Ram Cummins Vs GM Duramax Ike Gauntlet

In previous Ike gauntlets, a 2015 2500 Cummins flew up the Ike towing 12k V-nose trailer with an additional 500 lb tote in the bed. It stayed in 4th gear at around 2,250 rpm doing 65 mph most of the way to get a time of 7:33 and the exact same fuel mileage reading as this run.

That truck was identical to this truck in except that it was 2wd so I have no doubts that the 2017 truck in this test(along with the others) can easily do 65 mph if they wanted on the less steep parts. So they all are capable in burning the amount of fuel needed to make enough power to get the weight up the hill at 60 mph. The only difference is that each were forced to run at a different rpm due to their gearing.

I think Fish was applying gas engine physics to a diesel with his statement earlier.

In the Ford video, Mr. truck says he was at WOT near the end, so at least one truck was at max performance. Given how they all perform so close, I'm sure the others were likely floored at the same spot (if traffic conditions allowed).

Groover wrote:
"I can guarantee you that the DPF's were getting hot enough to passively regen up that hill. Anytime you are at high load for periods like that will trigger a passive regen due to the DPF getting hot enough without the use of extra fuel."

Are you saying that a "passive regen" is an actual event to the engine or simply that due to running the engine so hard the filter got hot enough to self clean and no further action by the engine management system was necessary?

If they had followed this piece of advice " I am not too fond of pulling a load like that up a hill at 1,600 rpm and would rather be in the 1,800-2,200 rpm range to keep EGT's as low as possible." would that have killed the passive regen?

A passive regen occurs when the exhaust gets hot enough to ignite the ash in the DPF without any assistance from the engine such as injecting extra fuel. This is usually around 850F which can be achieved with constant half throttle and moderate boost. Diesels can easily get to this temp just towing a 10k on flat ground or just going up a hill unloaded. Most diesels are between 400F-700F when not towing an not going up steep grades so they do not get hot enough and need the engine to active regen(inject fuel) to get the DPF hot enough.

Keeping EGT's as low as possible pulling a load like that up the Ike means keeping them below 1,200F if possible. Those trucks are probably in that range if not higher with a constant load on the engine in the test.

I found this video that will explain what I mean. He is able to reach 800F+ both post turbo and post DPF towing a much lighter load on flat ground. RAM 6.7 Cummins - EGT vs RPM - Lugging

If you look at other videos he has done about regens, you will notice how low EGT's are when not towing under a steady load so an active regen is required in those occurrences.

I have to disagree about the times not being about horsepower available. The road they use for the Ike has constant grade changes from 3% to 7%(check for yourself here road elevation map) and the inconsistency of a human (Mr Truck) foot will cause the truck to constantly loose and gain speed. There is also a very steep part at the very top and flattens out as you come to the lights at the end. Neither truck would not be at a constant 60 mph the whole way up even if you put it in cruise control.

According to how much torque each truck makes at certain rpms, I can guesstimate that the Ford has 400 hp at its disposal at 2,500 rpms, the Cummins has around 300 hp available at 2,050 rpms, and the GM has around 275 hp max at 1,600 rpms.

The next time you tow a heavy trailer, put your truck in cruise control coming up to a steep hill and you will notice that you will loose some speed as you start up the hill and will have to apply more throttle to get back up to speed. Do this in 6th, 5th, and 4th gear and tell me which gear allows you to recoup that speed quicker. I bet you it will be 4th when you are making the most horsepower.

This is why truck drivers will downshift as they are coming to a steeper grade to get their rpms up so they will have enough horsepower to maintain speed.

"I can guarantee you that the DPF's were getting hot enough to passively regen up that hill. Anytime you are at high load for periods like that will trigger a passive regen due to the DPF getting hot enough without the use of extra fuel."

Are you saying that a "passive regen" is an actual event to the engine or simply that due to running the engine so hard the filter got hot enough to self clean and no further action by the engine management system was necessary?

If they had followed this piece of advice " I am not too fond of pulling a load like that up a hill at 1,600 rpm and would rather be in the 1,800-2,200 rpm range to keep EGT's as low as possible." would that have killed the passive regen?

