Ford SHO V8 Engine - 3.4 L

3.4 L

The 3.4 L SHO V8 was introduced in the spring of 1996. It incorporated many of the traits of the SHO V6, including the aluminum cylinder heads and 4-valve per cylinder DOHC design, but differed with an aluminum rather than iron block and no variable length intake manifold. A chain is also used to time the camshafts to crankshaft instead of the belts that the SHO V6s used. The SHO V8 has a split port style intake valve setup. The primary valve is exposed all the time and has the fuel injector spraying on it, while the secondary valve is only exposed when the Intake Runner Manifold Control opens the secondary plates at 3400 rpm. These secondary valves are called "secondaries" by SHO enthusiasts. Power was similar too, at 235 hp (175 kW) and 230 lb·ft (312 N·m) of torque.

Bore and stroke were identical to the Duratec 25 at 82.4 mm and 79.5 mm, respectively. The engines shared other traits as well, and insiders report that the designs are related, though not closely. Notably, the two engines share the same bell housing pattern and 60° V angle. The 60° angle makes it compact and more suitable for transverse mounting, but it is not ideally balanced—V8s are typically 90°—necessitating the use of a counter-rotating balance shaft.

Manufacturing was also a shared process. Ford manufactured the aluminum engine blocks, using a patented Cosworth process, at their Windsor, Ontario plant, then shipped them to Japan for finishing by Yamaha. The finished engines were shipped back to the Taurus plant in Atlanta, Georgia for installation.

Unlike the SHO V6, the SHO V8's valvetrain was an "interference" design, one that is shared by many engines built today, meaning that the piston will collide with the valves if the camshaft or timing chain fails. Due to some cam sprocket failures, the engine acquired a reputation for potentially catastrophic failure.