The Caterpillar D-343 is a large industrial grade diesel engine designed for marine applications, although it can also be found in applications such as diesel-powered power generators. Available in both a turbocharged and an aftercooled turbocharged edition, it combines fuel efficiency with a great deal of power, horsepower and torque.
The Caterpillar D-343 is a six-cylinder engine that operates on a standard four-stroke cycle. It has a 137-mm cylinder bore and 165-mm piston stroke and displaces 14.6 L. Its low idle speed is just 550rpm, and its redline occurs at 2,000rpm. Excluding protrusions, it is 32 inches across, 76.3 inches long and 49.7 inches tall.
The base, turbocharged, variant of the engine generated 238 brake horsepower at its shaft and 245bhp at its flywheel when running at 1,800rpm, consuming 13.8 gallons of fuel per hour. At 2,000rpm, it could generate 315bhp intermittently with an absolute maximum of 395bhp, both measured from the flywheel. The engine weighs 2216kg. when completely dry.
Caterpillar also offered an aftercooled variant: the D-343TA. This engine is more powerful, generating 359 and 370bhp at its shaft and flywheel at 1,800rpm, with intermittent and maximum power ratings of 460 and 550bhp. In exchange for its additional power, it consums more fuel, with a flow rate of 19.3 gallons per hour. It weighs 22.7kg. heavier.
The 501kg. MG514 marine gear transmission was Caterpillar's recommended mate for the D-343. It is a five-speed transmission capable of running in both forward and reverse with gear ratios from two-to-one up to six-to-one.