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Thread Title:

Shifting for max efficiency


Created On Sunday May 02, 2010 16:56 Diesel Talk
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FredMiller
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Note Sunday May 02, 2010 16:56 View thread in raw text format
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Hi,

I was reading some of the posts concerning fuel mileage and someone mentioned the sweet spot for maximum MPG. I am new to this game and was curious what the most efficient speed/rpm combination would be for my truck. I have an International 9200 with a DD60 11.1. It has a 10 speed Spicer and 3.91 rear. For most shifts I am bringing the rpm up to 1500 then shifting and staying in the next higher gear at 1300 rpm. Is this the most efficient way to shift in an effort to get the best mileage?

Thanks,

Fred
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JohnnyReb
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Note Wednesday May 05, 2010 09:23 View thread in raw text format
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Most recomend progressive shifting. You shift at a lower RPM in lower gears then as you up shift you increase rpm to overcome the loss in torque multiplication you get in the lower gears. If you are standing on it in lower gears you are really wasting fuel, sure the guy beside you is gonna beat you out of the red light but you will pass him while he is getting fuel. Had a guy tell me to act like you have a egg between your foot and the fuel pedal. All trucks will be a little diffrent. A identical truck that came next in line behind yours at the assembly plant will get diffrent fuel mileage. You need to find your sweet spot, it helps to have a instant fuel consumption gauge. Keep your RPM's down as low as possible without lugging the engine to death. Also at highway speed you will find that there is a certain speed where your MPG really takes a nose dive. On a calm day I can run 70mph on flat ground in 15th gear at 1375rpm and get over 7 mpg, bump it up to 75 and I drop over 1mpg. Throw in a head wind and I can easily see it drop to 4.5 mpg. I usually find myself cruising around 70 even though I might be in a 75mph zone. I always use cruise control, thats a real mpg improver. If I come up on someone running slow I'll just mash the pedal to get around then after I clear let up and let the cruise take back over. You will find driving easy will save you more than fuel. I've got 2.2 million miles on my truck. 1st engine was rebuilt at 600K because of a bad liner, still running on the second engine although its getting tired. Original tranny, the 1st clutch lasted me 1.4 million miles. I swapped the rears out last year, started seeing metal on the plug so I just went ahead and swapped them. I've still got a couple original U joints. Also be cool on the stool, in heavy traffic you don't have to be up on everybody. Speeding up and slowing down all the time is wasted fuel. It also lessens the chance of accidents and freight damage from getting into the brakes too hard. Laying back taking it easy will save you all kinds of money. Less fuel, less repairs, less accidents, and less money on blood pressure pills. You won't find yourself screaming through the windshield at someone who isn't listening. We had a meeting about a Month ago at the company I am leased to. Although there were severl O/O's that had a higher gross revenue and more miles I had the highest net last year. So they ran harder for less money. The only thing included in that figure was truck gross and fuel expense because the company doesn't keep up with our maint. expenses. I'm sure with no truck payment that my expenses really widened the gap in net profit. Alright I am rambling, before I get into the benefits of keeping your license clean, BTW I have 0 pts., with the new 2010 regulations I'll quit.
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GoneFishen
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Note Thursday May 06, 2010 16:27 View thread in raw text format
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If you can pull the hill at 1300 do so, if you top the hill shift azt 1650 max. cruise where it feels good and solid. Sweet spot as the factory calls it around 1600 rpm. If we both pull the hill at the same speed and you do it at 1300 and I do it at 1700 I waste fuel.

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DDA tech for 30 years,all 2 cycle,series 60,50 mbe also.
1995 F250, 191k mi.
Lost Wages, Nv
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heavyhaulerss
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Note Thursday May 06, 2010 19:22 View users profile View thread in raw text format
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HEAVYHAULERSS
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heavyhaulerss
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Joined: Mar 2010

Note Thursday May 06, 2010 19:36 View users profile View thread in raw text format
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I have a 11.1 det. with a super 10 the eaton websight will tell you how a particular trans made by them should be shifted. usually 1st gear shift at 1000 rpm's 2nd at 1100 & so on. you really have to get a feel for your truck. i.m.o it is better to rev higher, say at 1700 than to lug it at 1100. it depends on weight, uphill,downhill, some times if I am loaded & up shift from 8th to 9th I may have to rev to 1800 just to grab the lower gear at 1400. if I try to upshift at 1600 I will at times be at 1300 when I hit the next higher gear, witch may not be bad, but... sometimes that 1300 will not pull me out & I will drop to 1200 then I have to grab a lower gear. like I say depends on wind, weight. e.t.c. power of engine & torque. there were times were my truck would pull out from 1300 no matter what. some times it would not no matter what. high rev's waste fuel, low revs lugging is far worse. just get to know your truck. on my ser 60 anything below 1400 feel like I am lugging it. so in higher gears I tend to shift at 1700 & drop in at 1400 min. youtube has great video's on every shift pattern. check one out.

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HEAVYHAULERSS
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FredMiller
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Joined: May 2009

Note Saturday May 08, 2010 01:12 View thread in raw text format
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Gentlemen! Thanks so much for the great advice! I can promise you that I will put all of it to great use. I am one who does not care to spend any more on maintenance or fuel than necessary.

Fred
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