I know lots of folks have psoted about keeping the rpms under 2000 for best mpg.
I must live to close to Missouri

I drove 500+ miles today.

1st half was at my normal driving : cruise set at 72.5 ish
Overhead said 18.1
EGT flat &level about 700
Boost 7.5-8
RPMS 2000-2100

2nd half on the way back on same road : cruise set at 67 ish (man it seems soooo slow)
Overhead said 21.3
EGT same Flat&level about 580-600
Boost 4.5-5
RPMS 1800 ish

Noticed EGT about 100-125 degree cooler
And boost about 3 lbs less.

In case your wondering how I got that close on mph, I have a etrex vista in the fornt window.

GuessI should have listened.

I will be driving slow now that diesel in Iowa is 2.20.
It probably won't be 67, that is just too slow
Figured I would push on the way to customer site and then backoff on the way home.

Just goes to show how darn smart folks here are.

 

I am one of those guys that usually takes it easy and drives the speed limit on trips. Whether its for safety, fuel mileage, or I just hate getting tickets I don't think its worth pushing it.

If you think about it on a 500 mile trip you only lose around 30 minutes between those two speeds you drove, but saved about $9 in diesel. Heck I spend more time then that on the jon reading fishing magazines!

 

I used to be a reserve deputy and I learned that 7 mph over 90% of the time they will not stop you.

That's 90% not 100.

I have drove 72 for 1.5 years now and never been stopped.

 

a good friend of mine is a state trooper and the general rule of thumb around here is 11 MPH over and you will get stopped. anything below that and they "usually" don't mess with you. note i said usually. you have to be ****ing up pretty bad to get stopped under 11 MPH.

oh yeah... if i can keep it around 60-65 MPH i can get 18-19 MPG on the freeway.

britt

 

the hell with saving the 9 bucks I want my 30 min.If i wanted to go slow I would have got a power joke

 

I always try to see if I can get better mpg when I start out Cruise Control set 70mph(with the 315s thats about 1800rpm). But in Texas the darn slow lane runs 75mph and I still cant stand everyone passing me and giving me that old and slow smirk. So I will probably not know if I could get better mpg until I really do get old and slow .

 

I agree with T-7 on getting pulled over if faster than 10mph over limint. I also agree with RamwheelsBy4 about bigger tires so that you can do 80 and still get good fuel economy (85 if the limit is 75). I don't need to race to 60mph, but I'll race over 2000 miles. I use the truck to pull things I like to race (sleds, boat, ATC 250r).

I like being able to follow that guy/girl doing 90 about 1/4 mile back so they get the ticket and I get to go fast too. With stock gearing, that's just not feasible.

I did recently run a stock truck at 3000rpm for about 25-30miles (doing the above technique). I reset the overhead after about 2 miles. When I slowed for my exit the overhead read 10.5avg. I thought that was pretty good for running past the rated speed.

 

In Alabama you are safe at 5 over.

 

I try to keep it under 5k rpm so I can keep it over 7mpg. I tried to run 60mph to save fuel this time out but after 800~miles I couldn't stand it anymore. Had to bump it up to 65-68mph. Tried it with the Cummins too. 60 feels sooooo slow on the big interstate.

 

ok, this is going to really suck for me... my little fronty gets better to about 80 (drove to houston from middle Oklahoma). 65 to 70 down (20 mpg) 80 to 85 back, (22 mpg)

 

Take this with a grain of salt...The 1/2 hour/$9 reference only works if your driving recreationally. I drive to do my job, and that 1/2 hour would cost me a whole lot more than $9. So if you are trying to save a few dollars on fuel, MOVE OVER, I'm coming by!

JNCK,

I drove from Sioux Falls SD through Mason City, Iowa Falls and into Cedar Falls through that crazy storm today. I saw 4 semis on their sides from the 70mph wind gusts (wind direction changed from north to south twice today at 30+mph's while I was driving) and there were tornado warnings along Highway 20 while I was on it...That may have been one of the most nerve racking runs I have ever made. I was always slightly ahead of the worst of it, but I had to deal with those front winds. FYI I still got over 18mpg's when I filled up after 517 miles on the odometer doing 72-75mph.

 

I know what you mean about the wind today.
My pyro cruised at 800 instead of 500 trying to busk the wind.

I think I have it figured out.
Buy a Xzillaraider. You should get about 2-3 mpg improvement so I can drive
72 again without sacrificing fuel mileage.

With diesel at 2.20 it will pay for itself in about 5 months with my driving

 

Wind is almost always blowing from the south here. Trips going north always get a few mpg better than heading south unless you are being pushed by a norther. I don't think people realize just how much difference wind makes. Recent trip from Houston to San Antonio, cruise set on 70, fresh fill, 18.2mpg (about a 20 mph wind from the sw, I was going west). Return, same speed, tank topped off I was showing 21.1mpg when I pulled into my drive. Exact same drive/speed but the front had blown out and it was basically calm and maybe 10 deg. cooler.

There is also a slight elevation change but shouldn't be enough to matter...

 

The best mileage is obtained by no wind not a tail wind. And the elevation does make a difference. I used to get 1 mpg less on the old detroits going to Chyanne than coming back from Alabama. About a 5000 foot gain and all flatland.