Although not releasing new torque and horsepower numbers, Ford is making significant improvements to its 6.7-liter Power Stroke engine for 2015 model year Super Duty trucks.

In making the announcement today at the Texas State Fair, Ford said the second-generation Power Stroke will benefit from a larger Garrett GT37 turbocharger, replacing the GT32. The GT37 features a single, larger 88-millimeter compressor wheel that replaces the GT32’s dual-sided compressor design. The turbine size is increased to 72.5 millimeters from 64 millimeters, so exhaust gases have a larger surface area to spin the turbo. The wastegate and the wastegate controls are also eliminated, because the turbo operates at lower peak pressures than the GT32.

“The original designers of the current Power Stroke V8 diesel forecasted needs for higher output. This facilitated the larger turbocharger, increasing airflow and creating more power,” says David Ives, Power Stroke technical specialist. “We’ve dramatically improved performance while reducing overall engine complexity by focusing on the turbo system.”

Ford notes that another benefit of the larger turbo is improved engine exhaust braking, which is manually controlled by a push-button switch on the dashboard. The new turbo is also driving improvements to the fuel delivery system, specifically a new high-pressure fuel pump and fuel injectors. The pump’s cam stroke is increased to deliver more fuel, and the injector’s tips are designed to better atomize the fuel. On the exhaust side, Ford is adding a new temperature sensor to help with fuel control. Other changes to the 2015 Super Duty include:

• New torque converter to manage increased horsepower and torque
• New polymer coating on main bearings
• Improved crankshaft fillet design – the transition point between the crankshaft’s journals – to increase crankshaft power-carrying capability
• Increased crankshaft damper weight to reduce rotating forces on the crankshaft
• New five-layer head gasket
• Added material to cylinder heads, exhaust manifold, and valvetrain
• Redesigned turbo oil and cooling lines to improve sealing
• Piston assembly upgrades to increase load-bearing capability
• New 4-layer exhaust manifold gasket for improved durability

Again, Ford didn’t release revised horsepower and torque numbers. That announcement probably won’t come until just before the vehicles go into production. Today’s teasing is likely a counter to GM’s unveiling of its redesigned 2015 heavy-duty pickups, also at the Texas State Fair. The current Power Stroke is rated at 400 horsepower — which leads the category — and 800 lb-ft peak torque, which trails the 850 lb-ft number offered by Ram with the Cummins turbodiesel.