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mpg's on 12 valve

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Old 07-05-2011, 03:08 PM
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Originally Posted by dieseldel
When new, I got 21mpg consistently, now I get 17-18 consistently.
Never been able to find out what caused the drop. I just changed suddenly.
Maybe the fuel now is crap.
My speed averages 77mph typically.
In town, same mileage. Never see a difference.
A load of up to 2000 lbs doesn't seem to affect mileage at all. Pulling my 9500 lb trailer does, drops down to 10mpg. I drive about 65 with the trailer, at 73mph drops to 9mpg.
the fuel we are using now has less btu's than in '95
Old 07-05-2011, 03:18 PM
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Originally Posted by Dojman
This is just like every thread about mpg's. Very wide spread numbers. I think some are figuring with hard numbers, some are using the overhead. My 96 model is pretty consistent at 19.5 in mostly rural highway driving, 60-63 mph @~1800 rpm. Seen 20 one time. I run 285's on it, and my numbers are not compensating for that. Just straight off the fuel pump and odometer. My daughter said she got 24 in hers once running around 70 mph. My old truck drops pretty quick when I start getting that fast.
I also think its due to speedo accuracy
Old 07-05-2011, 06:36 PM
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well i get 27 if I stay around 55 mph .I get 24 at 65 mph and 19 mixed town here. I don`t convert to the US gallon I use 4.5 lt per kl and 1.56 for the miles. It really don`t matter
much because the truck IS not for Sale! LOL
Old 07-05-2011, 07:39 PM
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CSA,
That full emty full emty crap is the shaft on the sending unit. just fixed mine after it drove me crazy for a year. Dealer wanted a gold bar for a new unit and I get wholesale price. Just pushed the pin out that the unit rides on and put a small washer on it and braded it down to hold the sender on tighter. had to sand a bit off the plastic shaft to allow for washer. easy fix after getting the unit out of the tank. Lifted my bed to access it. As for Mileage your elevation may have something to do with it. I have a '98 5 spd that gets a consistent 19-21 unloaded hiway. 17 city. i have a '02 auto that gets 19 -20 hiway and 17 city. the 5 spd gets 14.5 average towing 6k and the auto gets 13.5 average same load. But I tow with a gear vendors overdrive and never tow in 5th or overdrive with auto. i use the gear vendor for overdrive on both trucks. Makes a bunch of difference if you are barely in a too tall gear! Taller tires than stock kills mileage when loaded also.
Old 07-07-2011, 09:49 PM
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I am getting 22-24 mpg on the interstate driving and 20 in my little town. 3.5 gears, 4x4 and a 5 speed. I log every tank in the book I keep for fuel. Putting on 1000 miles a week and runs like a champ. Speed is at 60-65. I also add 16 oz of ashless 2 stroke oil in every tank.
Old 07-10-2011, 07:33 PM
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ok one last thought...you guys getting better mpgs do you know your hp...just had my emission done in march put down a lazy 178hp rwh..im thinking better mpg=higher hp? cuz i gota keep the pedal down longer to move trailer...yes..no..
Old 07-11-2011, 12:06 PM
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Originally Posted by csa
ok one last thought...you guys getting better mpgs do you know your hp...just had my emission done in march put down a lazy 178hp rwh..im thinking better mpg=higher hp? cuz i gota keep the pedal down longer to move trailer...yes..no..
had mine truck on the dyno last summer and I think it was about 345 hp. I would like to have it checked again now that I have the 3000 rpm governor spring installed . Had the truck and fiver out camping this weekend and it seems to pull much better now with the spring installed. I do want someone to set the timing and valves and move the #10 plate ahead from the stock setting. Hope to get this truck set up this summer. later Don T
Old 07-11-2011, 09:07 PM
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Originally Posted by csa
ok one last thought...you guys getting better mpgs do you know your hp...just had my emission done in march put down a lazy 178hp rwh..im thinking better mpg=higher hp? cuz i gota keep the pedal down longer to move trailer...yes..no..
I have heard of different trucks with higher HP getting as good of mileage as my stock ve powered truck. IMO, it doesnt have anything to do with the HP.
Old 07-11-2011, 09:50 PM
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I've got a 92 W250 w/4sp auto, 4.10, 34" tires, 4wd. initially, i got 16 both city and hwy. I installed a gear vendors unit and drove this past weekend only on hwy for the mpg test and got 12.7mpg over 185mi and 13.3mpg over 203mi.. i'm mystified! used a speedo app for milage since it runs about 5mph fast....also, flat terrain, 65 to 70 mph in douuble overdrive. not sure what rpm but it definetly droped in the GV overdrive
Old 07-12-2011, 04:16 PM
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...as follow-up, the GV rep indicated i was running at 1400rpm(at 65mph) to 1630 rpm (at 75mph). since i was holding 70 mph max i must have been at max rpm ~1500rpm. if running this low of an rpm is negative for fuel economy i guess i'll have to speed up! any comments welcome...
Old 07-12-2011, 07:17 PM
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I find 2000 rpm is the seat spot for my truck. i seem to get the best fuel usage at that rpm. works for me. later Don T

Last edited by Don T; 07-12-2011 at 07:25 PM. Reason: dang can`t spell
Old 07-12-2011, 07:57 PM
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TEC, I have used the Gear Vendors on all my trucks for years. You have to keep your RPM's at above 1650 to reap the rewards. I like to keep mine at 1800 -2100 for peak mileage. The problem when in double over is that you are too low rpms unless you are running 85mph! They are really made to give you extra gearing between 3rd and 4th and between 4th and 5th. Best application is using it to run with the trans in 1 to 1 with the over drive or 5th gear locked out. It is in it's peak there. It saves the 5th gear nut or the overdrive on an auto.
Old 07-12-2011, 09:37 PM
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Don T- thanks for the input.

Whiskers - that sure makes sense now that I've driven with the gear vendor unit. I'm not sure I'll ever need the double overdrive unless I want to contribute to the state's revenue stream! that said, i was considering a gear change to 4.56 to take advantage of the double overdrive (ie get rpm~2000 in OD) until you mentioned the 5th gear nut issue...i wasn't aware of this. i need to figure out the rpm in 3rd over with current setup. i may just keep it simple and leave it alone!
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