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Ford Unveils New 6.7-L Power Stroke V-8 Turbocharged Diesel

Powerstroke
6.7-liter Power Stroke V-8 turbocharged diesel engine. Click to enlarge.

Ford has provided initial details on the new Ford-engineered, -tested and-manufactured 6.7-liter Power Stroke V-8 turbo diesel engine. Debuting in the next-generation F-Series Super Duty truck, the new diesel engine will deliver improvements in torque, horsepower and fuel economy while adding more fueling flexibility—the engine is sanctioned for up to B20 biodiesel blends—and meeting 2010 emissions requirements.

The diesel engine team made improvements and changes throughout the engine architecture—including the use of an “inboard exhaust” design, a first for a modern production diesel engine—to deliver on aggressive horsepower, torque, emissions and fuel economy targets.

Inboardexhaust
The inboard exhaust design reduces overall exhaust system volume. Reduced exhaust system surface area also minimizes heat transfer to the engine compartment and improves NVH. The turbocharger is center-mounted on a patented pedestal low in the back of the valley. Click to enlarge.

In January, Ford and Navistar, Ford’s long-time diesel supplier, agreed to end several years of litigation. Among the terms of the agreement was the end of the current diesel engine supply agreement effective 31 Dec 2009. The new Ford diesel steps fully into the opening.

All-new design. One of the obvious visual differences in the new 6.7-liter Power Stroke V-8 turbocharged diesel engine is the layout of the pipes. The exhaust manifolds, for example, reside in the valley of the engine instead of outboard, while the intake is outboard of the engine. The cylinder heads are essentially flipped around in comparison with previous V-8 engine architectures.

This layout has several advantages. First, the overall exhaust system volume is reduced, meaning air can be fed to the single turbocharger quicker for faster spool up and reduced lag, resulting in improved throttle response for the customer. The improved packaging also places components that need to be in cooler air away from hot exhaust pipes, resulting in better thermal management and, by extension, better fuel economy.

The physical size of the system is smaller, but more importantly, the air-handling part of the system is considerably smaller and that translates directly into the responsiveness of the engine.

—Adam Gryglak, Lead Engineering Manager

The volume of the exhaust system feeding the turbocharger is smaller by about 50% because of the inboard architecture.

Singleseq
The single-sequential turbo uses a double-sided compressor wheel mounted on a single shaft. It combines the benefits of a small turbocharger (faster response) and a large turbocharger (ability to compress and force more air into the engine for more power) in one unit. Click to enlarge.

Turbocharger. The single-sequential Honeywell turbocharger—an industry first—is key to the new diesel engine’s performance. The unit has two compressor wheels driven off one turbine impeller. This approach combines the benefits of a single inertia wheel—faster response without lag—with the thrust of a larger turbocharger, with the ability to force more compressed air into the engine for more power.

The engine’s smaller exhaust volume combined with a corresponding smaller intake volume and smaller turbocharger creates a system that is quicker to boost, more responsive and better able to deliver horsepower and torque, especially at the low end.

The turbocharger includes an advanced variable nozzle turbine, which enables variable vane pitch angles, driving optimal turbine power to achieve optimal boosting levels for all operating conditions. The single shaft ensures the transition is seamless. The compact unit is uniquely center-mounted on a patented pedestal low in the back of the valley instead of hung off the block, which helps balance the system and aids NVH characteristics.

Combustion system. To help reduce NOx emissions to required 2010 levels, the new Power Stroke reduces engine-out emissions. Ford’s system runs the engine with the least amount of oxygen possible in order to reduce NOx without degrading performance and fuel economy. Ford runs the exhaust gas recirculation (EGR) through a two-step process utilizing separate cooling sources. The end result is the EGR is brought into the intake at a lower temperature, which means more of it can be utilized, creating greater efficiency throughout the system.

Specific design upgrades were made to both the piston and the piston bowl to optimize the combustion process, which features a two-stage combustion event instead of a single-injection event, causing harsh, sudden and loud combustion.

The high-pressure Bosch fuel system injects fuel at up to 30,000 psi (2,000 bar) and can deliver up to five injection events per cylinder per cycle, while eight holes in the injector spray fuel into the bowl. The compressed-air ignition unique to diesels is aided by pilot fuel injections before the piston reaches the top, allowing the charge to heat up even hotter than what you get under normal compression.

Then when the main injection occurs, we can mitigate NVH because we have a slower ignition process. When the fuel burns, it doesn't burn with a traditional pop or bang. The direct-injection system is calibrated and phased for optimum power, fuel efficiency and NVH.

—Adam Gryglak

The new 6.7-liter Power Stroke V-8 turbocharged engine features instant-start glow plugs, allowing quick start even in extremely cold temperatures.

Emissions. The new 6.7-liter Power Stroke V-8 turbocharged diesel will employ an aftertreatment system to help comply with 2010 federal regulations to reduce nitrogen-oxide levels in diesel emissions by more than 80% compared with the previous standard. The Ford aftertreatment system is a three-stage process.

