What is your actual mpg(local drivers that haul for quarries)

[dds92780]

Ok, I know i will never get the right answer because it all depends on the engine, the gearing, the traffic, the weather etc but lets at least try to get some real world scenarios here.

Try to do it in the same format as me.

Mack RD 688s

e7 350 mechanical (turned up, prob more than it should be , oversized injectors)

442 rears

grossing 73000, running empty back to pit or next job

Mixture of stop and go driving from 0 to 50

I feel that i am getting anywhere from 5.0 - 5.5

I will say that since i have turned up the pump and put bigger injectors in, the truck is a beast but i think i pay for it at the end of the day (im guessing another 4-5 gallons) (which is why i think i should get a bigger exhaust or just turn the pump back down at least half)

Lets hear what you got

[bts-4120]

that much stop and go 5.5 doesn't sound too bad you ever figure how many gallons per hour your burning?

[dds92780]

I'm going to be doing stop and go driving again tomorrow and i will try to keep the rpms low and see what i can muster out of the dog. I'll post tomorrow

[Baxter]

Maybe you could try getting better milaege by trying to do a better job of feathering the throttle. I have a 2000 CH hauling a tri axle flow boy . 23 miles one way to quarry. Gross about 100000. 4.75 to5.5 mpg. Oh yeh 460 18 speed with 4 something rears. Not much help but take it easy for a week, quit cowboying it and it will do better and last longer.

[Dirtymilkman]

My trucks haul milk off of dairy farms. 10-12 pickups on a load then 70 miles on 70 mph interstate to the plant. The old '96 cl with 427, 18 spd, 3.86 rears and stage 2 injectors will average just under 8 mpg. Gross 79,000 when full. The 2001 cl with 460, 18 SPD, 3.86 rears and stage 2 injectors will do 6.8-7.4 mpg. The 2015 titan with a 525 18spd and 3.70 rears right now is averaging 6.2 overall. He grosses 89,000.

I was taught when you drive you pretend there's a egg between your foot and the throttle. Don't crush the egg! But I have noticed that the quicker you get to cruising speed without stomping on the throttle the better your mpg is.

[dds92780]

Ok so i started the truck at 430am , let it idle for 30 mins ( i dont usually let it idle this long) got to the pit, sat in line for 10 mins, then took my first load, then talked to the redimix manager for 5 mins, then went to another pit, was in there for 20 mins, then got stuck on interstate 55 for 20 mins, then everything was going smooth, then i got stuck at another road under construction for 15 mins. I babied the truck all day. I would use the method of pretending there is an egg between my foot and use literally .35 throttle or so, but when the rpms are low around 11 i would give it just a lil more to get it up to 1200 at 25 psi or so and then just hold 15-20 psi to 1500 rpm then shift. I did this all day long. The truck makes good power down low with the new injectors that i can give it just enough fuel to get the turbo spooling and then baby it.

My results were 284 miles with 49 gallons.

I ended up with 5.79mpg today which i don't think is bad considering all the stop and go and traffic jams i dealt with today. I am going to try for 6 tomorrow

I also came to the conclusion that 350 hp is all you really need. It is good to have bigger injectors though i think but you really only need 15-20 pounds of boost to get work done. The injectors help it get there faster though. I wonder what would happen if i turned down the pump halfway to what it is already. You think it would help or just leave it the way it is?

