Ram Cummins Vs GM Duramax Ike Gauntlet

transamz9 wrote:

4x4ord wrote:

travelnutz wrote:
As a nearly 40 year automotive engineer and automotive engineering operation owner, I sure as hell do know what I'm talking about! Taught many classes and you'd be wise to attend such! Torque and only torque is what and the force that turns the wheels to make the vehicle move at all or to any desired velocity and keeps it at that velocity also. Especially apparent on an uphill grade where torque does it all, all the time. Simple, as if you do NOT have adequate torque to maintain a desired velocity, the vehicle will drop in velocity.

Theoretical horsepower turns NO vehicle wheels nor does it apply one ounce of force to turn any wheel as horsepower is only theoretical calculation value. Torque is the only axle/wheel twisting force ever present! NO work is accomplished or done at all if there isn't adequate torque to make the wheels turn to any velocity. Try to deny this known well long time established FACT!!!

You've got your units confused. Asking how much torque is required to move a 20,000 lb truck up a 7% grade at 60 mph is like asking how may feet of gasoline it takes to fill your fuel tank.

Hp is a number used to tell you how much torque you need to produce at a rpm to achieve that speed. I think you guys are saying the same thing just have a different way of looking at the equation. How fast can you accelerate to 60mph up a 7% grade with 12.5k with 300hp? To answer the question you have to know how much torque you can apply through the RPM range. HP will just tell you the max speed it will achieve. If you don't have the ability to apply the torque needed to get the load to that max speed then max hp is useless.

Let's not get talking about acceleration yet. You are correct about a vehicle needing to put a certain amount of torque to the rear axle to move up a hill. So for instance a 20,000 lb truck/trailer combination parked on a 7% grade will have a certain torque on its rear axle. The lbs of force trying to roll the truck down the grade can be calculated by taking the sine of the arc tan of 7% and multiplying it by 20,000 lbs. It turns out to be about 1397 lbs. That 1397 lbs is pulling on the outside of the tire so if the truck has 34" diameter tires the torque arm would be 17" or 1.4167 feet. The torque on the axle is 1397 x 1.4167 or 1979 lbft. So the truck needs to be able to put about 2000 lb ft of torque to the rear axle in order to start climbing the hill.

Additional torque is required to overcome wind resistance if the truck is moving faster. So for instance to overcome wind and rolling resistance at a speed of 60 mph a truck/trailer will be consuming about 6 gallons of fuel per hour. (10 mpg) We know that 6 gallons of diesel contains about 327 hp hours of energy. If we assume a pick up truck engine is running at about 30% efficiency while running part throttle pulling a trailer down a level road at 60 mph we can figure that it takes somewhere in the neighborhood of 30% of 327 or 98 HP to overcome rolling and wind resistance of a typical 5th wheel traveling 60 mph.

So 98 hp are needed at the rear axle to travel 60 mph on level ground. If the tires are 34" in diameter then they will be turning 593 rpm at 60 mph. So 98 hp at 593 rpm means there will be 98 x 5252/593 or 867 lbft of torque on the axle to overcome wind and rolling resistance at 60 mph.

So the torque on the rear axle of the trucks going up the Ike would be in the neighborhood of 2847 lbft if they are to maintain 60 mph on the 7% grade.

In order to put 2847 lb ft of torque to the rear axle the Duramax would need to be putting out about 878 lb ft of torque at the crankshaft if the transmission is in 4th gear and assuming a 15% power loss while running with the torque converter locked up. The engine would be running at 2212 rpm and producing 378 crankshaft horsepower.


Edit: I should have used something a little higher than 30% for the the engine's efficiency to guestimate the power required to travel 60 mph on level ground. Maybe 38% would have been a better guess. So instead of 98 hp maybe 124 would have been a closer guess. If I add 26 rear wheel hp to the power the Duramax would have to come up with it would be 30 crankshaft HP. So the engine would have to be capable of 408 HP at 2212 rpm......or it would have to drop down to 3rd gear and rev to 3110 rpm (I don't lnow if the Duramax revs that high or not?) Maybe it would slow to 55 and run at 2850 in 3rd?

ShinerBock wrote:
Torque and rpm combine to make horsepower just like Crown and Coke combine to make me happy.

How much horsepower is being made depends on how much torque is being applied at a certain rpm just like how happy I get depends on how much Crown is being applied to the Coke.

Torque without rotational movement is useless just like Coke without Crown is useless.

You see, you can't have one without the other.

Now go practice explaining it to yourself using Crown and Coke as an example and it will all start making sense after about the third or fourth try. At least it did for me. :B

Good post!