  • The first step in cleaning the diesel exhaust occurs when the exhaust stream enters the Diesel Oxidation Catalyst (DOC). The role of the DOC is twofold. First, it converts and oxidizes hydrocarbons into water and carbon dioxide. This conversion happens at about 250 °C. Second, the DOC is used to provide and promote heat, using specific engine management strategies, into the exhaust system. Through appropriate thermal management, this heat increases the conversion efficiency of the downstream subsystem(s) in reducing emissions.

  • Urea SCR. Before the exhaust gas enters the SCR chamber, it is dosed with DEF, an aqueous solution that is approximately 67.5% water and 32.5% pure urea. Dosing occurs between 200 and 500 °C.

  • Diesel Particulate Filter (DPF). Periodic regeneration occurs at temperatures in excess of 600 °C.

Block. The new Power Stroke’s block is made from compacted graphite iron (CGI), which is about twice as strong as regular gray cast iron. While this is the first use of a CGI block in North America in this class of vehicle, Ford has successfully used the material in engine blocks in other products around the world.

The diesel engine’s deep-skirted block and main bearing caps are cross-bolted for additional stiffness and to aid NVH. The cylinder heads mirror the engine’s attributes as a whole, with lighter weight combined with increased robustness: The cylinder heads are made of aluminum to save weight and, for improved sealing, feature six head bolts per cylinder versus the four head bolts found on other engines.

The cylinder heads, which feature dual water jackets, are capable of firing pressures approaching 2,600 psi. The tall water jacket works as a manifold, flowing high-velocity water for cooling and adding to the structural robustness in the head to handle the higher firing pressures. Crankshaft durability is improved through Ford’s unique undercut and fillet roll treatment to relieve stress.

The valvetrain features patented dual hydraulic lash adjustors, which improves the performance and reliability of the valvetrain by using two pushrods per cylinder instead of the conventional single pushrod, with individual rocker arms. Other proven components round out the engine hardware, including fractured-split connecting rods and a fuel system capable of generating 30,000 psi to feed the common-rail direct-injection fuel system.

The oil pan, which bolts to the transmission, also acts as a structural member for improved powertrain stiffness.

Comments

joookes

Target specs:
390 hp
700 lb-ft

This sucker had better be reliable.

JN2

Joookes, BMW's 123d gets 204hp, 295lb-ft from 2.0 liters. At Ford's 6.7 liters that would be 683hp, 988 lb-ft. I don't think the Ford is stressed.

jason.thompson

Differences
6 head bolts per cylinder versus 6.4L & 6.0L 4 bolts.
Air to water intercooler versus air to air.
Hot side EGR valve versus cold side EGR valve.
Two separate cooling systems 194F and 122F.

http://www.dieselpowermag.com/features/ford/0910dp_ford_6_7l_powerstroke_diesel_engine/index.html

Stan Peterson

The new small Cummmins v8 and v6 turbo-diesels, also uses the same valley mounted exhaust turbo. The benefits for rapid warming of the catalytic converters plus the ease of re-routing EGRhe design just lends itelf to the modern world, where diesels need to be much cleaner.

Will S

Another exercise in building monuments to overconsumption. Hopefully, this is targeted to heavy work vehicles, not people who want to race each other while towing their boats...

Bernard

It may not seem stressed compared to a compact car application, but this engine should spend more of its service life at or near its maximum power output. Max power and torque figures for passenger cars are mostly anecdotal, since they only get used for a few seconds at a time. If you can do 0-60 in under 8 seconds, how long can you really hold max power for?

Will S, think of this as the truck they use to deliver solar panels to your house. It serves a definite purpose, and it's way more economical than a 5 ton truck (or the 10 Priuses you would need to tow the same load).

Will S

I hear you, Bernard, but given my druthers, I'd preferred my solar panels delivered by the following;
http://www.greencarcongress.com/2009/08/cargohopper-20090828.html#more

It won't serve every local haul purpose, but could make a significant dent in areas where steep hills aren't an issue.

My solar panels were delivered 10 years ago, btw...

joookes

As I recall, some F-550s are being converted to PHEV, not sure on Ford's level of involvement. An F-550 pure EV is a long, long ways out but PHEV could be closer than we think.

This new engine has a standardized bolt pattern, so conceivably something off the shelf like an Eaton parallel hybrid system using the 6-spd automated manual transmission could work.

The energy storage alone could make is worthwhile for some, to run tools, whereas others would find the city MPGs pay-off. I have my doubts as to whether PHEV Class 4/5 trucks will ever fill out beyond commercial niches and rich ranchers with renewable energy on-site, etc.

The Goracle

.

Awesome! My 1.6 liter diesel only cranks out 52 Hp. As worn out as it is that 52 Hp is probably down to 39 Hp.

Praise be to Algore.

.

fred

So how hard could it be to make a 3.35L(or even less)??V8s and V8 diesels are a nightmare.

jerktaculus

I wish people would publish brake mean specific fuel consumption information or load vs rpm with fuel consumption data - for all the talk about metrics like max hp and torque - one needs to know how useable the entire engine operational envelope is .. particularly how wide the most efficient operating points are -

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