Yet another can of worms...MPG question

I drove a 2004 Columbia with a pre-egr engine for about four years. It was a 450 hp with 10 spd od, and 3.70 rears and 22lp tires. I got better mileage from it at 65-67 than any other speed. I did like the fact that it would lug and power up at 1200 rpm on up as compared to the Detroit. I consistently got 7+ mpg from it compared to my split seat partner that got more than 1 mpg less. Driving habits have a lot to do with MPG.

I must add to the above. The last company I drove for got some of the first '08 DPF Cats that came out. One in paticular gave lots of problems and got terrible mileage. Cat finally put an expermental engine in it that at it's best got 3.8 mpg no matter what speed it was ran at, which was coast to coast, so many miles of constant speed was able to be acheived. We also had some '05 BXS Cats that were all over the place. One in paticular I could get 7+ on any run while others were lucky to break 6. Most were in between. Fuel mileage is a combinatation of driver, and the luck of the draw of how the engine is set up from the factory. If you can reprogram the engine and use a good foot, then that is totally different.

BTW, the company with the '08 Cats that got from 3.4 to 5.0 soon sold all the new trucks before they bankrupted them and bought '07 386 Petes with '06 engines in them. The 08's were 386 Petes also. Huge difference with mileage and realibility. The Internationals with '05 BXS engines were the best in the fleet with more than a million miles on all of them.

 

To the OP and anybody else making mechanical changes with no effect on MPG, here is the best money you can spend on your truck and the best tool to have if you are serious about fuel mileage......




An infrared temperature gun from Harbor Freight for less than $40 (now less than $26 with coupon) is the most used tool on my truck. After running at least 50 miles, I pull over and check hubs and brakes along with tires on trailers since I never pull the same trailer twice makes it a great way to find the slack tire because it will be the hottest.

For those that make changes with no MPG results, more than likely you are like 75% of the trailers I move including brand new ones that have the brakes dragging slightly due to being out of adjustment or have warped brake drums. Just 30 degrees hotter in only 1 brake drum can make as much as a 1/2 mpg that is caused by brakes barely rubbing at one spot on the brake drum. Now multiply this by several wheels with dragging brakes.

FYI. I estimate around 80% of the trucks on the highway have wheel bearings that are out of adjustment that causes fuel mileage loss. Friction is the biggest cause of fuel mileage loss on a truck and the use of a temp gun will help you find them.

I have a quick cheap temporary fix that I will share latter for dragging brakes that I have seen brand new trailers increase as much as 1 full mpg just by taking a minute to do this. Try adjusting the brakes first that takes more time and may still not stop the rubbing to keep brakes within DOT rules of adjustment if the drums are warped.

Harbor Freight link to temp gun: http://www.harborfreight.com/non-co...zIjoiMjUuOTkiLCJwcm9kdWN0X2lk IjoiODkwNSJ9
Note: the coupon for the $25.99 price is available.

 

from reading this post it sounds as most of you are KR clones. your right foot is the best way to control fuel millage. the other things all play a part. find your sweet spot and run it there. that should be good for .5 to 1 mpg.the rest comes with time and learning were to run the motor at. first cheep fix open your exhaust up. there a cheaper muffers with the same flow rate as a P.P. muffer its made by Donaldson I belive the number is 10047 but I could be wrong on that look back in older posts. ecm tuning by mr hainey is by far the best. updated turbo and manifold is costly. tires do them when its time to buy new. cheapest and fastest way is to correct driving habbits. even K.R. will tell you that. I drive 2003 379 320" wheel base 140" custom sleeper 51' rolling tarp step deck 6nz cat somewere around 1000 hp 18 sp 90 day average on fuel 6.4. iam happy with that. set at 600 hp was doing close to 7 mpg.

 

When the fuel bill comes from you're pocket, if you have half a brain.you start thinking,every time you mash the big pedal on the right that's money out of my pocket.don't be afraid to ask a experienced driver,what do you do to save fuel,how is you're truck set up.but not every driver with gray hair has experience anymore,so do you're homework.

 

I prefer the Walker Megaflow muffler that sells for around $125 at most truck part houses and has a 4 year warranty against rust. A straight thru muffler that should give most trucks around 3/10ths better mpg over an OEM stock one and it is galvanized dipped to back up that 4 year warranty.

 

I think you're geared too high for the engine you have, but that's just me.

 

Drop half a gear and run it at 1550 and see what happens. That should be 59 MPH. doesn't cost anything to try it for a week.

For sure you'll gain MPG because of speed and the higher RPM may not affect it in a negative way like people say. It may add MPG.

 

On flat ground the lower the RPMs the better the fuel mileage, but in the mountains or hilly terrain with a load demands higher RPM to pull the hills a lot better.

That is why the larger turbo and better exhaust manifold that Pittsburgh Power sales helps fuel mileage at lower RPMs with almost "0" boost on flat ground and low RPMs (around 1,100).

 

You won't run a 12.7 Detroit at 1100 rpm and get any mileage, or be able to pull itself unless empty with a 50 mph tailwind. They will not run down there stock. Best fuel mileage time and again has been proven to be around 1600. I'm talking totally stock on engines under 500 HP.