Your average fuel economy in ATS.

[SmokeyWolf]

Everyone is going to downspeed powertrains with direct drive transmissions now. So low RPM's seem to be the way everyone is going now. I drove a Paccar with a downspeed setup and I was actually impressed with how it performed and pulled compared to a regular overdrive set up.

[EllieODaire]

More modern engines like the Volvo D13, PACCAR MX11 & 13, Detroit DD13 & 15, and Cummins X12 & 15 are built to operate at pretty low RPMs and their paired AMTs will happily lug them in certain situations, especially downsped models that have terrain maps programed in. This is normal. You don't need to take any of those engines over 1500 RPM unless you're engine braking down a hill or running a max power heavy haul spec.

[Space_Night]

and what about a DD 12v92 or 12v71 which are 2-cycle engines?

[SmokeyWolf]

What @EllieODaire said is correct. I only ran one downsped truck in my 12 year career and was actually impressed with it.

Old habits die hard, I'm use to running an engine over 1500 rpm pulling hills. That is just a habit of mine.

2 cycle engines have such a narrow torque band and their operating range was 1700 to 2500 rpm. The old saying goes when it came to 2 cycle engines was you had to slam your hand in the door and get mad in order to drive it properly.

[supersobes]

With my Cascadia in ATS, the DT12 picks a gear that my DD13 sits comfortably at 1,050 RPM at 55 MPH and 1,250 RPM at 65 MPH. It runs quite efficiently this way as I tend to average around the 7 MPG mark on most trips, which I think is quite good taking the map scaling of ATS into account.

I have the adaptative automatic transmission enabled in ATS, so it will pick when to shift depending on how I drive. If I'm light on the accelerator, it will move to the next gear between 1,400 and 1,500 RPM. If I'm pedal to the metal, it'll hold onto a gear until between 1,600 and 1,700 RPM. It's quite a nice feature for having power available when its needed, while running more efficiently when it's not. And of course, the feature that allows you to manually request shifts from the AMT is quite useful for managing power and efficiency.

[Space_Night]

@supersobes the DAF CF I drive for a day job has a 12spd gearbox, and at 56mph she sits at around 1500rpm

incidentally I have edited the defs for the megapack by Kriechbaum for the 12v71 and 8v92 to give power outputs at similar RPM ranges found here
https://www.barringtondieselclub.co.za/ ... -sheet.pdf

[Stealth Daemon]

well, i will stick with my setup for awhile but i started to shift the 18-speed by myself which is somewhat challenging when you´re not used to it... i´m still at 5,4 mpg btw.

since i´m not a truck driver myself, i asked my father how he did back then when he was trucking, but still seem more complex than i´ve thought.

note: i was a postman until some months ago and i have to admit that i only managed to go 400km with 75 liters of Diesel (due to the ongoing stop and go).

this should be around 250 miles with about 20 gallons of diesel.

@supersobes your setup sounds very interesting, i think i try something similar out.

wait, you can shift while you use automatic transmission? i did not know this is possible.

[Seifer1968]

Trucks with 6x4 traction generally consume almost twice as much compared to traditional tractions (4x2,6x2).
I speak from my real experience in Europe, with a 4x2 vehicle consumption 3.3-3.4 km/l, with a 6x4 we are talking about 2.2-2.4 km/l.
So now if I'm playing with a Kenworth T800 6x4, Cummins ISX EGR 500 engine and Fuller 3.70:1 10-speed gearbox, it's normal that it consumes 1.88 km/l with heavy towing.

[Stealth Daemon]

@Seifer1968

i did not know that it makes that much of a difference, but i have to admit that i drive practicially everytime a 6x4 chassis, but i guess a 6x2 is better for light loads also?

my father also drove 4x2 trucks most of the time.

[VTXcnME]

After seeing this thread a while back, I started checking my trip MPGs based off distance/gallons used standard (not the mpg's on the dashboard)

@supersobes I get the same with a Cat 800hp engine and Eaton 18spd manual. 7.3MPGs pretty consistently across my travels (I run the numbers when I finish a delivery)