Ok, it took me a bit but here's some addition information to clarify some of those questions regarding the 6.7L engine design, oil change intervals, etc. Yes, some of it reads like techno-babble, but I tried to keep it reasonable.

Beginning with utilizing CGI as the block material for the 6.7L vs. gray iron for previous generation engines, CGI has nearly 2x the strength. This material choice allows thinner castings, reduces engine weight all while providing the foundation for the overall engine design that is stronger than previous designs. Weight is crucial for this class of trucks as it allows for additional improvements in fuel economy, but more importantly, it improves front GAWR (gross axle weight rating) for such things snow plow applications and overall vehicle loading needs.

CGI also has a higher "stiffness" than that of gray iron. Improved stiffness of the block, coupled with the structural oil pan allowing use of the SAE 2 standard for transmission coupling vastly improves powertrain bending. Powertrain bending or low frequency first order nodal response is nothing more than the transmission of NVH inputs of the powertrain (engine & transmission) to the driver measured in frequency (Hz) and velocity (mm/sec). From a customer's perspective however, managing powertrain bending drives one of the fundamental basics of the vehicle being quiet, sounds tight and feels right, etc. Other inputs are things like tire noise, driveline balance (tires, wheels, driveshafts, etc.).

The design of the block incorporates the deep skirt, 6-bolt per bulkhead bottom end. This feature reduces the number of joints relative to a bedplate, so is more robust against oil leaks, while also providing a stronger, stiffer bottom end. The added strength and cross bolts stiffness improves NVH as well. By having separate main caps, we are able to use stronger nodular iron caps for the heaviest loaded part of the bottom end, without sacrificing machine-ability of the remainder of the lower portion of the block.

Oil consumption, washing of cylinder bores (fuel past the ring) are all predicated on the bore being symmetrical, proper piston fit, and ultimately the ring pack that's used. If you have good control over these inputs the result is much less oil being burned, much less fuel entering the sump, fewer DPF regeneration events as ash isn't being developed during the combustion event.

Fuel control is also critical, number of nozzle holes in the injector for atomization, injection timing and multiple injection event capability (three to five events between pre and post TDC) provide very finite control capability.

From a sump capacity perspective let's just say that there is such a thing as overkill. When you look at the industry as a whole from a "cost of ownership" perspective, which btw is one of my job functions, Ford was out of bed. The migration from a 3K mile oil change to 5K to 7.5K and now finally 10K has been a very frustrating experience. Not so much that the capability wasn't there, it's that engineers are, well, way over-protective at times. When you look at the cost impact to the customer associated with improving overall maintenance requirements, it's a pretty big deal. At one point we were at twice the cost of our primary competitor for 5yr 100K maintenance for oil, oil filter, fuel filters(s) and air filters. If you’re a fleet owner, some of which have many hundreds of these trucks on the road, you have to be sensitive to this. If you want to see how crazy this is getting, checkout what's happening in Europe from a cost of ownership perspective. OEM's are competing at selling a vehicle based on the maintenance interval of 1 (Once) every two years! or 30K Km. (insane)

There were two primary contributors with the first being engine oil sump capacity was almost 50% higher in one case and roughly 30% more in another. It didn't take rocket science to figure out that if your competitors are doing it, then you probably should take a harder look at what you're doing. The second contributor was fuel filtration as Ford has for quite some time run a two filter or dual stage strategy for fuel. With the changes made on 6.7L, even with post injection, we are now either equal or better when measuring the impact of cost of ownership for general maintenance. Note that the emissions standards increase forcing after-treatment complexity. Achieving the LEV II emissions standards through the adoption of ultra low sulphur fuels and low ash engine oils drove significant changes in engine hardware and calibration.

Management of the oil system is always a top priority. As I mentioned in my other response, during engine development it was determined that DSI (down stream injection or 9th injector) was less desirable for a number of factors for this engine program. Refinement of the active/passive regeneration strategy, eliminating the complexity of having another low pressure fuel system to manage, improved engine efficiency and the cost were just a few of the variables. The oil life monitor/systems programming is designed such that it monitors the engines operating parameters (temp, speed, engine load, frequency of dpf regen events, etc.) and adjusts oil change intervals accordingly. During engine development, sump oil levels were monitored through instrumentation of the sump itself to correlate the data.

Hope this helps!

