Thats all?

[CDyksman]

Well Guys, I just took my first real road trip in the '04.

I am not real impressed with my mileage however.

I took a trip to Lake Powell, pulling and hauling an estimated 7,000 lbs. I had in on cruise when ever possible, set at 70-80 m'sph. I have not hand calculated, but on the 350 mile leg to the lake, overhead averaged me at 10. 5 miles per gallon.

On the same stretch of road coming back, without the boat and about 300 lbs of beer and food, so hauling about 1300 lbs total, I only got 17 miles per. Is this just because of the 315 R70's I put on, or could there be another reason? We did have a decent headwind for an hour or so. Other than that pretty good weather. Temps in mid 70's. Truck turned 7000 miles on return trip



thanks colby

 

[CChase]

17 adjusted for your tire is roughly 18. 5mpg. Also based on my experience and log I keep for mine, my hand calcs range anywhere from 0. 5 to 2 MPG greater than what overhead shows.



Add that to the fact that you're doing 70-80, sounds about comparable to what I see.

 

[klenger]

Your numbers look good to me.

 

[CDyksman]

My old '96 (12v) with 135'000 miles on it Got twelve around town pulling a 13,000 lb front loader and trailer. How much improvement will I see from a n after market exhaust and drop in filter? Or is putting a box on the only one that i will see significant gains?

 

[KBennett]

I have a 1970 18' TT and I am guessing it weighs about 5K dry. Coming back from MT this weekend the overhead said 12. 5 averaging 70-80mph. I normally don't like to go that fast with a trailer but the truck and trailer didn't seem to mind. I can't complain too much because my buddy in his Durango R/T and a 3K trailer was getting 4-5mpg and I was out pulling him on the hills.

Could your 12 valve Cummins pull as hard as a CR Cummins?

Fuel is outrageous right now but production is supposed to be increasing.

 

[JoelCool]

What's the ratio I should calculate using my 33-12. 5 17 tires? Am I correct in assuming my speedometer will be off by the same ratio?

 

[amsoilman]

When the rev's go up... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... the mileage goes down! Keep er down to 65MPH and you'll get better mileage.



Wayne

 

[CDyksman]

??

What is a CR Cummins?

 

[CChase]

Originally posted by JoelCool

What's the ratio I should calculate using my 33-12. 5 17 tires? Am I correct in assuming my speedometer will be off by the same ratio?

It's real rough because tire sizes (metric and standard) are approximations at best of what the tire size is. But yes you can figure a ratio for speedo correction. As it sits with 33" tires, you're speedo is reading roughly 4. 4% lower than you are actually travelling.

 

[robobx]

once you go over 2000 RPMs the mileage goes down drastically.

 

[KBennett]

Re: ??

Originally posted by CDycksman

What is a CR Cummins?

Sorry, Common Rail.

 

[jimnance]

Try going 75 MPH with a gas powered truck and 7,000 lbs in tow. You'd be doing good to get 6-7 MPG. Also, the diesel engine will tow all day and live to tow for many years. You load up a gas engine and tow like that and it won't make 100K.



A diesel engine isn't a magic bullet. What it does best is to reliably run, and run, and run. Along the ways it get's pretty good economy compared to a gas rig. Also, keep in mind that diesels are installed in HD2500 series or bigger. Our trucks weigh a lot.



To me your mileage seems about right, especially considering the 5% upward adjustment for tire size. I took my 315's off because they were hurting my mileage and made the gearing too tall for the load I was hauling.