6.7 Cummins vs 6.6 Duramax

Most trains and certain ships use V configurations to fit in tight spaces versus a longer I configuration. Most big ships where a compact space is not an issue and efficiency is more important, an inline engine is used.

The physics lesson has been fun.
Out of the three of them, I still like my Ram the best. I say get the pretty one. The thing I’m not too crazy about is the dark blue exterior and dark gray interior. They initially look great but are hard to keep clean. We always try avoid any sentence or thought that includes the word dirt. We do like the
4x4 feature except for the fact that I have to have a ladder to wash it (but the ladder allows a longer stroke while I’m still the same displacement).
Happy shopping, I’m jealous!

Grit dog wrote:
I'm guessing Soonerwing03 couldn't give 2 schitts about all this....
Maybe we could get back to complaining about why he has a lift kit on his current rig, then he could participate in the fun!

LMAO

Probably because I am compensating for having a small sinep. Lol

Bought the Tahoe in June of 17. Went camping to CO over Labor Day weekend 17’ and Memorial Day weekend 18’ sleeping in a tent. Wife said no more freezing her butt off so we bought the TT in July 18’. Economics of trading in the Tahoe weren’t too appealing at the time and still aren’t which is why I am considering hanging onto it and passing it down through the 3 boys as each of their first car. Downside to that is that their second vehicle is going to suck compared to their first I guess. Well maybe not the baby, it may be in rough shape 6.5 years from now and two 16 year old's later.

Pulls like a train.

You all do realize most modern trains have V16 diesel engines. As are many of the current cruise ship diesel engines are V models.

Boy step on the Cummins by stating long stroke engines have higher piston speeds and all h$ll breaks loose.

I'm guessing Soonerwing03 couldn't give 2 schitts about all this....
Maybe we could get back to complaining about why he has a lift kit on his current rig, then he could participate in the fun!

ShinerBock wrote:

4x4ord wrote:

This bit about natuaral torque coming from a longer stroke is bs. If the displacement remains the same that longer stroke is going to dictate a smaller bore. Torque is a reflection of the amount of heat energy released from the fuel during a power stroke. So it is a function of cylinder volume and volumetric efficiency.



Edit: besides the above the Powerstroke has a longer stroke than the Cummins...... does this mean the Powerstroke pulls like a freight train compared to a Cummins.:)

Torque = force x distance. Longer stroke = longer distance. If two engines are generating the same force to the top of that piston, but one has longer rod turning the crank, then it will have more torque.

Also, the 4.88 inch stroke of the Cummins is much longer than the 4.25 inches of the Powerstroke, and both are longer than the 4.06 inches of the Duramax.

Correction, the Duramax has a 3.89 inch stroke, not a 4.06 inch stroke.

ShinerBock wrote:

4x4ord wrote:

This bit about natuaral torque coming from a longer stroke is bs. If the displacement remains the same that longer stroke is going to dictate a smaller bore. Torque is a reflection of the amount of heat energy released from the fuel during a power stroke. So it is a function of cylinder volume and volumetric efficiency.



Edit: besides the above the Powerstroke has a longer stroke than the Cummins...... does this mean the Powerstroke pulls like a freight train compared to a Cummins.:)

Torque = force x distance. Longer stroke = longer distance. If two engines are generating the same force to the top of that piston, but one has longer rod turning the crank, then it will have more torque.

Also, the 4.88 inch stroke of the Cummins is much longer than the 4.25 inches of the Powerstroke, and both are longer than the 4.06 inches of the Duramax.

You're right the Cummins has a longer stroke than the Powerstroke ... that was my bad. But stroke length makes no difference to torque if you keep the same displacement. Think of the pressure on the top of the piston in psi. A smaller piston with a longer stroke and or less pistons with a longer stroke means less force on that longer lever. If you think about it you'll come to realize that overall displacement and volumetric efficiency determine the amount of fuel that can be utilized per revolution which determines the torque output of an engine.

wnjj wrote:
Well in 2017 at least it would appear that the Duramax managed to out-freight train the Cummins:
https://images.app.goo.gl/FdYZ41ETQaEqeZLQ9

When an engine achieves peak on a wheel end dyno is not accurate. A lot of things come into play like how the torque converter locks up and at what gear. Then there is torque management which makes it even harder to depending on the vehicle. Trying to get it just right on certain dynos is down right tricky from one vehicles tot he next.

Wheel end dynos are also done at wide open throttle and the "pull like a train" people are referring to is at low rpm part throttle(normal driving) when the turbo does not come into play as much.

Well in 2017 at least it would appear that the Duramax managed to out-freight train the Cummins:
https://images.app.goo.gl/FdYZ41ETQaEqeZLQ9

4x4ord wrote:

This bit about natuaral torque coming from a longer stroke is bs. If the displacement remains the same that longer stroke is going to dictate a smaller bore. Torque is a reflection of the amount of heat energy released from the fuel during a power stroke. So it is a function of cylinder volume and volumetric efficiency.



Edit: besides the above the Powerstroke has a longer stroke than the Cummins...... does this mean the Powerstroke pulls like a freight train compared to a Cummins.:)

Torque = force x distance. Longer stroke = longer distance. If two engines are generating the same force to the top of that piston, but one has longer rod turning the crank, then it will have more torque.

Also, the 4.88 inch stroke of the Cummins is much longer than the 4.25 inches of the Powerstroke, and both are longer than the 4.06 inches of the Duramax.