Hannibal

I remember an episode of Gunsmoke when Festus (sp?) said, " they ain't no need a gettin' awl torqued out'a shape about it now".

1sttruck

For hauling loads in motor vehicles that most of us use HP is a moot point, as it's like also saying 'the engine must cost less than $1,000,000 and not catch fire in the first 3 hrs of operation'. We can disregard all discussion of hp provided the torque is adequate, as if the torque is adequate the hp will be too. As we've demonstrated that is not the case when discussing hp.

Hannibal mentioned trying to use a high torque/low rpm (500) engine, and while I searched briefly I could not find such an engine. I figured that it might be a marine diesel, but the high torque engines still operated at rpms that we're use to and again also provide more than adequate hp. It was interesting that boat owners are having the same discussions that we are, as some were wondering why a small, low cost, high hp gas engine couldn't be used in place of a larger expensive, lower hp disel engine. The pundits were trying to explain that 'there is hp, and then there is real power.....' :^)

Hannibal

You couldn't find one because it doesn't exist for on road use. But that's my point. All the necessary torque but not enough horsepower (a procuct of torque at a high enough rpm to be useful), I still think we all agree. We just express it differently. Of course we want the most torque at the lowest rpm. To me that equates to the most HP at low rpm.
Engine dyno's measure torque at the rpm the motor is capable of from the crankshaft and horsepower is calculated from that twisting force. Chassis dyno's measure hp in the same fashion as the horse and plow example. How hard it pulls even though the road is a rolling drum. There are too many variables to accurately measure torque on a chassis dyno. But horsepower is a constant regardless of gear ratios to the rear wheels and torque can be accurately calculated from HP at a given rpm. Removing your motor to put it on an engine dyno would be a tad impractical.
The boat people should realize that although the smaller higher rpm higher "peak" horsepower gas engine is rated for more horsepower, it's at an rpm that's hard to reach without low rpm torque aka low rpm horsepower. The high torque at low rpm equates to higher horsepower at the lower rpm than the higher peak horsepower low torque motor. For the boat or the heavy truck, the heavy duty high torque at low rpm which equates to higher horsepower at that lower rpm than a Lamborguini, is better suited for towing.
Look at my signature. I fixed my cussed vibration. I can't opt for a PSD or Dmax. I'll be reaching for horsepower at a thousand rpm higher than I've been used to with my past four Cummins engines. I'll have to use gear reduction to make torque that my Cummins made at it's lower rpm. It'll do it. At about 30% more fuel consumption and for not more than maybe 150k miles. But I trade every two to three years anyhow and hopefully by then Dodge will have figured out how to use the mighty Cummins in a pickup truck without issues and bandaids to make it right. I'll never buy the first year model vehicle again and never any vehicle without driving it on the interstate first.
If Dodge can beef up the 545RFE that's in my new truck to hold up to the torque of the Cummins like they did in only16 years with the 727(sarcastic insinuation), THAT will be sweet! It has a real tow/haul mode and two O/D ratios. It even has two second gear ratios. One for upshifts and one for downshifts. It's a 5spd but actually has six forward ratios to work with. It downshifts on it's own on the downhills to hold back speed even empty and it feels like it locks the TC when it does. Hopefully a sign of things to come when I'm ready to buy again. Until then I'll be runnin' around 2800-3000rpm flat and around 4200rpm uphill towing. You wouldn't believe how smooth and quiet the Hemi is at those rpm. But then again, you couldn't care less so I'll enjoy it while I have it!

Racnmasn1

INTERESTING TOPIC, Learned so much! However, getting my Bachelor degree I had to take a few science classes, where I learned Diesel fuel has 30% more energy then regular gasoline, I didn't see where any of these smart guys addressed this in any of their threads.

Hemi or gasoline engines are already trying to catch up to diesel. It is in fact an inferior fuel compared to diesel.

I also can't believe the majority of environmentalist don't address this. They all want new costly alternative fuels. Amazing diesel is just sitting here not getting any attention.

And when I say "smart guys" I mean it.


Racnmasn

supr

It seems that the Feds are causing major problems for manufacturers.. The sulfer content is being reuced significantly in the next few years. diesel emissions wil have to be cleaned up further. How this will impact Cummins & this class remains to be seen. For cars, it appears most manufactureres are willing to just do gas because Diesel presnets too large a hurdle at this point. An interesting article I have not read in this months Car & Driver about Diesel Hybrids being a fuel effient solution, but they wil have the same issues.
When this thread finishes, the laws of physics wil prevail. Cummins=Torque & HP. You gears & milage may vary.
In Europe, over 1/2 of the cars are diesel, due to tax on gas & better economy. Their governments seem to think it is the lesser of the eveils.

RustyJC

Nor did we discuss the inherent specific fuel consumption advantages of the Diesel's higher expansion ratio versus an Otto-cycle engine, the fact that the Diesel engine's pumping losses are lower due to the lack of a throttle plate, etc. The thread wasn't originally about every design advantage of a Diesel engine, Diesel fuel, etc. - rather, it was discussing optimum RPMs when towing.

Rusty

Hannibal

I guess that would coincide to my now 30% less fuel efficiency and 30% higher rpm to do the same job my S/O Cummins did. I think Cummins is already ready for '07 with the ISBe. Shouldn't be a problem. The problem might be the cost of the new ultra low sulfer content diesel fuel. So now that I'm burning gas I'm poluting more? What a hoot!