30,000 lbs behind the Ram

4x4ord wrote:

jmtandem wrote:

It just doesn't make sense. You let up on the accelerator to tell the truck you want it to pull harder??? Obviously if the engine is revving high, letting up on the skinny pedal will encourage it to upshift. I think Mr Truck has been sucking in too much diesel smoke.

Watch the F 450 video beginning around six minutes. The discussion is all there. Another interesting thing not mentioned on the F 450 video is that many auto insurers stop at 350/3500's. Getting a 450 might require finding an insurance company like Progressive that will insure it. And, lastly, while a very nice truck, the payload mentioned by the testers was around 4500 pounds. For a 450 dually that is incredibly low, lower than my Ram 3500 dually. The 450 may be built to tow more but not haul more, for example, a cabover camper. Also, interesting is that the 30,000 pound trailer has a gooseneck that is around seventeen percent tongue weight or close to 5000 pounds, plus two occupants.

Yup, I heard the statement..."if I let off the gas it would downshift" I'll stick with my interpretation of that statement.

A lot of trucks will "downshift" if you let off and back on. It's not downshifting though but unlocking the torque converter. My 2005 Ram does it and my 2006 F350 does it. I've never paid attention to see if my 2013 or 2016 Rams with the Aisin does it or not. I'll have to see the next time I'm in it.

jmtandem wrote:

It just doesn't make sense. You let up on the accelerator to tell the truck you want it to pull harder??? Obviously if the engine is revving high, letting up on the skinny pedal will encourage it to upshift. I think Mr Truck has been sucking in too much diesel smoke.

Watch the F 450 video beginning around six minutes. The discussion is all there. Another interesting thing not mentioned on the F 450 video is that many auto insurers stop at 350/3500's. Getting a 450 might require finding an insurance company like Progressive that will insure it. And, lastly, while a very nice truck, the payload mentioned by the testers was around 4500 pounds. For a 450 dually that is incredibly low, lower than my Ram 3500 dually. The 450 may be built to tow more but not haul more, for example, a cabover camper. Also, interesting is that the 30,000 pound trailer has a gooseneck that is around seventeen percent tongue weight or close to 5000 pounds, plus two occupants.

Yup, I heard the statement..."if I let off the gas it would downshift" I'll stick with my interpretation of that statement.

jmtandem wrote:

Why is it odd?

From your own figures the Nissan made more HP up to about 9,000 ft. By then the Nissan was so far ahead that they beat the oil burner up the hill.

It would be informative to learn what Cummins would have to say about the test. By way of information the Ike grade is an almost constant seven percent, perhaps the steepest grade for eight miles of any interstate route. Also, the Ike gauntlet tops out at 11,100 feet and the test begins at around 9000 feet. So, the gasser would be down close to twenty percent of it's sea level power. The Cummins should make almost sea level power at 11,000 feet since it is turbocharged.

The Titan Cummins is rated at 310 hp and 555 foot pounds torque, basically all power is available up to the summit/tunnel. The Titan's Endurance gasser is normally aspired and comes with 390 hp and 409 foot pounds torque. At 9000 feet, the start of the test the gasser has lost almost twenty percent of it's sea level power so it would start the test at 312 hp and 327 foot pounds and at 11,000 feet the numbers would be 27.5 percent lower; or 283 hp and 296 foot pounds torque. The seven hp for the additional 1000 pounds should not have made that much of a difference.

I noticed that it was mentioned that the Ike is a nearly consistent 7% grade. It's not though. I read somewhere that the elevation gain is 2225 feet (it is no more than that anyway). 2225 gain over 8 miles is only an average grade of about 5%. According to this website the maximum grade is 6%.

It just doesn't make sense. You let up on the accelerator to tell the truck you want it to pull harder??? Obviously if the engine is revving high, letting up on the skinny pedal will encourage it to upshift. I think Mr Truck has been sucking in too much diesel smoke.

