GMC was the first pickup to offer a V6 engine, and now the company is announcing that the new 4.3-liter V6 EcoTec3 available in the 2014 GMC Sierra pickup will be rated at 305 lb-ft of peak torque. GMC says that’s the highest of any standard V6 in the current full-size truck segment.
The new EcoTec3 features direct injection and continuously variable valve timing, plus cylinder deactivation for improved fuel economy. It will be rated at 285 horsepower. A regular-cab, shortbed 4×4 Sierra with the V6 will carry a tow rating of 7,200 pounds, which GMC says is up to 700 pounds more than the competition in a similarly equipped truck.
In making the announcement, GMC reflected on its V6 heritage, noting that it introduced a family of V6 engines in 1960, starting the 305ci model that was based on a 60-degree V block. Back then it was rated at 120 horsepower with 220 lb-ft of torque. Remember, that was flywheel horsepower. Today’s horsepower ratings take into account a number of factors like mufflers and accessories.
Shown is the original 305ci GMC V6 engine and an old advertisement promoting its cooling system.
“I’ve heard of some owners going more than 450,000 miles on the original engine,” says GMC truck historian Donald Meyer.
For its big trucks, GMC developed a 702ci “Twin Six” engine that appeared to be two 305s welded together as it used four exhaust manifolds and two intake manifolds. In fact, the engine was a single, dedicated casting but shared a number of parts from the 305. That engine was rated at 250 horsepower and a diesel-like 585 lb-ft torque.

For the 1960 model year, GMC was the first brand to introduce a V-6 engines in pickup trucks. There was also a V-12 based on the same engineering for commercial-grade heavy-duty trucks.