The 3.5 EcoBoost is a Duratec engine, just a GDI version of the 3.5 Duratec, so they
should use the same heads. Inside the head may be different, the DOHC cam setup for
The 3.7 Duratec (code name Cyclone) is the N/A motor for heavy or premium vehicles.
The stroke is the same as the DT 3.5, with a bigger bore. The 3.7 in the Mustang
though, is a DOHC version, with Ti-VCT. The Mustang is the first American vehicle to
have a 3.7 Duratec motor since the '09 rear whel drive Lincoln LS. Was also the first
production engine to deliver in excess of 300 hp, with a ~31MPG rating.
The major problem, is they turned a $200 @ a shop parts & labor job to $1200+ to replace
the water pump. They buried it inside the motor, and run it off the timing chain. A
dealer wants over $2000 to replace it. They last up to 80,000 miles before the first