not hauling anything, not even a toolbox (yet), and I am not getting on it (due to the low first gear sucking wind off the line). I am considering a chip or programmer, but am a little nervous about it. With the fuel ecomony and the off the line speed, it sure isnt my old Tacoma V6 anymore! | |
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Replying to: stoneg (Jul 22, 2005 6:18 am) Thanks again, I will look for the kit on ebay. Also, give Roland Trudell a call at 951-272-9090. He owns Rolling Big Power, a Diesel performance aftermarket parts dealer. Tell him that his AMSOIL Dealer, David Daniels referred you to him and that I said he would take care of you. I use the RBP programer and it does have the tire size issue taken care of along with some other goodies. I am very happy with the one he sent me. Dave |
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