Harley-Davidson Twin Cam engine
Differences from predecessor (Evolution engine)

Harley-Davidson Twin Cam engine

Section Title: Differences from predecessor (Evolution engine)
Table Section Text: None

Change	Evo	Twin Cam

Displacement	82 cu in (1,340 cc)	88 cu in (1,450 cc), 96 cu in (1,584 cc), 103 cu in (1,690 cc), 110 cu. in. (1,801 cc).

Oil pump	External. Connected through a series of gears.	Internal twin-gerotor. Connected directly to the right side pinion shaft.

Cams	Single, with 4 lobes.	One per cylinder, each with 2 lobes. This allows the push rods to be better aligned with the rocker arms.

Cam drive	Gears	Silent chain. This change was reported as necessary to meet EPA noise requirements.

Transmission attachment	Displaced from motor	Transmission casing is attached directly to the engine.

Oil tank	Usually surrounds battery box under the seat.	Below and behind the transmission assembly (except Softails, which are same as noted for the Evo)

Combustion chamber	"D" shape	"Bathtub" shape. Allows more efficient combustion and has higher compression.

Spark firing	Wasted spark (both plugs fire at the same time). The ignition system uses single coil.	No wasted spark. The ignition system employs dual coils. Plugs are 12 mm (0.47 in).

Cooling	Air-cooled	Also air-cooled. Increased cooling fin areas and an oil jet that sprays the bottom of the pistons provide additional cooling capability.

Sentence(s)

Harley-Davidson Twin Cam engine's displacement is 88 cu in (1,450 cc).

final_sentence: Harley-Davidson Twin Cam engine's displacement is 88 cu in (1,450 cc).