The Cummins soon to take on the Ike

[4x4ord]

Time to place our bets;

I still haven't decided whether the Duramax did lousy or if the Ford is an over achiever. Ignoring the performance of the Duramax I'm going to say the Cummins will do the run in 10 minutes 50 seconds. it will be interesting.

Click


Edit: The more I think about it, the more I think the Powerstroke is under rated and the Ram will run the hill in the same time it took the Duramax .... 11:47

[Cummins12V98]

As far as the rough ride goes it appears the RAM will not have the Factory Rear Air Option as their recent test trucks have had. BUMMER!

[4x4ord]

^^^ I guess we should have the numbers soon. I'm alway amazed at how terrible my fuel economy is when hauling equipment. The other thing I've experienced is the horrible ride quality that they experienced with the Duramax and Ford while towing the equipment trailer. I have had some success in repositioning the load to smooth out the ride but I wonder if some of the ride issue isn't caused by wind buffeting?

[ShinerBock]

I am not sure about the heavy equipment trailer having that much more wind drag than the horse trailer. Wind will go through the back section on that horse trailer and hit that back door causing a significant amount of resistance. I know it makes a huge difference with similar cattle trailers of having a open gate back door versus a having a tarp covering the back doors. Not saying either trailer has more or less wind resistance because I don't have all the data, but that close back door horse trailer is probably creating more wind resistance than some think.

[4x4ord]

FishOnOne wrote:
I think we have already seen a preview of what the 2020 HO cummins will do. It was essentially a tie with the Duramax although some will argue it was a DRW therefore packing more weight.

What I'm really interested in is the HO cummins fuel economy towing 30k at this point.

did you see this?

8.7 towing 29000 lbs at 70 mph. Not nearly as much drag on the horse trailer vs pulling a trailer with heavy equipment on it. At 70 mph drag is huge pulling a load like the Ford and Duramax towed. The Cummins will likely come in pretty close to the Duramax on fuel economy.

[4x4ord]

rjstractor wrote:

RoyJ wrote:

If you read his post again, it's flat *power* curve, not torque curve.

A falling torque curve is desirable in a heavy duty motor, because as you lug down the revs in a gear, you get torque rise, thus fairly constant power.

The Cummins loses less power at lower rpm than the Duramax, and thus won't need 10 speeds nearly as much.

Exactly, the motor with the flat power curve maintains horsepower when shifting to the next higher gear, whereas the motor with a flat torque curve loses horsepower with every shift. The extra gear ratios help minimize this.

Roy is pointing out that an engine with a high torque rise is nice for pulling because as it pulls down the torque increases. It's more about downshifting than upshifting. If you think of a heavy truck climbing a hill most of the rear wheel torque demand is determined by the weight of the load and the incline of the hill. To a much less degree the wind and rolling resistance come into play. Because of this fact, as the hill gets steeper and the truck slows down there is only a slight decrease in the torque demand. If as the engine pulls down the torque does not increase the hill wins. The only way the truck can get the needed torque to the rear wheels is if it slows enough to grab the next gear. On the other hand, under the same scenario with an engine which posses a high degree of torque rise, as the truck slows the engine pulls down delivering more torque to the rear wheels to meet the increased demand of the hill.

If you think of a car accelerating down a track you see an increase in rear wheel torque demand the faster the car goes to meet the increasing resistance of drag. Keeping the torque curve high as the rpms increase is important for a dragster.

[wilber1]

rjstractor wrote:

RoyJ wrote:

If you read his post again, it's flat *power* curve, not torque curve.

A falling torque curve is desirable in a heavy duty motor, because as you lug down the revs in a gear, you get torque rise, thus fairly constant power.

The Cummins loses less power at lower rpm than the Duramax, and thus won't need 10 speeds nearly as much.

Exactly, the motor with the flat power curve maintains horsepower when shifting to the next higher gear, whereas the motor with a flat torque curve loses horsepower with every shift. The extra gear ratios help minimize this.

