Adding Horses Page 2
Part 2: Cooler pistons create less carbon on the rings, so the engine runs cooler and lasts longer.
By Capt. Patrick Sciacca — June 2002
With more air in the cylinders, it was time to increase fuel to get the required horsepower. At one time this would have required adding new injectors and a new injection pump, but in the electronic 3196 it was accomplished via software changes, which required considerable research and development. Caterpillar updated the engine's processor from the ADEM II to the faster ADEM III, which it says better optimizes the control map by which the amount of fuel entering the combustion chamber is adjusted even more precisely to accommodate the changes in load and environment. But the processor change would work only if the "hardware" could accept it. "Fortunately on [the 3196] the fuel system could handle the higher horsepower," Tow says.
At the same time that the fuel and air systems were being increased, engineers were working to ensure that key engine components could tolerate the higher loads that come with increased horsepower. "We have design limits for all our engines' various components," says Tow. "After we make a horsepower increase, we check all components' temperatures and loads, to make sure that none are violated." For the C-12, Caterpillar focused on maintaining proper piston temperatures by changing the piston rings to increase heat transfer to the cylinder walls, and thereby to the coolant. They also adjusted the oil-cooling jets to spray oil more accurately to the underside of each piston, taking away heat more effectively. Cooler pistons create less carbon on the rings, so the engine runs cooler and lasts longer. One thing Caterpillar didn't do to the 3196 was increase its displacement (a function of bore and stroke) because the bore had already been taken as far as it could safely go.
This article originally appeared in the February 2003 issue of Power & Motoryacht magazine.