The thing I like about HP is you can't "manufacture" it with gears. You want to make more torque to the tires? Just drop a gear. If you have an engine that makes 1000 ft/lbs of torque at the crank at a very low RPM if will not make a good TV engine because it can't do work in a timely fashion.

Now if you have an engine that makes 1000 HP at a high RPM it won't be fun to drive as a TV but with the right and enough gears it will fly up hills.

A good TV will have a good balance of both.

Double post

spoon059 wrote:

3 words... Jim Beam Vanilla...

You are welcome!

Hmmm, I might have to try that. Thanks!

ShinerBock wrote:
just like how happy I get depends on how much Crown is being applied to the Coke.

3 words... Jim Beam Vanilla...

You are welcome!

Torque and rpm combine to make horsepower just like Crown and Coke combine to make me happy.

How much horsepower is being made depends on how much torque is being applied at a certain rpm just like how happy I get depends on how much Crown is being applied to the Coke.

Torque without rotational movement is useless just like Coke without Crown is useless.

You see, you can't have one without the other.

Now go practice explaining it to yourself using Crown and Coke as an example and it will all start making sense after about the third or fourth try. At least it did for me. :B

4x4ord wrote:

travelnutz wrote:
As a nearly 40 year automotive engineer and automotive engineering operation owner, I sure as hell do know what I'm talking about! Taught many classes and you'd be wise to attend such! Torque and only torque is what and the force that turns the wheels to make the vehicle move at all or to any desired velocity and keeps it at that velocity also. Especially apparent on an uphill grade where torque does it all, all the time. Simple, as if you do NOT have adequate torque to maintain a desired velocity, the vehicle will drop in velocity.

Theoretical horsepower turns NO vehicle wheels nor does it apply one ounce of force to turn any wheel as horsepower is only theoretical calculation value. Torque is the only axle/wheel twisting force ever present! NO work is accomplished or done at all if there isn't adequate torque to make the wheels turn to any velocity. Try to deny this known well long time established FACT!!!

You've got your units confused. Asking how much torque is required to move a 20,000 lb truck up a 7% grade at 60 mph is like asking how may feet of gasoline it takes to fill your fuel tank.

Hp is a number used to tell you how much torque you need to produce at a rpm to achieve that speed. I think you guys are saying the same thing just have a different way of looking at the equation. How fast can you accelerate to 60mph up a 7% grade with 12.5k with 300hp? To answer the question you have to know how much torque you can apply through the RPM range. HP will just tell you the max speed it will achieve. If you don't have the ability to apply the torque needed to get the load to that max speed then max hp is useless.

Turtle n Peeps wrote:
So a 1000 ft/lb engine at 525 RPM will be towing beast? LOL

It would be if if it had a flat torque curve and maxed out at 3,000 rpm.

travelnutz wrote:
As a nearly 40 year automotive engineer and automotive engineering operation owner, I sure as hell do know what I'm talking about! Taught many classes and you'd be wise to attend such! Torque and only torque is what and the force that turns the wheels to make the vehicle move at all or to any desired velocity and keeps it at that velocity also. Especially apparent on an uphill grade where torque does it all, all the time. Simple, as if you do NOT have adequate torque to maintain a desired velocity, the vehicle will drop in velocity.

Theoretical horsepower turns NO vehicle wheels nor does it apply one ounce of force to turn any wheel as horsepower is only theoretical calculation value. Torque is the only axle/wheel twisting force ever present! NO work is accomplished or done at all if there isn't adequate torque to make the wheels turn to any velocity. Try to deny this known well long time established FACT!!!

You've got your units confused. Asking how much torque is required to move a 20,000 lb truck up a 7% grade at 60 mph is like asking how may feet of gasoline it takes to fill your fuel tank.

ShinerBock wrote:

Turtle n Peeps wrote:
So a 1000 ft/lb engine at 525 RPM will be towing beast? LOL

Man, that thing would fly up the Ike towing 12.5k lbs.......

Is what I would say if I were Amish.

well, in the extreme how about the sultzer 2 stroke marine engine. something over 5 million ft/lbs of torque at around 100 rpm.

oh, that translates to something over 100,000 hp

the most thermally efficient internal combustion engine in the world. very close to the theoretical thermal efficiency of a compression combustion engine.

now each piston weights 5 tons, and it uses 250tons of fuel/day at full power. each cylinder takes 6 ounces of fuel on each stroke at full power. displacement is 1800 litres per cylinder. 36inch bore, 8ft stroke.