Watch the F 450 video beginning around six minutes. The discussion is all there. Another interesting thing not mentioned on the F 450 video is that many auto insurers stop at 350/3500's. Getting a 450 might require finding an insurance company like Progressive that will insure it. And, lastly, while a very nice truck, the payload mentioned by the testers was around 4500 pounds. For a 450 dually that is incredibly low, lower than my Ram 3500 dually. The 450 may be built to tow more but not haul more, for example, a cabover camper. Also, interesting is that the 30,000 pound trailer has a gooseneck that is around seventeen percent tongue weight or close to 5000 pounds, plus two occupants.

jmtandem wrote:

"We need Cummins to comment, but the only reason I can imagine for why the transmission would downshift by letting up on the accelerator on the uphill run is because the truck would have lost some of its speed... "

The testers basically said the same thing (letting up to downshift) about the F 450 test when they felt it should shift down climbing and the truck was still in the higher gear, lower RPM's, and slower speeds.

It just doesn't make sense. You let up on the accelerator to tell the truck you want it to pull harder??? Obviously if the engine is revving high, letting up on the skinny pedal will encourage it to upshift. I think Mr Truck has been sucking in too much diesel smoke.

Why is it odd?

From your own figures the Nissan made more HP up to about 9,000 ft. By then the Nissan was so far ahead that they beat the oil burner up the hill.

It would be informative to learn what Cummins would have to say about the test. By way of information the testers state the Ike grade is an almost constant seven percent, perhaps the steepest grade for eight miles of any interstate route. Also, the Ike gauntlet tops out at 11,100 feet and the test begins at around 9000 feet. So, the gasser would be down close to twenty percent of it's sea level power. The Cummins should make almost sea level power at 11,000 feet since it is turbocharged.

The Titan Cummins is rated at 310 hp and 555 foot pounds torque, basically all power is available up to the summit/tunnel. The Titan's Endurance gasser is normally aspired and comes with 390 hp and 401 foot pounds torque. At 9000 feet, the start of the test, the gasser has lost almost twenty percent of it's sea level power so it would start the test at 311 hp and 327 foot pounds and at 11,000 feet the numbers would be 27.5 percent lower than sea level; or 280 hp and 296 foot pounds torque. The seven hp needed for the additional 1000 pounds the diesel towed should not have made that much of a difference.

The difference must be in the rear end ratios or the transmissions. Just watching the test it would be hard to spend the extra money for the diesel (unless you just love diesels) as it's performance was not that spectacular and it only got about twenty percent per gallon better on the wide open throttle climb.

"We need Cummins to comment, but the only reason I can imagine for why the transmission would downshift by letting up on the accelerator on the uphill run is because the truck would have lost some of its speed... "

The testers basically said the same thing (letting up to downshift) about the F 450 test when they felt it should shift down climbing and the truck was still in the higher gear, lower RPM's, and slower speeds.

"We need Cummins to comment, but the only reason I can imagine for why the transmission would downshift by letting up on the accelerator on the uphill run is because the truck would have lost some of its speed... "

I agree.

I have tried all different ways of towing. The trans/engine know what gear to be in when climbing a serious grade. On a big grade I just hold it to the floor and it will downshift when needed. I have manually dropped a gear and it made no difference or lost speed so I let it upshift. My 11 HO with 68RFE was different it seemed to pull better in the higher rpm's. This 15 with Aisin pulls strong at 2100-2300. Temps with this truck are never an issue even when pulling 14 percent with 33K combined. The trans and engine run cooler than the 11 did.

Turtle n Peeps wrote:
Why is it odd?

From your own figures the Nissan made more HP up to about 9,000 ft. By then the Nissan was so far ahead that they beat the oil burner up the hill.

The base of Eisenhower is about 9200'.

Using the 2.5 % power loss per 1000 feet of elevation above sea level the gasser should have been making peak power of 303 HP at 10,000 feet. The diesel is rated at 310 HP. The power required to lift the extra 1000 lbs up 2225 ft in 10 minutes is 6.7 HP. So I would have guessed the two trucks to have had similar times. But, I would have guessed the six gears in the diesel to give a little better results than 7 gears in the gasser.