By Christopher A. Sawyer
The Virtual Driver

(August 17, 2013) GM will debut its new three-cylinder engine at next month’s Frankfurt Motor Show debuting in the Opel Adam (pictured above). The turbocharged direct-injected triple is a direct competitor to Ford’s similarly sized three-cylinder turbo motor that will make its U.S. debut in the 2014 Fiesta.

The littlest EcoTec produces 113 hp and 122 lb-ft from 1,800 to 4,700 rpm, will be mated to a new six-speed manual gearbox that weighs just 82 pounds dry.

Engineers designed the die-cast aluminum block to reduce both radiated and structure-borne noise. The high-pressure fuel rail is isolated from the cylinder head, and the fuel pump and fuel lines are acoustically treated to further reduce noise. But where Ford uses an unbalanced flywheel and pulley to dampen its triple’s vibrations, GM uses a more conventional oil sump-mounted balance shaft to do the same. This is similar to how BMW tames the vibrations of the three-cylinder used in its new i8.

Other technologies used to reduce noise, vibration and harshness include:

    Acoustically-optimized covers for the engine’s top and front, the intake manifold and camshaft housings.
    Isolating the crankshaft with iron main bearing inserts.
    Inverting the camshaft drive chain teeth.
    Sourcing a low-hiss turbo compressor.
    Using a steel oil pan to dampen bottom end noise.

The 1.0-liter motor produces the same horsepower and more torque than GM’s current naturally aspirated 1.6-liter four. By integrating the exhaust manifold into the aluminum cylinder head and directly bolting the water-cooled turbo to it, the engine reaches its 122 lb-ft torque peak at 1,800 rpm, and holds it to 4,700 rpm. GM’s naturally aspirated 1.6-liter motor, on the other hand, produces 30% less torque at 1,800 rpm.

The new engine is mated to an equally new six-speed manual gearbox. The transmission is approximately 30% lighter than the unit it replaces, and extremely compact. It measures 14.7 inches along its axis, and can be used with engines rated at up to 162 lb-ft of torque. To help improve both shift feel and refinement, the new unit features wide, asymmetrically-cut dog teeth; triple-cone synchronizers on first and second gears; double-cone synchros on third and fourth; and a synchronized reverse gear. The engine will be built at GM’s new Szentgotthard plant in Hungary.

The Virtual Driver