Chrysler Exposes Major Revisions to Pentastar V-6
To hear Chrysler tell it, the automaker’s Trio.6-liter Pentastar V-6 essentially will be a fresh engine when it makes its debut in the two thousand sixteen Jeep Grand Cherokee, its very first application in the FCA lineup.
Basic dimensional elements—bore, stroke, bore-center spacing—carry over, but the engineering team claims greater efficiency, improved torque characteristics, a petite horsepower uptick, and better NVH spectacle.
Fresh components include cylinder goes with an 11.Three:1 compression ratio (up from Ten.Two:1), eight-hole ignition coils, platinum-tipped spark corks, fresh valve springs, low-tension piston rings, lightened crankshaft and crank pins, extensive friction reduction, and cooling of exhaust-gas recirculation.
However, the fattest single efficiency improvement, according to FCA engineers, is a revision to the engine’s variable valve timing, providing intake-side valves a two-stage lift strategy—low lift for routine power requests, high lift when the driver calls for more urgency.
Operating range of the variable-valve-timing system has been enhanced from fifty to seventy degrees to mitigate detonation during hot starts, improving operation of the automatic engine stop-start (ESS) function. Carried forward from the current V-6, the ESS system has been enhanced with a fresh high-speed starter motor in order to reduce cranking time and produce quicker, smoother starts.
Conspicuous by its absence from the engine’s catalog of revisions is direct fuel injection. FCA chose to proceed with an upgraded port-injection system, citing added cost and weight as tradeoffs that go with direct injection. (According to FCA, the fresh engine will weigh three hundred twenty six pounds in the Grand Cherokee, four pounds less than the current V-6.) The engineers also looked at, and ultimately passed on, Fiat’s MultiAir induction system, for reasons of cost and U.S. market suitability. While it would be nice to see DI (or even MultiAir), this strategy gives FCA something in its pocket for future development of the engine.
Albeit FCA isn’t ready to produce all the engine’s spectacle specifics, it did expose that output in the Grand Cherokee advances from two hundred ninety to two hundred ninety five horsepower. Torque is said to improve by “more than 14.9 percent” inbetween one thousand and three thousand rpm. (Which would be . . . what? 14.91? 14.98? You’re getting ridiculously specific here, Chrysler.) Note that there was no mention of the maximum torque figure changing—it stood at two hundred sixty lb-ft in 2015—but the low-range boost will be welcome given that torque peaked at a rather lofty four thousand eight hundred rpm. FCA also anticipates a fuel-economy improvement of “more than six percent.” (So, 6.1?) That would translate to harshly eighteen mpg city and just over twenty five mpg highway.
The revised Three.6-liter V-6 will be under the rubber hood of the six-cylinder two thousand sixteen Grand Cherokee when it rolls into showrooms this fall. FCA is still mum on when it will spread to the rest of the lineup, but the Three.6-liter Pentastar presently emerges in the Dodge Challenger, Charger, Grand Caravan, Journey, and Durango; the Chrysler 200, 300, and Town & Country; the Jeep Wrangler; and the Ram ProMaster, Ram Cargo Van, and Ram one thousand five hundred pickup.