The times up the hill have absolutely nothing to do with "most horsepower". The trucks were driven at the speed limit. Mr. Truck's right foot determined how long it would take for the truck to make the run. If one of the trucks had a speedometer that read 60 mph when the truck was actually travelling 61 mph and another truck had a speedometer that read 60 mph when the actual speed was 59.5 mph the difference in time up the 8 mile run (if Mr. Truck did a perfect job of holding the truck to an indicated speed of 60 mph) would be 12 seconds. The fuel economy was not accurately measured and is too close to call on the GM vs Ram test. GM should change their design for the tow hooks. I have not driven a GM lately but I am sure it is not too difficult to get the exhaust brake to work. If Mr Truck wanted to tell the truck to hold at 50 mph he should have used the cruise control. If he wanted to control the speed manually he should have controlled it manually.....likely just touching the throttle for less braking and releasing the throttle fully for more braking would have worked wonderfully.

I am not sure who you are speaking of here, but there is actually more to it then that.

You see, everyone's REAL WORLD is different which is why these trucks have so many different options like rear gear, transmission, or engine to fit each persons REAL WORLD. These trucks are made for many different uses and what may be best in your REAL WORLD may not work best in another.

You may like to drive at 70 mph when towing while another may be more comfortable at 55 mph. You may tow 12.5k while someone else may tow 10.5k. You may tow a 5th wheel while someone else may tow a less air resistant bumper pull. All of these different REAL WORLD scenarios would effect how each of these trucks would react and the fuel mileage they would get.

This is why I try to apply actual logic and reason to the outcome instead of just GM, Ford, Or Ram fanboyism. In this specific scenario, it is a no brainer that the GM truck got the best fuel economy per the computer since it had the least amount of injection events(lower rpms) followed by the one making the next lowest rpms(the Ram) and last was the one making the most rpms(the Ford).

It is also a no brainer truck making the horsepower(the Ford) due to being at higher rpms got the best time followed by the second truck making the most horsepower(the Ram), and the finally the one making the least amount of horsepower(the GM). Having lower horsepower available at the rpm each were at means it would be a little slower or quicker at recouping any loss in speed as the grade changes throughout the test.

Although each of these trucks were so close that statistically speaking there is no difference between them or enough to claim that one is a winner here. In my opinion, I don't see any of them as a winner and just enjoy seeing how great each truck easily handled the weight going up an extreme road while being able to maintaining the speed limit. That in itself is a win to me.

I just love the misled excuse posters and their "we know better than the designers and engineers who had produced the performance aspects for any of the pickups etc they can even buy"! Facts are something the excuser's have so little knowledge of as shown with their "funny" posts!

When 3 runners or sprinters line up for a distance run and one wins it's because of being the fastest and best of the 3. DUH! That's what head to head competition always reveals and not lip service or finger typing or what iff's!!! What is, is and all the excuses will never change that outcome!

Some manufacturers have done a better job of producing a more efficient and better performance pickup for REAL WORLD use and some didn't. It's in REAL WORLD comparison equal parameters tests and competition that is where the differences are revealed over and over! Carryon boys!

ib516 wrote:

I agree, they RPM "data" is useless unless we know the camera was on the gauges when the trucks were on the same spot on the hill. The grade varies.

As I stated in my initial post regarding this, I was just going based on the limited screen shots we had and the knowledge of how much rpms play a role in fuel economy when I was at Cummins.

The same logic is applied to why taller rear gears gains better fuel economy because they keep you at a lower rpm. However, in this case due to the Ford and Ram having taller rear gears, they ended up having shorter final ratio due to being in 4th versus 5th in the GM

With this, it should be a no brainer that the GM truck had the best fuel since it was at 1,600 rpm in 5th giving it a combined final ratio(5th gear+rear gear) of 2.65:1. The Ram was second best hovering around 2,050 rpm in 4th with a final drive ratio(4th gear+rear gear) of 3.42:1. Then the Ford in third being at 2,500 in 4th with a final drive ratio(4th gear+rear gear) of 4.05:1. More rpms means more injection events per minute so if each engine is at 100% load, then the one with least injection events or volume per event(which should be very close with these engines with the Cummins having the slight advantage) will burn the least amount of fuel.

Also, as TnP stated earlier,a heavier or lighter load might have changed the outcome. So would a higher or lower speed. If they would have lowered the speed to 55 mph and forced the GM to downshift to 4th as well then the Ram would have had the least rpms and tallest final ratio. If they would have increased the speed to 65 mph allowing the Ram to have enough rpms to shift into 5th then the Ram and GM would both be hovering around 1,800 rpms and very close final drive ratios. This is assuming that each were making enough power to drive at these speeds with that load. From the videos, it is clear that they do.

So all 3 - Ram, Ford, and GM were just a hair over 8 minutes and between 4 and 4.5 mpg. Nobody really has a performance advantage at 12.5k lbs.

The TFL guys would have to go with heavier weight to separate the trucks in terms of performance.