How one engine manufacturer upgraded a powerplant’s performance.
By Capt. Patrick Sciacca — June 2002
I have friends who love to match their cars in quarter-mile races (legally, of course), and to squeeze every bit of horsepower out of their engines, they even add nitrous oxide. While the result is a neck-snapping, lift-off-like jolt, this temporary enhancement is just not a practice conducive to long engine life.
Boat owners are not likely to compete in quarter-mile increments hoping to beat 12 seconds, but like their automobile-enthusiast counterparts, many of them do want to get more horsepower out of their powerplants. Fortunately, most prefer to leave that job to professionals: the people who manufacture marine diesels. But how does an engine manufacturer take an existing engine and increase its output without making major changes like increasing the displacement and still manage to maintain engine durability? Caterpillar recently completed an 18-month enhancement project to its 660-hp 3196, creating the 700-hp C-12, and it agreed to explain to me just how it added horses.
There are many ways to increase horsepower in an engine. Which method engineers select is at least partly dependant upon the size of the increase they're looking for. In this project, the increase was considered modest, according to Tryg Tow, project engineer for the Marine Product Engineering Power Systems Marketing Division of Caterpillar. So to achieve the 40-hp boost, Caterpillar started by addressing the 3196's air intake system.
The first step was a new turbocharger that would pump more air into the cylinders. Tow says that Caterpillar polled its suppliers and discovered a higher efficiency turbocharger that fit perfectly. "We leveraged off that," he says, by lowering exhaust manifold restriction.
This article originally appeared in the February 2003 issue of Power & Motoryacht magazine.