[mrsmackpaul]

Interesting enough back in the late 70's they had fuel trials almost every month in the "Truck and Bus" magazine fuel trials might not be the right word anyway they did truck test and they had a Mack with I think from memorey 300 coolpower with a 12 speed and I reckon it got close to 7.5 MPG it had a triaxle tipper grossing around 38.5 tonne so that would have to be around 85000

I could find the artical if you like and post it in here

Paul

[hicrop10]

With all this talk about 5-7 miles per gallon is getting me excited.Now i know my old truck doesn't have all the power of these new trucks but i will put the old girl up against anything on the road.I have a 335 cummins,triplex trans,65,000 rears.The ratio is 9.05.I get in around 3mpg empty loaded 1-1.5mpg.I can remember running out to a job we had outside of Baltimore MD,in Hunt Valley Md.We would run out rt 30 from Philly to York,PA then we would take Rt83 down to the state line.We make it out with the load but would have to get fuel before we headed home.I have the truck in the shop now doing it over.It's a 1964 Mack B873SX.Been in the family since new,wouldn't trade it for nothing.Oven in the summer,icebox in the winter wouldn't have it any other way.

[Mackpro]

Our dump truck guys here with the CV's and CT's with the AI engine are getting 4.9 to 5.2 total average, with 5.3 being the highest I've see. The older RD's and CV's and CL's with the regular ETECH engines get a little better. My friends 2013 GU with a 415C MP-8 with 22,000 miles on it is getting 6.2 going down the road, 6.6 in cruise and 9.0 in the sweet spot. However his idle time and PTO time bring him down to 5.8.

[bts-4120]

9.0 is quite a sweet spot what is that empty and all down hill?

[dds92780]

Keep them results coming guys.

So today i had a TON of hills, and even some offroad work was involved but i still only used half throttle and let it get up to 25 pounds of boost at times on the long hills. 800 on the pyro was my was on a long climb. I even got it to hold steady at 600 while loading and cruising at 50. Still can't figure out why my boost gauge is fluttering under 1400 rpm while building boost at only partial throttle or full throttle. It sounds like a miss but i still build boost. It goes away after 1400 rpm. I do have a small exhaust leak just under the muffler and the pipe that connects to it. You don't think this could be causing the issue do you? I just changed the fuel filters and that didnt fix it.

Anyways, back to the topic. I ended up going 277 miles and burned 50 gallons. The total is 5.54 which i am actually pleased with considering how many long climbs i had and the amount of offroading driving i did

[Dirtymilkman]

Someone once told me if your boost gauge flutters, move it to another port on the intake. They said you can get turbulence from out of the head

[rsb502]

one thing is missing here, what size drive tires do you have? 4.42 rears with 11R24.5's is pretty much the standard here and I averaged 6.8 doing the math in my 04 Granite, my friend does the same with his tri axle, all grossing 74,000#. actually two things are missing, what trans are you running? OD or Direct, Mack or Eaton, .74 or .68 or .62 OD? all this comes into play. Id leave it alone, you got almost 6mpg letting it run all day sitting in traffic and I always shut ,ine off if it sat more than 5 minutes so i saved a ton of fuel there. Also just because you are using half throttle doesnt mean your only using 350hp, you have more torque than stock now with the pump work and injectors and the torque is what does your pulling down low. I think if you just ease into the throttle and let the truck do the work, keep it under 20- 25# of boost (unless you can pass a cat) youll be happy with it. I had 4.42 rears on low pro 24.5 tires in my 84 Superliner, E9 440hp V8 turned up a bit with a Mack trtxl 1070 . It was geared steep for the highway and I pulled containers and dump trailers but if i did more driving under 55-60mph than over 65 i averaged 6.2-6.5 but I never used more than half throttle unless I was teaching a pete a lesson on a hill. leave it alone and give yourself some time to get used to driving it, youve onloy had that done two weeks now, itll take time to learn how to drive the new hot rod parts to get the most out of them.

