Towing and cooling requirements forced Cadillac to modify the Blackwing engine substantially for this application.
Though it may not be a Blackwing, the Cadillac Escalade V shares a lot of its engine architecture with the Blackwing-badged CT5-V sedan. Just how much has Cadillac changed to get the engine to work in its full-size SUV? We spoke with one of the Escalade V’s lead engineers to find out.
“The engine [block] itself is the CT5-V Blackwing engine,” Charlie Allen, engine design system manager for the Escalade V, told Road & Track. “So that’s our LT4 engine that goes back to the C7 Z06.”
In addition to the block, the forged crankshaft, forged connecting rods, forged pistons, and lightweight titanium intake valves are also shared with the Blackwing’s motor. But that’s where the major similarities end.
“The big difference is the supercharger displacing 2.65 liters,” Allen tells us. “We had to increase that because we have higher inlet and exhaust restriction.”
The supercharger in the CT5-V comes in at just 1.7 liters. That’s a 64-percent increase in capacity, for those keeping track. Even though the engine bay is bigger in the Escalade, the need for acres of cooling apparatuses meant engineers had to get creative. The bigger blower means a final output of 682 hp and 653 lb-ft of torque, 14 more hp and 6 less lb-ft versus the CT5’s engine.
There’s more to it, of course. In place of the pneumatic actuator inside the supercharger feeding the engine in the CT5, there’s an electronic unit for the Escalade. That’s done to refine how boost comes on.
“Think of it like throttle body—you’ve got infinite positioning,” Allen says. “So you’re transitioning in and out of boost. It gives our calibrators a better chance of being able to refine those transitions. With the bigger supercharger you have a much larger volume of air we need to control. So that drove us using the electronic actuator.”
Those changes to the exhaust weren’t just for packaging. Engineers took into account the Escalade V’s use case as well. Remember, this engine is powering a three-ton building on wheels that needs to be able to tow. That means a lot of extra stress and heat being generated.
“This truck has cast stainless steel exhaust manifolds on it,” Allen explains. “The Blackwing has a tri-Y header.”
A tri-Y header, as the name suggests, is a header that forms three “Ys” with its construction. It goes from four tubes to two, forming the first two Ys, then from those two pipes to one, forming the third pipe.
“So with the truck application, and especially with the towing, we wanted to make sure that the manifolds could withstand a little bit higher EGTs (exhaust gas temperatures) during the towing application,” Allen says. “So it’s cast stainless steel.”
All that heat will kill power, which means designers had to beef up the cooling system to handle the temps.
“The challenging thing was you have almost 700 horsepower and you have to cool that,” Allen told us. “And then you have a vehicle that tows 7000 pounds. We had to have a big radiator. We have a heat exchanger in there for the charge cooler cooling circuit. And then we actually added a third electric fan, because the charge cooler cooling circuit is separate from the engine. And you need the additional fans to keep that cool.”
Keyword: How Cadillac Had to Change the CT5-V Blackwing Engine to Work in the Escalade V