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6.7 vs. 5.9

Old 01-05-2007, 06:34 PM
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6.7 vs. 5.9

So, I thought I'd be the 1st to post a question in this forum. Where are they getting the extra .8 liters from with the 6.7? Is it a different block, or did they just lengthen the stroke (and maybe enlarge the bore, too???) of the existing 5.9 that we all know and love? I appologize if someone has asked this before.

If it is the same block (or close to it), I wonder how long until someone puts 12v components onto one and sticks it into a 2nd gen.
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Old 01-05-2007, 06:43 PM
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i can see it now a p-pumped 6.7L cummins killing everyone at the pulls
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Old 01-05-2007, 08:18 PM
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They aren queezing it out of through the emisons control cram.
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Old 01-05-2007, 09:12 PM
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lgp9999:

You asked where Cummins is getting "the extra .8 liters from" on the new 6.7?

According to their press reports on the new 6.7, the cylinders have been bored out some going from 4.02 on the 5.9 to 4.21 on the 6.7. Cummins also increased the stroke, going from 4.72 on the 5.9 engine to 4.88 on the new 6.7 engine. This all results in a displacement increase from 359 cid. on the 5.9to 408 cid. on the new 6.7.

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Old 01-06-2007, 03:08 AM
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P-pumped 6.7, that's got a catchy sound to it. "I'm building a doomsday device and am going to aim it right up your hind knee!"
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Old 01-07-2007, 09:52 PM
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Originally Posted by rhino 660 View Post
i can see it now a p-pumped 6.7L cummins killing everyone at the pulls

If you look hard enough.. you'll find some out there bigger than 408... (In a 5.9L block.)
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Old 01-07-2007, 09:58 PM
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I wonder how much the fuel mileage is gonna drop over the 5.9? Makes you wonder why they went to the bigger engine. The 5.9 makes decent power so that isn't the reason for the step up.
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Old 01-07-2007, 10:28 PM
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Originally Posted by Mike Holmen View Post
I wonder how much the fuel mileage is gonna drop over the 5.9? Makes you wonder why they went to the bigger engine. The 5.9 makes decent power so that isn't the reason for the step up.

That's a good point especially considering how high fuel prices have been, anybody have an idea? What kinda mileage is the 6.7 supposed to get?
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Old 01-07-2007, 10:30 PM
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Originally Posted by Mike Holmen View Post
I wonder how much the fuel mileage is gonna drop over the 5.9? Makes you wonder why they went to the bigger engine. The 5.9 makes decent power so that isn't the reason for the step up.
Mike
The way I understand it is a larger displacement engine can put out the same amount of emissions as a smaller one and be labeled as cleaner?
Go figure, but I heard the 5.9 was having a hard time meeting the required emissions
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Old 01-07-2007, 11:03 PM
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the 6.7L engine doesnt have to work as hard to make the same amont of power as the smaller 5.9L. thus equals lower combustion temperatures and lowers the nox emissions, thats the only reason for the larger motor to get the nox ratings to meet EPA specs. As far as the particle emmisions thats where the DPF comes into play to catch the soot. Wes
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Old 01-08-2007, 01:03 AM
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Thanks to everyone who answered my questions.

Hmm, if I ever win the lottery I may build me a 12v 6.7.
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Old 01-08-2007, 01:34 PM
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According to their press reports on the new 6.7, the cylinders have been bored out some going from 4.02 on the 5.9 to 4.21 on the 6.7. Cummins also increased the stroke, going from 4.72 on the 5.9 engine to 4.88 on the new 6.7 engine. This all results in a displacement increase from 359 cid. on the 5.9to 408 cid. on the new 6.7.


4.21 X 4.21 X 4.88 X 6 X .7854 = 407.59247Ci


Last edited by John_P; 01-08-2007 at 05:52 PM. Reason: Poor choice of words toward another member.
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Old 01-08-2007, 03:24 PM
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steelblitzkrieg:

For your information, I took those numbers from Cummins own literature, so if it is wrong then I would say it is on the Cummins literature.

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Old 01-08-2007, 05:06 PM
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4.21 X 4.21 X 4.88 X 6 X .7854 = 407.59247Ci

[/quote]

Originally Posted by John_P

For your information, I took those numbers from Cummins own literature, so if it is wrong then I would say it is on the Cummins literature.
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John_P , I'm not pulling for either side here , but I think if you go back and read his post it is rather obvious that he is kidding , especially where he points out the 407.59247CID (which would be rounded up to 408 for any promotion and sales literature , as well as technical specifications and publications) as compared to your post stating 408CID. I'd say that you mis-interpreted his sense of humor, but that's JMO
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Old 01-08-2007, 05:16 PM
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John, Check your PM's I sent you a response.
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