Best Regards,

-Paul











Disclaimer: I work for Ford, this is my opinion and not that of Ford Motor Company.<O></O>

 

Paul,

Thanks for the additional insights. As an engineer with 15+ years in the diesel construction equipment business, I found the design of the 6.7 to be eloquent. The trade-offs that your team worked though and ultimately resolved were challenging and I think with time will prove brillant. I have ordered (waiting now) this truck primarily becuase it is the class leader in all ways, but also as a reward to Ford for outstanding R&D. I use my $$ to recognize outstanding design. The 6.7 might not prove as timeless a design as a John Browning 1911, but I suspect you and your team have raised the bar against the competition and will influence diesel engine designs for years to come. Kudos to all.

Keep the tech updates and insights coming. Just more fuel for the fire!

 

hey redneck trucker im new to this and need some tips can you help me out

 

I almost understood all of it. Keep up the info. Makes for great discussion ammo.

 

I love the new engine. It runs rings around my old 6.4. Just wish they went with iron heads. The aluminum ones seem to have been holding up ok in the Dmax though for the past 10 yrs.

 

I used to think the same way. But a well enginered aluminum head has got to be stronger, lighter and have better heat transfer than an iron head. And these new diesels run a lot hotter than the old ones.
I've heard very few people complain about D-Max heads.

 

Paul,

It's great to understand the reasoning for Ford sticking with exhaust-stroke injection for dpf cleaning. It seems that the only negative is the potential for oil dilution due to fuel contamination.

Is there any data on what type of driving creates the best and worst case scenario for oil growth? Heavy towing vs. grocery-getting use? Also, is there a maximum acceptable fuel content threshold in an oil analysis? In other words, should the oil be changed if the fuel content is greater than 5% or 10%? What is the maximum safe level where the oil is still able to do its job?

 

I currently have 8500 miles on my oil and it's killing me! I keep waiting for the oil change light to come on! I am happy though, besides saving me around $300/month in reduced fuel cost, this '11 6.7 appears to also be saving me $100/6 weeks by having longer oil change intervals.

The engineering is paying off, cost of ownership is lower on these 6.7's and we all benefit! I have 13,400 miles so far and very happy with the engine and the 6 speed transmission.

 

It's become negligible for the most part. 7% fuel in oil is the number that used fairly consistently as to when to start to get nervous. Worst case duty cycle is max gvw, low speed operation, urban city driving. Keep in mind that you'd need to run above that percentage for extended periods of time to have any significant affect and the intelligent oil minder system would make you aware that an oil change is required long before that. Early on during engine development, we had targeted a 15K oil change interval. Test data showed we could get there for all but the most severe conditions and even that was borderline to being acceptable.

-Paul


"It seems that the only negative is the potential for oil dilution due to fuel contamination."

 

Now that was an interesting piece of information...sort of makes me not worry a bit about fuel dilution. I was not too concerned to begin with but there are some that have tried to make an issue out of it.

Thanks Paul, keep it coming

Regards

 

I know! Can you imagine our group trying to answer that question? As well intended as we all might be, we just don't have the data to have any level of credibility. I asked the question and within hours Paul comes back with a perspective that includes millions of dollars worth of engineering and real-world experience.

I asked the question because I got my oil analysis back from Blackstone which showed everything as a normal break-in engine should. The only item that gave me any concern was the fuel content was just under 4%. Without Paul's comment, I have no reference to know whether that is good or bad. I am also glad to know that I am a severe service user based on my mostly urban/grocery-getting driving style. This gives me the proper information I needed.

Thanks Paul.

 

Fantastic post. This really shows their passion for being the best and their connection with the consumers. Great info!

 

Thanks for the insight Paul. Congratulations to your team for creating the 6.7. I'm not ready for a new truck yet but wouldn't have any reservations about one of these.

 

Bump. I wish I had read this earlier in my 6.7 owning career. Thanks Paul.

 

Paul,

From a former Ford owner (Ford Tempo AWD -- won't say more...) and a soon to be Ford owner again (F350), thank you for taking the time to explain the technology and Ford's strategy.

I happen to be one of those people in a unique position. I have been driving a new Ford every year for the past 23 years and haven't owned one since my wife's 1989 Ford Tempo. As a fleet driver (company cars), I have seen a steady increase in Ford's attention to cost of ownership and stronger willingness to address issues that impact fleet operations -- not just from the perspective of the cost of the fleet maintenance but more importantly recognizing it costs your customers real money (i.e. taking a revenue generating employee out of the field to tend to their assigned company car maintenance issue).

I have seen such an improvement, that not only did I consciously make a decision to once again buy a Ford, I elected to buy a vehicle with a first year engine and transmission. Something that has been one of my golden rules "Thou shalt not buy the first model year of a new design".

With the availablity of forums like this, quality issues boil quickly to the surface. And it was the lack of serious issues that made my decision easier to buy.

Thanks again for the information and I hope your AFR (annual failure rate) is decidedly in your favor!