[dds92780]

one thing is missing here, what size drive tires do you have? 4.42 rears with 11R24.5's is pretty much the standard here and I averaged 6.8 doing the math in my 04 Granite, my friend does the same with his tri axle, all grossing 74,000#. actually two things are missing, what trans are you running? OD or Direct, Mack or Eaton, .74 or .68 or .62 OD? all this comes into play. Id leave it alone, you got almost 6mpg letting it run all day sitting in traffic and I always shut ,ine off if it sat more than 5 minutes so i saved a ton of fuel there. Also just because you are using half throttle doesnt mean your only using 350hp, you have more torque than stock now with the pump work and injectors and the torque is what does your pulling down low. I think if you just ease into the throttle and let the truck do the work, keep it under 20- 25# of boost (unless you can pass a cat) youll be happy with it. I had 4.42 rears on low pro 24.5 tires in my 84 Superliner, E9 440hp V8 turned up a bit with a Mack trtxl 1070 . It was geared steep for the highway and I pulled containers and dump trailers but if i did more driving under 55-60mph than over 65 i averaged 6.2-6.5 but I never used more than half throttle unless I was teaching a pete a lesson on a hill. leave it alone and give yourself some time to get used to driving it, youve onloy had that done two weeks now, itll take time to learn how to drive the new hot rod parts to get the most out of them.

I agree but i still can't figure out why it feels like it has a miss in the lower rpm building boost. I can hear it out of the passenger window too on a hard hill pull in the top gears. Antrim told me that i might need to redo the governor springs in the pump. There are three of them and to get oem ones again. I doubt that is the issue though. I just changed the fuel filters and nothing changed yet.

[Dirtymilkman]

Exhaust manifold leak??

[dds92780]

The problem fixed itself today. Hear is what i think happened. There is something called a lift supply pump on the side of the bosch mechanical pump. If it is faulty you will notice longer starts in morning or when changing fuel filters you will have to give it some pedal to keep it running till its full enough. I believe there was air trapped in the pump somehow or something. Either way, all the fluttering of the boost gauge and the feeling of it missing are gone now. I get a smooth 32 pounds of boost by 1300 again. Long story short, I drove it fairly easy and had a ton of traffic and hills but kept speed at an average of 40-50 along with crawling speeds for traffic and still averaged 5.7. I shift to 1200 only in low gears and 15 in high gears. I try to build up boost and then hold it at 20-25 and i still walk away from other trucks lol. They dont know i have more bark in the dog if i want to too. I am happy with that I still think i need to order another lift supply pump though.

[mrsmackpaul]

well had some spare time today so I had a look see at what figures I could find

In 1968 Truck and Bus did a road test between Melbourne and Sydney for people that dont no thats around 800km proberly 850 km crossing the Great Dividing range twice thats the main mountain range on the eastern sea board of OZ runs top to bottom of the main land anyway it was one the first 4 Maxidynes in OZ pulling a pantec I think it said gross weight around 32 tons it averaged 6 MPG neat

The truck test I was thinking of was in 1978 300 Maxidyne with 12 speed OD 5.02-1 ass end gross 35 tons it got 5.5 MPG on its test, the company that owned the truck said that it averaged around that but had got as good 7 MPG

In 1981 there was a Cruise Liner with a E6 - 350 12 speed 4.64 ass end pulling a double deck stock crate gross weight 39 tons got 5.1 MPG which isnt to bad considering pulling a double crate is like pulling a big parachute behind you

I my self cant give you anything special because I dont have a tipper but cruising around local work with a float "lowloader or maybe low boy" I would have expected around 6.5 MPG with a semi with a high load 5.5 MPG road train doubles about 80 tons around between 5 and 5.5 a lot depends on were you are as in open plains or trees and hills open plains really sucks the fuel I have been down to 55 - 60 km/h across the Hay plains in NSW and once I get up into the scrub and few hills in Queensland I cruise at around 80 - 85 km/h same load just a bit further north

my Mack is a 320 cool power ( Thermodyne ) 12 speed OD 5.73 ass end

So I guess all this dosnt mean much but the one common thing I have to say is these older motors out perform the new trucks just little bit slower but by far a lot cheaper to run and to bye kinda makes me wonder why they stopped making them but thats a whole other storey

Paul

[TorresTransport]

Chicagoland dump trucking stop and go traffic all day everyday CHN613 427 E7 I get around 5.2 to 5.5 with gross of 73,280