Those of you who have now had both or driven one of each, which engine do you feel is more powerful stock with a load. Also which do you feel is more efficient? I am looking to replace my current truck soon and am looking for opinions.
Thanks in advace.

Jason

 

More efficient=5.9L (view all the posts on 6.7 milage), also will be in the shop less=5.9 more efficient
More powerful= Probably the 6.7L, only if you have a 6spd auto, because of the auto and keeping you in the torque curve better w/6 gears. I would not own a 6.7 if I had the option, all I can recommend is drive both for yourself. I was very disappointed in every 6.7L I have driven, why couldn't DC have mated the 5.9L w/ a 6 spd auto, would have been the perfect truck for us auto lovers! Also MAKE SURE TO Pop the hood on both trucks, which one looks like less to go wrong. Murphy's law!

 

Thanks for the reply tcr. Makes good sense.

 

Been a guinea pig too many times in the past - didn't want to take the chance, so I got an 07 5.9.

And I don't trust automatic tranny's in big diesels, so it was a no-brainer for me.

 

I agree. I will not ever own another auto in a diesel to work with. I tried one and I was screwed so bad by my loving dealership.

 

My mileage has been about the same with the 6.7 as it has when my buddy's 07 5.9 was breaking in.

 

My 6.7 w/G56 WILL beat any stock 5.9 with a load! I've tested it several times!

 

I was in your shoes, and there were a few things that steered me towards the 5.9:
- Proven track record
- Fuel compatibility (6.7's and bio? supposedly not compatible)
- Simplicity
- Tunability
- Less $$$

Also- the new 6.7's come with an unproven engine/accessories/exhaust as well as an unproven new transmission (I would guess rebuilding a 6spd auto would be a lot more expensive than rebuilding a 4spd auto...). If you got a 6.7 with a manual trans, at least there would only be one variable...

LOVE MY NEW 5.9!!!

 

The answer to your question is the EPA. Because of all of their crap the EPA made them add to the engine Cummins felt the 5.9 would not meet the new smog crap requirements mandated by the EPA nor could it keep up with the newer Ford or GMC 350 HP, 650 TQ engines they were making for their 2007.5/2008 trucks so they made the new 6.7L.

 

Well, the 68RFE is unproven I'll grant you that. But the Aisin is only new to Dodge. It has been around for awhile and, like the CTD, is a medium duty rated tranny. I would have NO hesitation with that one!

 

Ask the same question in two years. I tip my hat to the folks getting the new ultra low emission diesels because they are nothing more than guinea pigs for those that are in the "wait and see" mode.

I have no doubt that in time the bugs and quirks will be worked out with the new fangled low emission engines, but until then now way in hades will I own one.

I really like the idea of a 6 speed auto, but I ain't that inclined to abandon the tried and true 5.9 workhorse. Maybe 4-5 years down the road the 6.7 will be as tried and true as the 5.9, at least I sure hope so. With a Cummins under the hood I have faith.

 

What a bunch of naysayers!
My 2004.5 5.9 had me walking 5 times. 4 injectors and 1 lift pump in 30,000 miles. Yep i had a quad 60hp box on it and yep DCX paid the bill because I could prove the box did not increase pressure only duration, now mix in ULSD and lack of lubricity and it was a "no brainer" to go with the 6.7 and the 68rfe
2000 miles with 3/4 of that city (5 or 6 miles) overhead reads 11.5 which is 10.4 real, towing 13,500 overhead reads 10.7 real 9.9 running 75mph easy and it does not hunt like the 48rfe on hills. The ebrake is to die for and the tranny gears are made like they pulled a trailer before the set the gear set. Instead of wanting to add chips and dips I added a quad commander just to so I can monitor all the important stuff and it's like this truck takes care of it's self. I did not want to by a 2007.5 but wanted to wait for the 08's, would I do it again? In a heart beat.
Fred

 

I just traded in an 06 5.9 w/48rfe for an 07 6.7, 68rfe, The 6.7 for first two days, definately stronger. 68rfe, worth a million compared to the 48 series. So far, 15.4 mpg showing on monitor and this is with 4:10 posi's. Very happy with it so far.

 

Glad to hear a lot of people are liking their 6.7's. It's not a Powerjoke! (hmmm need to remove the valve cover on my 6.4, better lift the cab first... OH, looks like that's the ONLY WAY)

 

so far it is doing quite well...it hauls a load without flinching. As far as biodiesel is concerned they actually were shipped in many cases from the factory with B5 in them. They run perfectly fine on bio. Cummins isnt concerned if you check their website all their diesels run bio.