What RPM do you guys Get the Best MPG's at?

[peashooter]

M35A2/M109A3
I've done some searching for the best speeds to get the best mileages but since so many folks are using different tire setups its a little tough to compare.
I'm assuming that there might be a "Sweet Spot" in RPM's that would give the best miles per gallon so I wanted to see what other folks run at.

so far my 109 is getting about 8mpg with cruising @ 2K rpm (45mph). Tire pressure is 65psi front, 55 rear.
I dont expect much better mileage but I'd be thrilled if I could manage to taste double digit mpg once in a while.

 

[91W350]

My 72 that I foolishly sold would get around 12 regularly at 2000/42 mph. My 68 runs about ten at 2000 and actually acts like it is done pulling at 1800. The 71 was also running about 10 at 2000 and acts like it is just starting to run good. I am sure it is in fuel and timing settings. My 68 has the loudest exhaust note of any deuce I have been around.

 

[hndrsonj]

I would say my M35A2 gets 10 most all the time. I try to keep it at 50 MPH.

 

[big hoss]

I have 395's and when i went to the beach i used 11 gal of gas. The beach is 145 miles away. I got 13 mpg there and back, running no more than 2200 rpm's.

 

[hndrsonj]

I should also say I run 100% diesel. I don't mix any other stuff in it-ever.

 

[JCKnife]

I have never checked the MPG and doubt I ever will. Not sure I see a reason to.

 

[Wildchild467]

the M109 is like driving a block. not aerodynamic at all. try driving it at 40mph and see what happens. sure you could get lock out hubs and a center axle lock out hub too, but the faster you go, the more fuel you burn. also would not hurt to double check and adjust your valves to make sure they are spot on and injection pump timing check. its not that hard to do and at least lets you know that you know what you have in your truck. make sure the airfilter looks good too.

I say its a 109, so its not going to get that great just because its a block. a cheap try is going 40 mph and see what you get then. wont cost anything to try. like i said, it wouldnt hurt to adjust your valves. im crazy with the PM stuff. peace of mind knowing my truck is in good shape without spending much money at all (maybe buy a set of valve cover gaskets).

 

[Carl_in_NH]

Double digits for MPG? Head downhill - a lot. A tailwind helps, too.

That box box on the 109 isn't helping with wind resistance.

 

[Srjeeper]

In this configuration I get between 9 & 10 mpg at 2200 to 2300 rpm's and the trailer is always along.
That translates into 50mph highway on straight diesel.

I've taken the front rear axles out to free up the rears and run 60 psi in the front and 55 in all other tires including the trailer.

 

[swbradley1]

Maybe someone can explain what MPG is and how it would ever relate to an MV.

 

[sandcobra164]

I think I get about 10 MPG's in my M35A2. As posted above, I don't know why it would be relevant, they run good, it blows black smoke out the stack and that's all I'm worried about. For What it's Worth, it can pull 23,000 pounds on a towbar albeit probably used more fuel on that trip. If you're worried about mileage, these trucks do good in the single digits. I just pour more "multi fuel" in it when it needs some. Used oil, stale gas, filtered of course and then some.

 

[Clay James]

I've changed my driving style since I first got it. I shift sooner and run at lower RPMs and get way better mileage. I almost never have it at 2500 unless I'm trying to shift from 3rd to 4th on any kind of hill. I drove to get hay the other day and only drove about 40-45 on the back roads and kept the RPMs 2200 or less and when I got back I checked the tank and the level wasn't much lower. Not sure what the mileage was, but it was pretty good. I'm still running straight diesel so I want to squeeze every MPG I can out of it until I get my WMO processing stuff working, then I won't really care, I'll just keep it lower RPMs to be easier on the engine.

 

[Jeepers69]

I just recovered my first Deuce yesterday. I checked all tires 9:00 - 20s for proper air at 50 psi all around. I was pulling an M105 that came with it, that came as a package deal. The trailer had 6 11:00 -20s with rims in back plus some other odd stuff. I drove 230 miles and used 20 gallons of fuel. Diesel was the only fuel ran in it for quite awhile from what I am told... 50 to 55 at 2300 to 2400 rpm. That is like 11.5 mpg... I was happy to see that. She never missed a beat (except hills) . I am now seeing a small oil leak by left front spring and shock and getting on inside fender. I am investigating that, any ideas to look for I am open for ideas. I cannot pin point it yet. my next step is to power wash it clean and try and locate it.... looks kinda like the bottom of IP. Pics to follow.. I did not get them off camera yet. I will say I love it. and quite the attention getter... Tim

 

[doghead]

Here some data for the LDS, the LDT should be close.

 

[Varyag]

Doesn't some TM recommend 1850 for best mileage?

-edit- haha Doghead delivers

 

[AGE|kshaufl]

Thanks for the chart Doghead. I get about 12-14 not exceeding 2000 RPM. On the smoke, I have none, even on hard acceleration. Is that normal?

That is running 45 gal of diesel and 5 +/- of WMO. I will say the more oil I run the happier she is.

 

[dmetalmiki]

We get 11 MPG. running 50-50 contam (petrol/deisel) and Waste filtered AQTF. more power Smoother running too. I Never exeed 2000 rpm. and go with whatever speed the tire sizes relate to.

 

[Goose2448]

So what I get out of that graph is that you should burn about 11.1 Gals per Hour,Diesel weighs 7.15 pounds per gal, at rated power. Rated power is at 2600 RPMs, which equates to 55-56 MPH, right? So if my math is right, might not be, you should see like 5 MPGs. Everyone says they are getting better than that, so if you get less than 5 mpgs, you know you have a problem.

 

[peashooter]

the M109 is like driving a block. not aerodynamic at all. try driving it at 40mph and see what happens. sure you could get lock out hubs and a center axle lock out hub too, but the faster you go, the more fuel you burn. also would not hurt to double check and adjust your valves to make sure they are spot on and injection pump timing check. its not that hard to do and at least lets you know that you know what you have in your truck. make sure the airfilter looks good too.

I say its a 109, so its not going to get that great just because its a block. a cheap try is going 40 mph and see what you get then. wont cost anything to try. like i said, it wouldnt hurt to adjust your valves. im crazy with the PM stuff. peace of mind knowing my truck is in good shape without spending much money at all (maybe buy a set of valve cover gaskets).

I wish I would have adjusted the valves when I had the radiator out valve covers off and did a flush and new hoses a few weeks back.
Quick Question: is it pretty obvious knowing when the valve is fully open (by turning the motor) before starting the valve lash adjustment?

 

[Redpawn]

Wow I haven't got to put my deuce on the road yet but I figured I'd be getting GPM not MPG. To me 8 sounds like a good number for such a big vehicle with that big a motor and such low gears. My dad has an 84 chevy dually with a 454 that only gets around 8 loaded or unloaded.