Downsize HP's

I performed the same tests as KD5 but using a Mack Ch600 series with the Mack E427 & super ten.

Luv'd that truck even though it took 40 acres to turn it.

Pulling food grade tankers all 48 & Can.
Always somewhere around 79,900 or empty.

Company gutted these trucks back to a 350 (or less maybe) & 67mph.

At their settings best I could do was 5mpg give or take a decimal point.

I "snuck around" the computer on mine which gave me a triple digit truck.
It also gave me back the power.

After all was said & done, I was consistantly seeing 6-6.5 even out west where I typically ran.

The company remained unconvinced because the salesmen & the garage chief didn't want to look like idiots for recommending the guttings.

 

I'm always looking to improve the fuel milage also, my truck has a 400hp cummins and an eaton 10speed, 355rears. I travel at around 60 to 62 mph, ( Swift drivers pass me, makes them happy) I am usually between 75k and 79k when I leave and am seening consistant numbers of better than 7mpg, usually around 7.2 or 7.3.. until I get up into New England, then it drops to around 6.5. Still not shabby in my eyes.

I took a load of paper products (72k) tues from Saratoga Springs NY to Jersey City NJ and was seeing around 8.3.

I short shift the low side at around 1100, 1200rpm and the high side at 1300, 1400rpm, I also keep a very large distance between me and the people in front of me. This alows me to slow with my jake brake and not mash the foot break, I run my cruise as much as possible too,

My best I've seen yet was 9.0, hauling an empty reefer back to the yard from home. ( Central NH to Front Royal, VA) although it took me about my whole 11hrs to do the run. (Usually I do it in 10hrs). Empty my truck and reefer weigh 40k.

My parents have a 33ft fifth wheel camper they haul with a 96 dodge dually with a Cummins and auto transmission. The best he can get is around 10 or 10.5 mpg.

I could probably do much better if I raised my hp up a bit, but for now I'll keep them where they are.

 

My dad gets about 7.3 MPG with his 99 Western Star with a 550 cat 3406e and 13 speed easton. He gets around 13mpg bobtail and 10-10.5 pulling empty reefer.

I put 2000 miles on my truck this week and have averages around 6.75-7 mpg with idleing

 

As an aside to the mpg comparisons; You need to take into consideration where your fuel came from.

More importantly, how warm was the fuel you put on.

As many already are aware, there's been great debate & legal activity in Congress & courtrooms over "hot fuels" being sold throughout the states.

I believe you can attribute some of those decimal points of worse mpg to the temperature of the fuel being too warm.

I thought of this when you presented a worse mpg in New England. I recall that much of the fuel there is brought in by ship thru New Haven Terminal, pumped into tanks & distributed by underground pump lines throughout New England. Naturally there's local fueling for gas stations coming out of their as well.

I am pretty sure that the fuel in the super tankers is still pretty warm from the manufacturing process. It doesn't get a chance to cool very much, if at all, while in the tank farms. Plus, when you JetLine the fuel underground it gets warmer from the compression process taking place in those lines. Together, I think the fuel is well above the 60' temp that it is characterized & sold at.

I recently read how much less "bang for the buck" you get from warmer fuels & although I don't have that spec in hand, I do recall it was several tenths worth of mpg per tankful.

Just something extra to consider when you make your mpg tests & comparisons.
rtc

 

I am unsure of this "hot fuel" debate. I have noticed for years though, that outside air temps play a big part in fuel economy. In my personal vehicles, and my big trucks I seem to get my best economy when it is in the upper 60's usually between 68 and 72 degrees outside. Also my economy is much higher at night than during the day. This probably has something to do with air density, humidity, barometric pressures......

My mpg drops when I head for New England because of the routes I drive. Usually I take I81 north to Scranton PA, then across I84. Lots of hills to climb and I usually have to drop 2 or 3 gears to pull them.

I tried this week going across I78 to New Jersey, and north on I287 and I684 to I84 and noticed that I got 6.1mpg. Usually it's 5.8 or 5.9 by going the other way I listed.