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Ford 6.7L Powerstroke Diesel Engine - Code Name: Scorpion

Ford's New 6.7L Power Stroke

Photography by Courtesy of Ford Motor Company

You're looking at Ford's all-new 6.7L Power Stroke engine (code named Scorpion) that will debut in the 2011 Super Duty, due out in the first quarter of 2010. New engine programs like this don't happen very often, so Ford invited us into its Beech Daly Tech Center in Dearborn, Michigan, to give Diesel Power readers the first look at the next Power Stroke.

What Happened To International?
Ford says in order to stay competitive and profitable in the diesel segment, it needed to develop its own in-house diesel engine program. Ford and International have worked together for more than 30 years and have sold more than 3 million Power Stroke engines in Ford trucks. Ford and International will continue to do business together in the medium-duty truck market as partners in the Blue Diamond joint venture, as well as in other markets outside of North America.

Ford's First Diesel
Ford has been working on single-cylinder diesel engines in its labs since 2001 and has built diesel engines in Europe for years. Ford partnered with the Austrian engineering firm AVL to conceptualize the 6.7L Power Stroke's design back in 2006. The first prototype engines were running by 2007. While most engine programs take 36 to 48 months, the new Power Stoke was said to be completed in 24 months. When it goes into production, the new engine will be built in Chihuahua, Mexico.

Short-Block
The 6.7L engine block is cast from compacted graphite iron-a first in this segment-by Tupy for reduced weight and increased strength. Tupy also does the initial machining of the casting, called super cubing, before shipping them to Ford. The block has a deep-skirt design that eliminates the bedplate used on the 6.0L and 6.4L Power Stroke. The cross-bolted main bearing caps are made of nodular iron and hold the forged steel crankshaft in place with six bolts each.

Mahle builds the forged connecting rods with cracked caps, but they are not powdered metal as we had expected. The rods have their large bearing journals clocked slightly (like the Cummins) in order to fit the big end in the deep-skirt block. The cast-aluminum pistons are made by Federal Mogul and use offset pins and a single oil galley for cooling. The compression ratio is 16.2:1, making it lower than either the 6.6L Duramax, or 6.7L Cummins engines. The oil pan holds 13 quarts of 15w-40 conventional oil, which is two quarts less than the older Power Strokes. The 6.7L is said to be 160 pounds lighter than the current 6.4L, meaning the engine will weigh more than the Duramax, but less than the Cummins.

Cooling System
There are two separate cooling systems on the engine: a high-temperature system that runs at 194 degrees to cool the engine, as well as a low-temperature system that cools an air-to-water intercooler, transmission fluid, fuel cooler, and EGR system with a 122-degree coolant. A belt-driven pump mounted low on the driver side circulates the high-temperature coolant, while a separate belt-driven pump mounted higher on the passenger side circulates the low-temperature coolant.

Cylinder Heads
The reverse-flow aluminum cylinder heads breathe in air from the outside (where the exhaust manifolds would typically be on a V-8) and the exhaust flows out into the lifter valley (where the intake manifold would traditionally be). The 32-valve cylinder heads feature four rocker arms and pushrods per cylinder. The roller lifters ride on a single camshaft (located in the block) and have an oval shape so they can actuate two pushrods each. This system is said to reduce rocker arm pivot wear and make the engine quieter than the rocker bridge design used on the 6.4L Power Stroke, Duramax, and Cummins engines

Turbocharger
The 6.7L uses a Garrett single sequential turbo (SST) with variable geometry, a dual-scroll exhaust housing, and an externally actuated wastegate. This turbo has a pair of compressor wheels that are coupled together on a single shaft driven by the turbine wheel. The design is said to dramatically increase the compressor map's range and functions like a sequential twin-turbo system. The boost pressure will be around 30 psi, the turbine shaft speed will see up to 130,000 rpm, and the whole system was designed to function as an exhaust brake. The compressed air will be cooled by an air-to-water intercooler-another first in this segment.

Injection System
The 30,000-psi third-generation Bosch common-rail piezo injection system uses a Bosch CP4.2 pump and piezo electric injectors. Each injector has eight holes and is capable of up to five injection events per combustion cycle. The system does not use cylinder pressure sensors, but the engine was designed to be able to package them in the future. Ford will allow customers to run B20 (20 percent biodiesel) and has conducted 250,000 miles of durability testing to confirm the engine can handle it.

Emissions System
The Scorpion's EGR system feeds exhaust from the passenger-side manifold at 1,472 degrees to a new, hot-side Pierburg EGR valve. This means the control of EGR flow is done before the EGR goes through the cooler-no other diesel in a pickup does this-in order to prevent EGR sludge buildup in the valve and engine.

The EGR valve housing is cooled and will be made of aluminum on F-250 and F-350 applications and cast iron on F-450 and F-550 applications. The EGR system uses two floating core coolers that can expand and contract to reduce the chance of failure. The EGR system also has a bypass feature that skips the cooler in order to get the engine to warm up quicker.

When the exhaust leaves the engine, it flows through a diesel oxidation catalyst, then into the selective catalyst reduction device (where urea is injected to reduce NOx), and finally through a small diesel particulate filter. The urea system was deigned by Bosch and should allow 7,500 miles between fill-ups.

Noise
Three years ago, Ford spent $300,000 upgrading its noise, vibration, and harmonics (NVH) facilities to test diesel engines. We were able to stand in an NVH dyno cell and listen to the 6.7L engine run. In order to show us what a difference Ford's pilot injection calibration makes, the engineers toggled the pilot injection on and off. With the system off, the 6.7L sounded like the first '94 1/2 7.3L Power Stroke, but with the pilot injection turned on, it seemed much quieter than the current Duramax or Cummins. The Scorpion sounds quite impressive.

Fuel Economy
No figures were quoted, but we were told the new 6.7L will offer a substantial fuel economy increase over the 6.4L. The smaller DPF on the 6.7L would indicate the new engine will use less fuel-economy-killing active regeneration.

Power Output
Again, no power figures were quoted, but we were told peak horsepower will be made at 2,800 rpm and the torque peak will be at 1,600 rpm. We expect the engine is capable of more than 400 hp and 750 lb-ft but suspect the power ratings will debut at approximately 380 hp and 700 lb-ft.

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