10 MPG at last!!
Posted 05.24.2009 at 12.57 AM by Frenzy
On May 22, I finally did a 10 mpg round trip run from Yreka CA to Sumner WA. This is about a 990 mile drive. My loads are light, about 12K, and most of my driving is done in Oregon where the speed limit is 55.
Three years ago my C 15 sucked a valve. I had it rebuilt and rerated to 500 hp. At the time of the rebuild the shop found two bad injectors and a cracked turbo housing.
Before the rebuild I had a hard time pulling 7.5 mpg from the truck. I had a difference between my ECM and pump gallons used of about 12%, with the ECM showing more fuel used than what I was putting in.
After the rebuild the mpg's jumped into the 8's, and after one run of 9.5 I set a goal of getting 10.
The only thing I had done before this was putting Centramatic wheel balancers on the steers and the drives. Mileage improved by about .25 mpg.
In late summer of 07 I changed over to super wide singles. I had a problem with the old steel rims rusting to the point where I had to replace one because it wouldn't hold air any longer. The super singles saved about 400lbs but there was no increase in the mpg.
The change over to ULSD knocked the mpg by about 10%, followed shortly by the fall change to winter grade fuel, followed shortly thereafter by the annual Sept-May rain festival. The ULSD problem is (IMHO) primarily a lubrication issue, and secondarily a lower certane rating. I ran a 7% bio-diesel mix when I could, or a Power Service additive when I couldn't. This took care of some of the mpg loss.
In the spring of 08 I added AirTabs to the tractor and saw an immediate increase of about 4%. I started to consistantly run in the upper 9's, but never getting to 10 on a round trip. 2008 may have been a terrible year for the trucking industry, but it was a highly profitable one for me.
With the Fall weather came the fall of the good times. Loads started to be cancelled, the fuel surcharge dropped and the winter fuel and the winter weather dropped my mpg down to the upper 7's, worse than what had happened the year before. The engine was getting to be close to 200k from the rebuild and I was thinking that the bloom was coming off of the rose.
I MotorSilk'd the engine, transmission and fuel tanks. After a month I had started getting the mpgs, when the weather was good, that I had gotten last summer.
I had started to do more Sumner to Spokane loads. This gave me an opportunity to experiment with how to go up a long grade. There is a 10 mile, roughly 4%, grade between Vantage WA and the rest area at Ryegrass. While I could pull that grade doing 60 in 10th gear, I found that running it in 9th at 1100 rpm gave me the best mpg.
On this 10mpg run I maintained 55 mph drive speed, ran the longer grades at 40 in 9th, and used the MotorSilk fuel treatment. The highest mpg I got on the way down was 11.4, beating an old record of 10.8.
Ken
Three years ago my C 15 sucked a valve. I had it rebuilt and rerated to 500 hp. At the time of the rebuild the shop found two bad injectors and a cracked turbo housing.
Before the rebuild I had a hard time pulling 7.5 mpg from the truck. I had a difference between my ECM and pump gallons used of about 12%, with the ECM showing more fuel used than what I was putting in.
After the rebuild the mpg's jumped into the 8's, and after one run of 9.5 I set a goal of getting 10.
The only thing I had done before this was putting Centramatic wheel balancers on the steers and the drives. Mileage improved by about .25 mpg.
In late summer of 07 I changed over to super wide singles. I had a problem with the old steel rims rusting to the point where I had to replace one because it wouldn't hold air any longer. The super singles saved about 400lbs but there was no increase in the mpg.
The change over to ULSD knocked the mpg by about 10%, followed shortly by the fall change to winter grade fuel, followed shortly thereafter by the annual Sept-May rain festival. The ULSD problem is (IMHO) primarily a lubrication issue, and secondarily a lower certane rating. I ran a 7% bio-diesel mix when I could, or a Power Service additive when I couldn't. This took care of some of the mpg loss.
In the spring of 08 I added AirTabs to the tractor and saw an immediate increase of about 4%. I started to consistantly run in the upper 9's, but never getting to 10 on a round trip. 2008 may have been a terrible year for the trucking industry, but it was a highly profitable one for me.
With the Fall weather came the fall of the good times. Loads started to be cancelled, the fuel surcharge dropped and the winter fuel and the winter weather dropped my mpg down to the upper 7's, worse than what had happened the year before. The engine was getting to be close to 200k from the rebuild and I was thinking that the bloom was coming off of the rose.
I MotorSilk'd the engine, transmission and fuel tanks. After a month I had started getting the mpgs, when the weather was good, that I had gotten last summer.
I had started to do more Sumner to Spokane loads. This gave me an opportunity to experiment with how to go up a long grade. There is a 10 mile, roughly 4%, grade between Vantage WA and the rest area at Ryegrass. While I could pull that grade doing 60 in 10th gear, I found that running it in 9th at 1100 rpm gave me the best mpg.
On this 10mpg run I maintained 55 mph drive speed, ran the longer grades at 40 in 9th, and used the MotorSilk fuel treatment. The highest mpg I got on the way down was 11.4, beating an old record of 10.8.
Ken
Total Comments 7
Comments
 | Not to sound too stupid,what are air tabs?Thanks,JW |
Posted 05.24.2009 at 12.21 PM by jwseve2002  |
| | JW, Air Tabs are vortex generators that help to shape the flow of air around vehicle, thereby reducing drag. Their website has a much better explaination of how it works than I can give. Google air tabs to get to the site, or Google vortex generators to find out how they are used on aircraft (much more theory). I spray painted mine green to match the color of the tractor. The tabs blend in ok. If I had to do it again I would have ordered the black tabs instead of the white as I think the paint would have been a little closer. Applying them on the side went quick, about 20 mins per side. Top of the sleeper went slower because there is a curve line that you have follow in order to get the tabs to be flat. Spent about 30 mins doing that. A tractor kit of 80 air tabs cost me 200$ when I did it. Ken |
Posted 05.24.2009 at 10.24 PM by Frenzy  |
| |  Heard about the air tabs. Looked at the site, and all their pictures look as if the truck has a zipper on it. LOL Did you apply them to the trailer as well? I just wish that they were a bit more attractive. But 10 mpg, holy cow!!! Thats some serious savings! |
| Posted 05.27.2009 at 08.41 AM by bullhaulerswife |
| | I did sneek 2/3 rds of a set on a company trailer. I did the sides only. I mounted them on the frame for the liftgate, and spray painted the tabs and the frame black. You couldn't see the tabs unless you were right next to them or looking down the side of the trailer. The roof was fiberglass and very dirty and molded. I was worried that the tabs wouldn't stick, so I left it alone. I didn't get any mpg gains at all from doing the sides. I thought what they really needed to make was a supertrucker special chrome set with led lights at every corner.  I've been meaning to ask you from where or what program did you get your avatar from? I admire the expression. ken |
| Posted 05.27.2009 at 11.55 AM by Frenzy |
| |  i didnt know a thing about airtabs untill reading ur blog thx for the info and most ive seen is 9mpg in my international prostar premium congrads. |
| Posted 05.29.2009 at 12.21 PM by milemover |
| | That's really impressive! |
| Posted 06.03.2009 at 03.55 PM by PTCChallenge |
| | Its a meez, you can google the site. Create an account, and if you have a photobucket account, you can link them together and save directly to photobucket. |
| Posted 06.10.2009 at 09.19 AM by bullhaulerswife |
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