Does the torque rating really effect mpg?

depends on driveline specs and whether you're at max weight all the time. You can spec a lightweight drivetrain @ 1650.

 

It will come Doreen to how you drive it. Drive it with good smart decisions controlling that right foot and you won't notice an increase in fuel consumption. If you act like your on the drag strip at every red light then your gonna be doing for fuel every few hours.

Big engines can get good fuel economy if you use your head.

 

You won't have an advantage on the higher momentum if you don't use it. Like stated above, take it easy and run the engine as close as possible to it's maximum torque output, and that's around 1200 RPM or even lower.
And yes, there is a difference between 1650 and 1850.
Higher torque = higher MPG.

 

It take more fuel to make more power but you also do not need to be in the throttle as muvh to go any given speed with more power.

Its a trade off that needs self discipline. The more tq the more usable the truck is in a variety of situations but when you dont need it stay off the accelerater

 

Higher MPG like posted.
The engines HP is usually rated around 1800 RPM. Running the engine at this range, it kills the fuel mileage.
The engines most torque output is around 1200 RPM or even lower. Torque means pulling power at low RPM. As more you have available here, as less shifting is involved. Shifting means, interrupting the powertrain, loss of speed which needs to be accelerated again at the top of the hill. Loss of turbo boost which needs to be built up again. Shifting down also means shifting up again with the same effects.
You might not be as fast pulling up the hill on the torque side of the engine vs pulling up on the power side.
If you wanna win the race you have to rev up. But never ask about fuel consumption in a race track.

 

Think on this.

A engine has a torque rating at a certain RPM on the chart.

That rating is married to a horsepower rating which is defined as one horse worth of work lifting a certain weight in a space of a defined time. The higher the horse, more rapidly the engine can complete it's work. The RPM at max horse is above the torque.

The Torque is a point at which the load over comes barely the ability for the engine to run at all in a given gear, rear end ratio, wheel size etc. You can make a engine lug down below 1200 rated torque to say ... 900 but you would make that thing buck and shake and fight to stall against a mountain.

A badly driven or abused engine will break. Me it's usually going to be a thermal oil/manifold pyrometer problem if it is a aluminum not a steel engine. That is how I break them at high horse trying to drag over a mountain in double digit percentages that has to be experienced as a out of body experience which may or may not be your last day on earth, if your engine is too small, not enough torque and not enough horse.

Your drive shaft usually have a rating also. It is a torque limit that you can put on it. I remember spicer shafts were rated for 1350 where my detroit was maybe 1500 or roughly. If you lean into it too much sliding a trailer tandem... SNAP! No more drive shaft or universals. It's theoratically cheap to fix. But when taken into consideration with a repair call, heavy tow hourly rates like 600 per hour etc forget that peice of #### shaft your company nazi just shafted everyone spec'ing #### componets.

I want the most horse I can get.

Emissions steal horse. Put a medical mask over your nose and mouth and your power needed to move air just went up. It will tire you out. An engine is the exact same thing, It needs to breathe, burn and blow.

If a engine is made for 500 horse. leave the #### thing alone. Forget the extended warrantry.

Detuning a engine will make it labor harder, burn more fuel as you stagger up tinkletown pass 4% at 21 mph instead of cruising over at or near the speed limit. You will discover other problems in hill country, mountain work, or prairie winds that wont quit. Time. You are slow. Late and later and more late. *&^% that POS detuned engine.

Detuning is well and good if you wanna rip the 5th wheel off, throw a dump bed on there or turn it into a yard jockey etc a role not meant for over the road delivery of critical cargos in tight time schedules. You basically cut the nuts off the engine and hand the poor ####### a #### truck. You wont keep that driver for long.

Ive been in speed limited trucks, Ive been in detuned trucks Ive been there. They get #### thirsty gobbling fuel because Im standing on the ####### throttle in the lower gears trying to kick it up the pass. Then I spend all day throwing the top gear back down to lower gear, rev rev rev rev rev... you dont #### a desiel like that. You need it to be steady and smooth to cruise with the least amount of hourly fuel burn.

I said enough. Keep the original warrantry, put aside some money each month against a future in which you need either a new rig or a new engine. Life is not going to remain the same. Don't detune that engine and for god's sake don't buy a drive shaft too light or a torque rating too ####.

Always get the most you can buy in both torque and especially horse. You will find that you burn less fuel per hour in the mountains, windy plains or hill country.