fuel mleage

I would prefer 3.55. When I do some major work on the rears and change some things, will probably do that change as well. Not straining the engine now though. Engine runs very comfortable at 1350-1400. Good response and is not lugging. Now, I do drop a gear and raise the rpms if under a hard pull on hills, mostly because EGT's go up too quickly at the lower RPMs under a hard pull. With the 13 spd, I have a little room to modify how I do things based on conditions. But for regular highway running on flat or gently rolling hills, 1350-1400 works pretty good on this engine. I have tried various rpm/speed combinations and this is where things have settled in. On totally flat ground, regardless of weight, even 1300 (59-60 mph) is not straining this engine and I have ran that way a number of times, especially in places like Hwy 30 thru Indiana and Ohio. And the fuel mileage speaks for itself in those situations. Have busted 8 a lot of times on those roads. And if there was any strain on the engine how I am running it, it would show up in things like oil samples, which all look as good as similar engines with half the life on them.

I am not sure what year or engine you had in that log truck. That would make a difference as well. Different models and years of engines are different in how they like to work. There is no way my '06 ISX is going to get anywhere near the fuel mileage I get now if I ran it all day above 1500 and higher than 65. And the rolling resistance of low pro 22.5 rubber is far lower than 24.5 rubber, and that equates to better fuel mileage. Right now, the ECM shows that the top speed is set at 85, but I have never had it that high to find out. Never had a reason to prove it.

Regarding the rear end gear change, that will only be a part of the story. Am dropping the front drive axle for a 20,000lb pusher/lift axle and replacing the rear diff with a 25,000lb drive axle with lockers for slip traction. This will reduce maintenance costs and improve fuel mileage. Under a light load or deadhead, just lift the pusher axle and run on one drive axle. Even with pusher down, there would be less effort since I would not have to be turning a bunch of gears in a drive axle that wasn't being used as a drive axle. I will probably put on something smaller like 19" wheels on the pusher to enable lift without causing a problem. Have discussed this change over with a local place and total cost would come in at around $6000 with brand new pusher and rebuilt drive axle and new drive shafts. Getting some trade in allowance for old parts. Added plus is that I will save around 500lb in weight by making the change.

 

You sound like a smart man to me, this is what I have in mind for my next dump truck, currently I'm running a try axle, which is actually four axles, my next truck, I'll make it a single axle with a pusher since I dead head half my trips there is going to be a considerable savings in fuel and tire wear, plus I'm going to be able to get almost the same tonnage with a lot lighter truck, not to mention the saving in tolls, and the list keeps going on and on, now traction is not a problem for me since I'm always on pavement, and the last time we had ice down this way was so long a go that I can't remember, well actually I don't think there was truck around here back then.

 

Hello guys, I have a 2004 9400i International with cummins isx 435 engine. The truck is averaging 5.7 mpg on flat roads and with loads under 25000 lbs. I want to know how can I get better mpg? Should i disconnect EGR plug? Is there any side affects if i disconnect the egr? Or is there a better way to improve the mpg? Thank you

 

How long have you been driving? Under a year?

I'm thinking you can probably squeeze a 20 to 30% increase by working on your technique.

 

One thing about going to 11R22.5 is that they have a higher rolling resistance than a low pro 22.5. Kinda going in the wrong direction to get better mpg.

Everything else you state is spot on. Regarding fuel filter, I use a davco so I can see when it needs changed. I regularly get between 40,000 and 60,000 miles on fuel filters.

 

Hi I have a good question,what time is better for the mpg wintertime or sommertime,I think the coldtime is worst for mpg is this correct

 

Wintertime is worse for a number of reasons. Winter fuel blends have a lower Cetane rating, meaning there is less energy in the fuel because it has more No. 1 diesel in it - keeps it from gelling. Cold air is more dense, so it takes more energy to push your truck down the road. Tire pressure decreases with temperature - and lets face it - we're all less motivated to get out on a cold morning and pump-up the tires; underinflated tires get worse mileage. Diesel engines are more efficient when they run hot - that's not the case in the winter either.

There's more of course...