The History of the Harley-Davidson Twin Cam 96
Harley-Davidson’s Twin Cam 96 was first introduced in 2007 as an upgrade to the Twin Cam 88 which was an innovative replacement for the Evolution Engine (1984-1999). The beloved Harley-Davidson Evolution featured aluminum heads and cylinders and was an improvement over the Shovelhead engine.
Twin Cam 88 Engine (1999-2006)
In 1999, Harley-Davidson motorcycles introduced the Twin Cam 88 engine which produced 68 horsepower and 85 lb-ft of torque. This revolutionary engine for Harley-Davidson had two camshafts located in the engine block rather than the Evolution’s single camshaft located in the cylinder head for improved engine performance by allowing for better control over valve timing. Most 88s were carburated but by 2001, select Harley-Davidson models were manufactured with fuel injection. By 2007, with the introduction of the new TC96, all models had fuel injection.
Twin Cam 96 Engine (2007-2017)
Harley-Davidson motorcycles introduced the Twin Cam 96 engine in 2007 as an upgrade to the Twin Cam 88 and had about the same horsepower (68 HP) but better torque (92 lb.ft). It was designed to meet new emissions standards and provide better performance by using an electronic throttle control system, a new oil cooler, and an improved charging system. The TC 96 has 12-millimeter dual-coil plugs and offers better fuel efficiency than its predecessor traveling 54 miles a gallon on the highway. This new Harley-Davidson touring engine had a higher compression ratio of 9.2:1 compared to the Twin Cam 88's ratio of 8.9:1 and also had a new camshaft design improving low-end torque and throttle response.
Harley-Davidson touring bikes continued to use the Twin Cam 96 engine until 2017 when it was replaced by the more powerful Milwaukee-Eight engine which boasted 107 cubic inches producing 92 horsepower and 111 lb-ft of torque and later 114 cubic inches sending 100 horsepower and 119 lb-ft of torque to the rear wheel. This is an increase of 20% in power and 10% in torque over the Twin Cam 96.
The Two Twin Cam 96s Compared
The Twin Cam 96
Harley-Davidson made two different versions of its TC-96. The original was known for its vibration because it used a single-pin crankshaft with both connecting rods riding together on that pin. The weight of the pistons, rings, and connecting rods which change direction two times in one revolution create a lot of shaking at idle. This vibration smoothed out when revving up to higher speeds, but rubber mounts were needed to attach it to the frame.
This engine was created for the Harley-Davidson Touring and Dyna motorcycles which still vibrated pretty hard through the seat, floorboards, handlebars, and footpegs, but not as bad as the Harley-Davidson Evo. The Softail models, however, have a different version of the Twin Cam 96 which is much more balanced and feels completely different.
Twin Cam 96B
The “B” in the TC 96B stands for “balanced” because in select Harley-Davidson models including the Softail, the engine was completely counterbalanced. The drive chain passed under the crankshaft gear then went to the back of the counterbalance and again back to the front counterbalance weight before returning to the crankshaft.
Because of this setup, the counterbalancer weights rotate in their bearings in the opposite direction of the crankshaft’s rotation and at the exact same speed. Harley-Davidson engineers also used two smaller weights closer and equidistant to the crankshaft to eliminate any secondary vibration that might come from the single weight that’s mounted further from the crankshaft.
Unlike the Touring and Dyna motorcycles, the Softail’s Twin Cam 96B purrs at idle and is bolted directly to the frame since the vibration is all but eliminated. For those who are commuting, this engine works well in stop-and-go traffic.
The Power of the Harley-Davidson Twin Cam 96
The Twin Cam 96 displaces 96 cubic inches as its name suggests. This is up from the 88 cubic inches of the old Twin Cam 88. That comes out to 1584 ccs for the TC 96 as opposed to the TC88’s 1450 cc which is a 134 cc increase. It accomplishes this by increasing the length of the stroke by .38 inches from 4 inches to 4.38 inches while maintaining the same bore as the TC 88 at 3.75 inches.
Increasing the bore size, cubic centimeter engine displacement, and piston stroke can increase the horsepower and torque of an engine by allowing more air and fuel to enter the combustion chamber and burn more efficiently. The increase in engine displacement and diameter of the cylinders in turn increases the volume of air and fuel that can be compressed and ignited during the combustion process. This increase in volume allows the engine to burn more fuel and air in each cycle resulting in more power output.
Increasing the length of the piston stroke means that the piston travels farther up and down within the cylinder, and even if this is a slight increase, this still allows more air and fuel to enter the combustion chamber which creates more torque and overall power.
Improving the engine’s stroke increases the midrange horsepower and torque. The Twin Cam 96 has a horsepower of about 68 and generates 92.6 lb-ft of torque at 3500 RPMs. The Twin Cam 96B produces a little more torque at 94 lb-ft. Harley-Davidson advertises its bikes with an emphasis on torque instead of horsepower because its staple is cruisers not sport bikes and low-end torque is more important to its base. So the top speed is a modest 110-120 MPH depending on the model, aerodynamics, and aftermarket exhaust and upgrades.
The Twin Cam 96 is more powerful than the TC 88 not only because of its size but also because the starter is now attached directly to the inside primary housing unit which eliminates the need for the jackshaft, the internal oil passages connect the engine and transmission directly eliminating the need for external oil lines from the oil pump, and the new pistons and connecting rods are lighter for improved engine performance.
The Cruise Drive six-speed transmission is an improvement over the 88’s five-speed and is created with better and more accurate gear ratios intended to improve performance in every gear. This not only improves performance but also horsepower and torque.