need some imput fellas
 

I need some help here
I am trying to get more mpg and I am getting from 5.1 to 5.45 now.
here is my info
2005 kw t 800
c-15 475 hp
10 speed
I keep a clean air filter and try to stretch my fuel.
my truck tops off at 70 mph.


any suggestions?

tks

What size tires do you have and what is your rear axle ratio ? Do you have a full sleeper with a roof fairing or a flat top with nothing ? If your truck tops out at 70 is that how fast you run or do cruise at a slower speed ?

The driver probably has more to do with your mpg than any other signal factor. One thing you could do is slow down and try to plan your stops. Drive like you have an egg under your accelerator pedal. Speeding up and slowing down can eat up your fuel. If you pull a van and own the trailer you could install a bubble on the front of the trailer. There are also wind deflectors that are also supposed to help with wind resistance.

Your definetly right Gman. I wonder other things too though. If a driver has 3.90 or 4.11 gears and 22.5 tires and they're running down the road at 70 mph then their mileage is probably not going to be good because of the high RPMs. He probably has a more normal setup but I just wanted to find out. You do see a lot of drivers burning through the gears with their foot to the floor just to race to the next red light.:cool:

I see that a lot, TK. Some of these drivers like to wind through the gears even though they know they will need to stop at the next light. As to the above poster, if he has low gearing that could have an impact on his mpg. Where he runs and what he hauls will also have an impact on fuel economy. It would be good to have more information.

Having a BIG Cat engine is your biggest problem. A big fuel waster. Air filter has nothing to do with it. A dirty air filter gives you the same MPG as a dirty one, since engine is computer controlled/compensated. The only thing that happens with a dirty filter, is you start losing power.

Try progressive shifting through the gears; 1st shift @ 1150 RPM, then 1200, then 1250, then 1300, etc. It will save fuel.

I have heard air tabs help with fuel mileage. I have a intl coe that has always gave me real good m.p.g. mine tops out at 70-72 m.p.h. at 1850 rpm's it still gets 6 min m.p.g. if I drop to 62-65 m.p.h. I will get 6.5-7.2 m.p.g. min. I have never known why at 1850 rpm's mine gets the good m.p.g that it does. it just does.

I get fairly good fuel economy with CAT engines. The gearing and how you drive has much more to do with it than the engine you have under the hood. I have always found that a dirty air filter will not only affect power but fuel consumption. When demands are made on an engine and it cannot breathe or get enough air then it will compensate by using more fuel.

Nothing wrong with a "big Cat engine". Mine is tuned up to 550 HP 2000 lb-ft torque at 1425 RPM and I get 6.5 MPG (US) with heavy loads and 7.3 with light loads all day long. But I cruise at 62 MPH 99% of the time and thanks to 3.42 ratio the CAT spins at 1,325 RPM only. Having an aero truck helps too: 2004 International 9400 will push less air than the T-800.

you probably have a slight leak in the air-to-air turbo system and at high rpm the leak has less effect on the engine performance due to high pressure inside the hoses. rutherford mentioned this once on his radio show.

here are the specs
2005 Kenworth
Model T800
Sleeper Size 72"
Sleeper Aerocab Aerodyne Sleeper
Engine Specs Caterpillar
Engine Type C15
Horsepower 475
Transmission 10 Spd
Suspension AG 400
Ratio 3.36
Tires 22.5
Wheelbase 230"

I have noticed a air leak between the turbos.
I usually drive around 70 on the interstaes,but lately I have dropped down to 60-65 and mpg improved to about 5.45 from 5.1
I am going to try the progressive shifting and see if i can get the air leak fixed.

I tried to edit my post,but took too long and I had to rep[ost
thanks for the input so far


here are the specs
2005 Ken worth
Model T800
Sleeper Size 72"
Sleeper Aerocab Aerodyne Sleeper
Engine Specs Caterpillar
Engine Type C15
Horsepower 475
Transmission 10 Spd
Suspension AG 400
Ratio 3.36
Tires 22.5
Wheelbase 230"

I have noticed a air leak between the turbos.
I usually drive around 70 on the interstates,but lately I have dropped down to 60-65 and mpg improved to about 5.45 from 5.1
I am going to try the progressive shifting and see if i can get the air leak fixed.I used to run my cruise control at 70 mph down I-95 a lot.

2005 KENWORTH T800 Conventional Truck w/ Sleeper For Sale At TruckPaper.com

that is a link to a truck almost identical to mine.

I usually run from NC to Ga,Fla,Southern Pa and Ohio,and all points in between.
Most of my loads run between 40,000-45,000
and every now and then I haul 3000 -8000 loads when I can get the loads.

It sounds like you have one of the new engines. Some of those have had some problems, especially with fuel mileage. The air leak might be causing you some problems. I would check my driving to see that you can plan stops and starts and not get into a big hurry when doing either. One thing you might do is find a dealer who can check your ECM. There could be something that is not working properly that is causing the problem. It is usually not expensive for someone to check the ECM.

What do you know about it? Please, tell....

Tommy, CAT is VERY specific engine, and assuming there is nothing wrong mechanically, the way you drive it, makes all the difference. It's not just a speed, it's also how you get to it. Be very gentle, try to keep your RPM at around 1300, and not over 1500 ever, unless you are going down the hill. Let him do the job, don't push it, unless you absolutely have to...you might be surprised. Your specs is about perfect, so check all the other stuff, and you'll do fine!

Usually, this is a symptom of a leaking Charge Air Cooler. The higher speeds are compensating for the leak, when you slow down you loose pressure and your fuel mileage starts to drop.

I'm sorry to say, but with a 05 C-15 ACERT, thats about the best your gonna do man. I did everything I could to my 05, and I still was stuck around 5.5-6.2mpg

Wrongway Tommy,

I drove the same truck with Tmc although it was 13 speed, same Cat engine with 3:36 rears and I averaged about 6.2 mpg. I didnt always progressive shift like I should have and I was pretty much at the limit (75-80k) most of the time. I'm sure I could have gotten much better if I cut my idle time down too. just my .02

a update fellas!
I have tryed to do a few things different
like some progressive shifting and also slowed down
I would set the cruise control at 1200 rpm`s [ 58 mph ] and just sit back and cruise
and it was kinda hard slowing down and being the slowest truck on the road
this week I`ll set it on maybe 1300 rpm`s and see how that works

my mpg increased a lot so far
here are some figures I got and figured them when I filled up- a lot better than 5.1-5.3
6.43
5.33
6.523
6.23
5.65
6.67
6.523
5.29
5.88
I looked for light loads and sometimes I got heavy loads but the worst
mileages was with heavy loads up some long runs thru the hills

I am going to have a mechanic look at my truck soon as I am go9ing on a short vacation with my wife later this week

thanks guys for the imput!

Tommy aka skidrow