I posted this here in general diesel discussion, if it belongs in off-topic please feel free to move it.
I have been reading up on the cummins B-series engine, specifically the inline six, 5.9 and 6.7L motors and i'm wondering how are they wringing so much power out of these inline motors?
Inline engines, especially when you get to 6+ cylinders are known for their imbalance and other properties which lead manufacturers to leave them behind many decades ago.
How is it that cummins has gotten so much power out of this mill?
The further refinements of the engine have added to power increasingly at rates of nearly double their competitors...this is not an apples to apples comparison but GM's ls based 5.3L engine went thru a few revisions each time gaining around 8-10HP mean while cummins revisions yield 20-30HP increases.
Just curious as there is a bunch of information regarding the details of the engines themselves but not the underlying engine building concepts that have lead to this engine continually beating its competitors in power output with less cylinders and "outdated cylinder configurations" (if you will)....
It's like tying your leg behind your back and running a race against pro's and still winning...
If the inline 6 motors were really that imbalanced and terrible from the start, the class 8 trucks wouldn't be running them... Every 18wheeler on the road has an inline 6 motor. A whole lot of them have more than a million miles without ever having opened the motor up. The reason they are still used is because they are reliable, fewer moving parts and they are torque factories.
My work truck for example, a 2013 Freighliner Cascadia Daycab. 600HP and over 2000 FT LBS of torque. And yes it has a Cummins engine. I may not like Chrysler products, but the Cummins motors are some nice powerplants.
This matches my thoughts. Tractors of all brands run inline motors 3,4, and 6 and they have a high torque to horse ratio.
And what about the old DT360 and DT466. They are older engines but can hold up to 1000 horses without being filled and a girdle ect.
Plus inlines (mechanically fuel injected) are easy to get horsepower out of verses a v8, less rotating mass, ect. So to me that says they are actually better powerplants. Just my opinion though.
Ive always dreamed of an inline six for the superduties. Where you actually have room under the hood to do maint and repair without having to lift the cab.
Rates nearly double their competitors? Um the 2017 SD with a 6.7 V8 is rated 440/900 and dodges 6.7 Cummins is rated 385/900? Also GM just released duramax numbers to be 445/910.
The 2017 Ford's numbers are 440/925. The GM has the transmission to support those numbers with the Allison behind it, whereas Dodge, to compete, is going to be in a world of hurt with their transmissions if they try to get back into the numbers race. I have a friend who is big into the Cummins engines who tells me that they are having some major tranny problems. Even with the Aisen. He tells me that they (the Aisen) aren't very good, but better than the 68RFE. He said the 68rfe is using the same technology that Dodge has been using since the 1960's. He's discouraged, but loves his old Cummins.
Looks like we won't be hearing Sam Elliot in his deep voice saying "Best in Class Torque" on those TV commercials for a while. Maybe GM and Ford should hire him.
I don't think it has a lot to do with balance.
Any engine can be balanced, doesn't necessarily mean it'll make more power.
Every one I've been around has had more in cab "vibration."
The main reason they make so much HP, is the 6BT platform base has been around since 1950. That being said, that is that many more years that people have been playing around with R&D. When I worked at the steelmill, a friend of mine brought in a diesel engine repair manual that was from the late 50's as his dad was a diesel mechanic. One of the old hardback books with cloth covering. It was pretty cool to flip through the pages and when I seen what looked exactly like a 6bt I went right to the copyright year of the book. LOL.
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