The power curve isn't "flat" either but it is more gradual.

I agree though, more torque at lower RPM's means more power at normal operating speeds and less shifting, even if you won't get up a hill quite as fast at WOT because peak power is lower.

[rjstractor]

RoyJ wrote:

If you read his post again, it's flat *power* curve, not torque curve.

A falling torque curve is desirable in a heavy duty motor, because as you lug down the revs in a gear, you get torque rise, thus fairly constant power.

The Cummins loses less power at lower rpm than the Duramax, and thus won't need 10 speeds nearly as much.

Exactly, the motor with the flat power curve maintains horsepower when shifting to the next higher gear, whereas the motor with a flat torque curve loses horsepower with every shift. The extra gear ratios help minimize this.

[RoyJ]

wilber1 wrote:
The last Cummins to have a flat torque curve was the 350 HP 650 LB/FT. in early 2011
It reached 650 lbft at 1600 RPM and stayed flat until peak power at 2800 RPM

The 350/800 engine reached 800 lbft at 1600 RPM but gradually decreased until it was the same as the 650 engine at 2800 RPM. If it was still making 800 lb ft it would be putting out 426 HP, not 350.

If the Cummons 900 engine was still making 900 lb ft at 2800 RPM it would be putting out 480 HP, not 385.

If you read his post again, it's flat *power* curve, not torque curve.

A falling torque curve is desirable in a heavy duty motor, because as you lug down the revs in a gear, you get torque rise, thus fairly constant power.

The Cummins loses less power at lower rpm than the Duramax, and thus won't need 10 speeds nearly as much.

[blofgren]

FishOnOne wrote:
I think we have already seen a preview of what the 2020 HO cummins will do. It was essentially a tie with the Duramax although some will argue it was a DRW therefore packing more weight.

What I'm really interested in is the HO cummins fuel economy towing 30k at this point.

At least we know the GM won’t have a hpfp disaster; this would likely be my new truck if I were currently shopping.

[Cummins12V98]

FishOnOne wrote:
I think we have already seen a preview of what the 2020 HO cummins will do. It was essentially a tie with the Duramax although some will argue it was a DRW therefore packing more weight.

What I'm really interested in is the HO cummins fuel economy towing 30k at this point.

The 2500 SRW GM should have smoked the DRW RAM. 10 speed, lighter weight, less tire drag and less wind resistance.

Mileage on all three in REALITY should be similar. Not enough of a difference to make a buying decision.

I hand calculate every tan by filling to the top. Solo mileage computer is .4 higher than calculated. Towing in mountains or strong headwind computer is right on or slightly higher. Never is the computer lower.

[FishOnOne]

I think we have already seen a preview of what the 2020 HO cummins will do. It was essentially a tie with the Duramax although some will argue it was a DRW therefore packing more weight.

What I'm really interested in is the HO cummins fuel economy towing 30k at this point.

[4x4ord]

^^^^ If it had 1000 lb ft of torque at 1800 rpm and 900 lb ft at 2800 rpm it could compete quite nicely with the Powerstroke.

[wilber1]

The last Cummins to have a flat torque curve was the 350 HP 650 LB/FT. in early 2011
It reached 650 lbft at 1600 RPM and stayed flat until peak power at 2800 RPM

The 350/800 engine reached 800 lbft at 1600 RPM but gradually decreased until it was the same as the 650 engine at 2800 RPM. If it was still making 800 lb ft it would be putting out 426 HP, not 350.

If the Cummons 900 engine was still making 900 lb ft at 2800 RPM it would be putting out 480 HP, not 385.

[blofgren]

Grit dog wrote:
Wishes for best possible outcomes in your life Larry. Sounds like you both have been able to enjoy the better things in life for more than a while and that is priceless.

x2.

[Grit_dog]

Wishes for best possible outcomes in your life Larry. Sounds like you both have been able to enjoy the better things in life for more than a while and that is priceless.